Tag: agriculture

Toddlers’ diarrhea is a well-known and benign condition that often responds by simply removing excess juice from the diet of 1- to 4-yearolds. However, malabsorption of carbohydrate in juice, especially when consumed in excessive amounts, can result in chronic diarrhea, flatulence, bloating, and abdominal pain.‍Fructose and sorbitol have been implicated most commonly,but the ratios of specific carbohydrates may also be important.‍ The malabsorption of carbohydrate that can result from large intakes of juice is the basis for some health care providers to recommend juice for the treatment of constipation, particularly in infants. The North American Society of Pediatric Gastroenterology, Hepatology, and Nutrition constipation guideline suggests taking advantage of the sorbitol and other carbohydrates contained in some juices, such as prune, pear, and apple juices, to help increase the frequency and water content of stools for infants with constipation.A basic premise of the Dietary Guidelines for Americans, the most recent version of which was published in 2015, is to focus on nutrient-dense foods.Fruit is 1 of the key focus foods in the dietary guidelines.Fruit, along with vegetables, is recommended to provide necessary vitamins and minerals, reduce the risk of cardiovascular disease, potentially protect against cancer, and curb excessive caloric intake. For example, children consuming approximately 1000 kcal/day should have ∼1 cup of fruit per day, whereas those consuming approximately 2000 kcal/day should consume ∼2 cups of fruit per day. Although whole fruit is to be encouraged,plastic pot up to half of the servings can be provided in the form of 100% fruit juice . A 6-ounce glass of fruit juice equals 1 fruit serving. Fruit juice offers no nutritional advantage over whole fruit. A disadvantage of fruit juice is that it lacks the fiber of whole fruit. Kilocalorie for kilocalorie, fruit juice can be consumed more quickly than whole fruit.

Reliance on fruit juice instead of whole fruit to provide the recommended daily intake of fruit does not promote eating behaviors associated with the consumption of whole fruit. Because recent studies suggest that pure orange juice consumption has health benefits in adults, further research is needed to determine whether children and adolescents may derive similar benefits.‍Pediatricians play a central role in children’s health and nutrition by providing guidance to pediatric patients and their parents. Pediatricians can also advocate for changes in public policy, especially in schools, where improved fruit and vegetable intake has been associated with policies promoting healthier dietary choices.‍Open assessment and recommendations for appropriate dietary habits, including consuming whole fruit rather than fruit juice, can help encourage parental support of healthy rates of weight gain.Although other risk factors associated with obesity may be important to consider, a recent study suggests that special attention may be indicated for infants and children of women who are overweight before bearing children.‍Parents need to be informed that unpasteurized juice products may contain pathogens, such as Escherichia coli, Salmonella species, and Cryptosporidium species, which may be harmful to children. These organisms are associated with serious diseases, such as hemolyticuremic syndrome.‍If parents choose to give their children unpasteurized juice products, they should do so with caution and be advised that this is an unsafe practice. Commercially prepared unpasteurized juice must contain a warning on the label that the product may contain harmful bacteria.‍This guidance does not apply to certain modes of sale , but families should remain vigilant when providing unpasteurized juice products to children. Pasteurized fruit juices are free of microorganisms and are safe for infants, children, and adolescents.The American Academy of Pediatrics recommends that human milk be the only nutrient fed to infants until approximately 6 months of age.‍

For mothers who cannot breastfeed or who choose not to breastfeed, a prepared infant formula can be used as a complete source of nutrition. No additional nutrients are needed. There is no nutritional indication to give fruit juice to infants younger than 6 months. Offering juice before solid foods are introduced into the diet could risk having juice replace human milk or infant formula in the diet, which can result in reduced intakes of protein, fat, vitamins, and minerals such as iron, calcium, and zinc.‍Malnutrition and short stature in children have been associated with excessive consumption of juice.‍It is optimal to completely avoid the use of juice in infants before 1 year of age. When juice is medically indicated for an infant older than 6 months, it is prudent to give the juice to the infant in a cup. Dental caries have also been associated with juice consumption.Prolonged exposure of the teeth to the sugars in juice is a major contributing factor to dental caries. Recommendations from the AAP and American Academy of Pediatric Dentistry state that juice should be offered to toddlers in a cup, not a bottle, and that infants not be put to bed with a bottle in their mouth.‍The practice of allowing children to carry a bottle, easily transportable covered cup, open cup, or box of juice around throughout the day leads to excessive exposure of the teeth to carbohydrate, which promotes the development of dental caries.‍ Infants can be encouraged to consume whole fruit that is mashed or pureed. After 1 year of age, fruit juice may be used as part of a meal or snack. It should not be sipped throughout the day or used as a means to calm an upset child. Because infants consume <1600 kcal/day, 4 ounces of juice per day, representing half of the recommended daily serving of fruit, is more than adequate. The AAP practice parameter on the management of acute gastroenteritis in young children recommended that only oral electrolyte solutions be used to rehydrate infants and young children and that a normal diet be continued throughout an episode of gastroenteritis.

Surveys show that many health care providers do not follow the recommended procedures for the management of diarrhea.‍The high carbohydrate content of juice , compared with oral electrolyte solutions , may exceed the intestine’s ability to absorb carbohydrate, resulting in carbohydrate malabsorption. Carbohydrate malabsorption causes osmotic diarrhea, increasing the severity of the diarrhea already present.‍Fruit juice is low in electrolytes. The sodium concentration is 1 to 3 mEq/L. The stool sodium concentration in children with acute diarrhea is 20 to 40 mEq/L. Oral electrolyte solutions contain 40 to 45 mEq sodium/L. As a replacement for fluid losses, juice may predispose infants to development of hyponatremia. Concern has been raised that infants exposed to orange juice had an increased likelihood of developing an allergy to it. The development of a perioral rash in some infants after being fed freshly squeezed citrus juice is most likely attributable to the chemical irritant effects of acid.‍ 53 Diarrhea and other gastrointestinal symptoms observed in some infants were most likely attributable to carbohydrate malabsorption. Although allergies to fruit may develop early in life, they are uncommon.‍Most issues relevant to juice intake for infants are also relevant for toddlers and young children. Fruit juice and fruit drinks are easily over consumed by toddlers and young children because they taste good. In addition, they are conveniently packaged or can be placed in a bottle or transportable covered cup and carried around during the day.Because juice is viewed as nutritious,grow bag limits on consumption are not usually set by parents. Toddlers and young children can be encouraged to consume whole fruit instead of juice. Like soda, it can contribute to energy imbalance. Pediatricians should support policies that seek to reduce the consumption of fruit juice and promote the consumption of whole fruit by toddlers and young children already exposed to juices. This support should include policies of the Special Supplemental Nutrition Program for Women, Infants, and Children , provided that those policies do not have negative nutritional consequences for children without access to fresh fruit. In addition, high intakes of juice can contribute to diarrhea, over nutrition or under nutrition, and the development of dental caries. The dilution of juice with water does not necessarily decrease the dental health risks.Juice consumption presents fewer nutritional issues for older children and adolescents, because they consume less of these beverages. Nevertheless, juice intake should be limited to 8 ounces/day, half of the recommended daily fruit servings. It is important to encourage the consumption of the whole fruit for the benefit of fiber intake and a longer time to consume the same kilo calories. Excessive juice consumption and the resultant increase in energy intake may contribute to the development of obesity. One study found a link between juice intake in excess of 12 ounces/day and obesity.‍

Other studies, however, found that children who consumed greater amounts of juice were taller and a had lower BMI than those who consumed less juice‍ or found no relationship between juice intake and growth variables.A more recent study suggested that varying intakes of 100% juice were not associated with obesity.‍More research is required to better define this relationship.Global production of pollinator dependent crops has increased by 300% in the past 50 years . At the same time, managed honey bee populations are declining due to a complex of factors including novel diseases, pesticides and habitat change . Pollinator deficiencies may precipitate significant yield reductions and increased food prices, ultimately jeopardizing food security . Unmanaged bees are highly effective pollinators of a variety of crops and act as insurance against loss of pollination function due to honey bee deficits . While proximity to natural habitat increases populations of such alternate pollinators , intensive agricultural landscapes often contain little remnant habitat. As a result, re-diversification of agricultural areas has been proposed as a means of bolstering pollination services from these alternate pollinators . Diversification of agricultural landscapes can take place at many scales, including within fields , along field edges , or bordering landscape features . One benefit of field edge techniques is that they create habitat without sacrificing arable land , and comprise a large portion of non-cropped area in farming regions globally . Farm bill conservation programs in the United States and agri-environmental schemes in the European Union prioritize on-farm habitat creation projects that target pollinators, providing incentives through cost-share programs . Despite the prominence of these programs, there is little information as to the effectiveness of field-margin diversification techniques, and specifically, whether they can bolster pollinator services and affect yields to the same levels documented in patches of natural habitats while simultaneously conserving pollinator species . One common field edge diversification technique, hedgerow restoration , has been found to increase pollinator richness within field edges and up to 100 m into nearby crop fields . Additionally, hedgerows show potential for increasing pollination function within adjacent fields. Using sentinel canola plants, Morandin, Long and Kremen found that wild bees enhanced seed set, once the contribution from managed honey bees was accounted for. However, the canola plants provided a highly attractive resource within an unattractive crop matrix of processing tomato, which provides few nectar rewards and requires buzz-pollination to release pollen stores. These conditions are not reflective of the field conditions created by monoculture plantings of pollinator-dependent crops, which generate hundreds of thousands of synchronous, though short-lived, blooms within a single field . Pulses of highly attractive floral resources can create dilution effects, drawing species away from adjacent seminatural habitat and reducing pollination services there . Yet in spite of the attractiveness of MFC fields, wild bee abundance and richness has been found to be higher in habitats, including hedgerows, in closer proximity to MFC fields . The effects of MFCs may be species-specific, with some exhibiting higher preference for MFCs over other resources . Specialist pollinators, such as the squash bee , seek out fields of their host plant, cultivated squash, in the landscape . While the influence of MFCs on pollinator populations and services has been well-studied, whether the presence of field-scale restorations can augment pollinator populations and pollination services within MFC fields remains an open question . We examine the ability of hedgerows to enhance pollination services in a simplified agricultural landscape when adjacent to a mass-flowering, pollinator-dependent crop, cultivated sunflower . We ask whether the identity of the pollinator species found within hedgerows during the crop bloom period is the same as those found within adjacent sunflower fields. Then, using an independent data set, we determine whether the most abundant wild sunflower visitors, sunflower specialist bees, also utilize hedgerow plantings in our study landscape.

Native to East Asia, Drosophila suzukiihas been a major invasive pest of soft-and thin-skinned fruits since it was first detected in 2008 in North America and Europe and has been found recently in South America. Drosophila suzukii is highly polyphagous, being able to oviposit and/or reproduce in various cultivated and wild fruits. Its fast development and high reproductive potential can lead to explosive population increases and significant economic losses to crops. Though various management strategies, including behavioral, biological, chemical and cultural approaches, have been implemented to suppress D. suzukii populations and reduce crop damage, current control programs rely heavily on insecticides that target adult flies in commercial crops. Because non-crop habitats can act as a reservoir for the fly’s reinvasion into treated crops, area-wide Integrated Pest Management strategies that reduce population densities at the landscape level need to be developed for such a highly mobile and polyphagous pest. To develop area-wide programs, it is critical to understand how D. suzukii populations persist and disperse in the landscape as the season progresses. Many environmental factors, such as local climatic and landscape traits, may trigger the dispersal of D. suzukii populations to escape resource-poor habitats or unfavorable weather conditions. Landscape composition surrounding cultivated crops, such as forests and shrub vegetation, could act as sinks, sources,black flower bucket shelters or overwinter sites for the fly populations. For this reason, the availability of alternative hosts could play an important role in sustaining fly populations and dictating their local movement patterns when favorable hosts are not available. Researchers have provided a better understanding of local D. suzukii population dynamics. Still, there are gaps that limit our understanding of the relative importance of different hosts for D. suzukii within some geographical regions.

For example, the seasonal periods of host utilization and the importance of non-crop hosts within the agricultural landscape need to be understood to develop area-wide programs. In this framework, this study aimed to illustrate the temporal dynamics of host use by D. suzukii in California’s San Joaquin Valley, one of the world’s major fruit growing regions. Drosophila suzukii was first detected in California when it was found infesting strawberries and cranberries in Santa Cruz County in 2008. Since then, damaging populations have been recorded from cherries, cranberries, mulberries, raspberries and strawberries, mainly in the coastal or northern California fruit growing regions with relatively mild summer. In comparison, California’s interior San Joaquin Valley has hotter summers and colder winters, and while D. suzukii is collected in cherry, citrus, fig, grape, kiwi, mulberry, nectarine, peach, persimmon, plum and pomegranate as well as in non-crop habitats surrounding the orchards, reported crop damage has been mainly on cherries. Adult fly captures show two main periods of activity—spring and fall—and low captures in winter and summer. The number of captured flies was positively related between pairs of sampled sites based on their proximity, but it was negatively related to differences in fruit ripening periods among crops, suggesting that fly populations might move among crop and/or non-crop habitats during the year. Though adult flies are captured in various orchard crops, it is not clear whether these fruits are vulnerable and serve as hosts. For example, the potential impact of D. suzukii on wine grapes in Italy was discussed by Ioriatti et al., who observed D. suzukii oviposition in soft-skinned berries, and, in Japan, some grape cultivars were reported as hosts for D. suzukii. In Oregon, Lee et al. found that D. suzukii was able to successfully oviposit in some wine grape cultivars but that offspring survival was low , whereas other studies observed no or low levels of infestation of intact grapes in the field or laboratory.

Some of the initial work in Japan reported that D. suzukii emerged only from fallen and damaged apple, apricot, loquat, peach, pear, persimmon and plum, but Sasaki and Sato reported that healthy peach fruit can be infested. However, in California, Stewart et al.reported that intact peach fruit are unlikely hosts. No doubt, many fruits with hard or hairy skin can be colonized if wounds are available to allow flies to oviposit in the pulp. In this study, we document the temporal patterns of host use by D. suzukii in California’s San Joaquin valley by sampling intact and damaged fruits of various crop and no-crop plants throughout the fruiting season. We evaluated the suitability of key fruits, including several unreported ornamental and wild host fruits as hosts for the fly, particularly focusing on the host status of grapes—considered to be a non-preferred host—and cherry—considered to be a preferred host. Wine grapes can contain uniquely high levels of organic acids that are important for producing wines less susceptible to microbial and oxidative damage and with more vibrant color. The levels of acidity decrease as fruit are ripening, but they remain high throughout the ripening process. For this reason, we also examined the impact of tartaric acid concentrations on the fly’s fitness. For cherries, we examined the effects of cultivar and fruit size on the fly’s performance. We additionally monitored adult fly populations at different elevations—from the Valley floor east to the foothills and Sierra mountains—to determine if the fly is active at higher elevations during the hot summer when the fly populations were extremely low in the Valley’s agricultural areas. We discuss the implications of this information for area-wide management in the San Joaquin Valley. A total of 17 common fruits were sampled in a temporal sequence of fruit ripening, including twelve important crops , three ornamentals , and two wild host plants . Samples were taken from 2013 to 2015 at the University of California’s Kearney Agricultural Research and Extension Center, near Parlier, California and near Brentwood, California .

Ornamental fruits were also collected in riparian areas surrounding agricultural crops near Bentwood. Bitter cherry, Prunus emarginataEaton , and the Cascara buckthorn, Frangula purshianaare endemic to western North America; these fruits were collected at higher elevations 1683 m near Shaver Lake, California . For all species, both intact fruit and damaged fruit were collected as available,square black flower bucket as the fruit were at a susceptible ripening stage for D. suzukii oviposition. A total of 30–50 fruit were collected when at a susceptible ripening stage for each species, although the number of intact ornamental and wild fruits varied depending on the availability.Collected fruits were placed individually or in groups of 10–50 in deli cups and held under controlled conditions at the University of California’s Kearney Agricultural Research and Extension Center . Deli cups were covered with fine organdy cloth and fitted with a raised metal grid on the bottom to suppress mold growth. A piece of tissue paper was placed underneath the fruit to absorb any liquid accumulation. Emerged flies were collected every 2–3 d, frozen, and then identified as either D. suzukii or other drosophilids. Only those flies that emerged within 2 weeks following field collection were counted to exclude the possibility of second-generation flies.All laboratory studies were conducted under controlled conditions, as described above . A laboratory colony of D. suzukii was established from field collections of infested cherries at Kearney. The fly larvae were maintained on a standard cornmeal-based artificial diet using methods described by Dalton et al., and adult flies were held in Bug Dorm2 cages supplied with a 10% honey–water solution and petri dishes containing standard cornmeal medium sprinkled with brewer’s yeast for feeding and oviposition. Field-collected D. suzukii were introduced into the colony yearly to maintain the vigor of the colony. All tests used 1–2-week-old adult female flies that had been housed with males since emergence . To determine if D. suzukii can oviposit within and develop from damaged or rotting navel oranges, a single adult female D. suzukii was exposed to a whole fresh fruit, halved fresh fruit, rotting whole fruit, or halved rotting fruit for 24 h in the acrylic cage. To simulate the natural decay process of a fallen orange, fresh oranges were placed individually on wet sandy soil in deli cups until the fruit started to rot. The halved fruit were allowed the same amount of time as the whole fruit but were cut into halves just prior to the test. On average, rotted fruit had 42.3 ± 7.3% of their surface covered by mold growth. Following exposure, the numbers of eggs laid were counted, and the fruit was then held in the cage until the emergence of adult flies.

Each treatment started with 25 replicates; however, a few replicates were discarded because of contamination by other drosophilids that likely occurred during the regular examination for the decay status of the fruit. A sub-sample of 10 fruit was measured to determine the Brix levels of fresh and rotting fruits. To determine the possible effect of tartaric acid on D. suzukii survival and development, seven different concentrations of tartaric acid were mixed with a standard artificial diet. The powdered tartaric acid was purchased from a wine and beer brewing store in Fresno, CA, USA, and mixed with the diet just before the diet solidified. The content of tartaric acid in grapes can vary depending on cultivar, ripeness, and environmental conditions; for example, Kliewer et al. reported a tartaric acid content ranging from 3.7 to 13.2 g/L in different cultivars and from 3.4 to 9.2 g/L in early- vs. late-harvested cultivars. The doses used here covered these reported ranges. Each treatment had 20–22 replicates, and each replicate started with 10 D. suzukii eggs from the laboratory culture that were placed in drosophila vials over the diet. The number of developed adults was recorded. A sub-sample of 25 pupae from each treatment was measured for pupal length and width , and the volume of each pupa was estimated based on the formula 2. Apple cider vinegar traps were used to monitor fly populations at four different elevations from the Valley’s low agricultural areas to the Sierra Nevada: Kearney , lower foothills , higher foothills and Sierra mountains . Traps at Kearney were placed in a mixed stone fruit orchard; traps at the three higher elevations were along Highway 168, with the foothill sites in residential yards with fruit trees and the Sierra site at the forest’s edge in bitter cherry bushes. Three traps were placed at each location, approximately 200 m apart. Collection methods were similar to Wang et al.. Briefly, traps were constructed of plastic containers filled with apple cider vinegar and a small amount of Bon-Ami Free and Clear® unscented soap to serve as a surfactant. Traps were hung on tree branches at head-height and then checked and replaced weekly from June to November 2017. Captured arthropods were placed into 95% ethanol in small glass bottle and later examined under a dissecting microscope to count the number of D. suzukii. Counts of emerged adult D. suzukii were based on total fruit samples. Laboratory data on fruit size preference, citrus test and grape acidity effect were presented as treatment means , and treatment effects were compared with the Analysis of Variance .For host suitability tests, since fruit varied in weight, the percentage of D. suzukii eggs that successfully developed to adults was calculated based on eggs per gram fruit to standardize the comparison among different treatments. The percentage of eggs that successfully developed to adults on different fruit species or different cherry cultivars were subject to further analysis of generalized linear model with binomial distribution and log-link function by considering the effect of both fruit species or cultivar and egg density per gram fruit, as well as the interactions of these two factors. To separate the means among different treatments, the percentage data were also arcsine transformed as needed to normalize the variance and analyzed using ANOVA. A separate analysis with 10 different cherry cultivars did not yield a significant effect of the Brix on the percentage of eggs that successfully developed to adults, although we could not rule out the possibility that Brix and other chemical properties may affect other fitness parameters of the developed flies. Many of the differences in chemical traits among different fruits could be attributed to geographic location and differences in environmental and cultivation conditions rather than inherent varietal properties, such as in cherries. In the current study, chemical differences were controlled to some extent, as cherry cultivars used were grown in the same plot with the same fertilization and irrigation regimes.

Currently, there are no integrated pest management plans available for control of citrus thrips in blueberry. This is primarily due to the recent nature of this crop-pest association. Avocado thrips, Scirtothrips perseae Nakahara, is a relatively new pest of avocados in California. It appeared in the state in 1996, and, at the time, was a species new to science . By 1998, crop damage reduced industry revenues by 12% . Avocado thrips adults can feed on over 11 plant species’, however, larvae have been found only on avocados in the field in both California and Mexico, suggesting that S. perseae has a highly restricted host range . Although it has little effect on tree health, avocado thrips feed directly on immature fruit , and obvious feeding scars cause severe downgrading and culling of damaged fruit . With a limited number of pesticides available for thrips control and the propensity with which economically important thrips develop insecticide resistance, it is wise to monitor population levels carefully, limit treatments to population levels of economic concern and time treatments optimally . Appropriate cultural practices and conservation of natural enemies should be practiced in concert with the use of pesticides only on an as-needed basis. Thus, continuing the search for effective biological and chemical controls useful in citrus and avocado thrips management is important. For both species of thrips, some pupation occurs on the tree in cracks and in crevices’, however, the majority of both species drop as late second instars from trees to pupate in the upper layer of the leaf litter under trees . Propupae and pupae are rarely seen, move only if disturbed, and do not feed. Thus, pupation in the upper layers of the soil surface may create the ideal interface for control using the entomopathogenic fungi Beauveria bassiana . Coarse organic mulch beneath trees and the maintenance of a mulch layer,plastic flower bucket a common practice by many growers as a method of Phytophthora spp. management in avocados , may reduce survival of thrips that drop from trees to pupate below the tree.

The effectiveness of mulching to control thrips is uncertain and labor costs are required to add mulch may not be justified solely for thrips control. There is increasing pressure in the U.S. to move away from broad-spectrum insecticides and focus on alternative methods of control, e.g., genetically modified crop plants expressing Bacillus thuringiensis toxins , use of entomopathogens, and similar approaches. Applications of B. bassiana have been reported to decrease populations of thrips in greenhouse cucumbers, chrysanthemums, gerbera daisies, roses, and carnations . Microbial insecticides containing δ-endotoxins from Bt have been used as alternatives to conventional chemical insecticides for almost 70 years . Bt produces insecticidal proteins during the sporulation phase as parasporal crystals. These crystals are primarily comprised of one or more proteins, i.e. Crystal and Cytolitic toxins, also called δ-endotoxins. From a practical perspective, Cry proteins are parasporal inclusion proteins from Bt that exhibit experimentally verifiable toxic effects to a target organism or have significant sequence similarity to a known Cry protein . Similarly, Cyt proteins are parasporal inclusion proteins from Bt that exhibit hemolytic activity or has obvious sequence similarity to a known Cyt protein. These toxins are highly specific to their target insect, are innocuous to humans, vertebrates and plants, are regarded as environmentally friendly, are completely biodegradable, and show little adverse effect on non-target species . The Cyt proteins are significantly different both in their structure and their biological activities from the Cryproteins. However, Cyt proteins have shown toxicity to non-dipterous insects . In fact, Cyt proteins in some cases can extend activity to other Bacillus spp. for mosquitoes that lack the proper receptor . Many studies with thrips involving Bt proteins have typically evaluated Cry toxins in transgenic crops targeted mainly toward lepidopterous pests and there are no published studies we know of representing the impact of Cyt proteins on thrips. Due to the synergism seen between these two Bt proteins and the method of thrips feeding, commonly described as ‘punch and suck’ , whereby leaf tissue is macerated prior to ingestion, we hypothesized that Cry or Cyt proteins could potentially be useful against thrips pests.

The goal of this investigation was to determine if Cry or Cyt proteins or B. bassiana could be used effectively to manage citrus and avocado thrips. Field management of both thrips species is the ultimate goal with these biopesticides but field studies are laborious and expensive. Thus, we evaluated these materials in the laboratory to determine which were sufficiently efficacious to warrant follow-up field studies. Leaves of both avocado and citrus for all bioassays were chosen in observably identical states; young and soft but fully expanded leaves were used as these are the type on which both species of thrips prefer to feed and large leaves were needed to fit in the Munger cell bioassay units that confined the thrips on treated leaves . Briefly, Munger cells were constructed by using a Plexiglas sandwich; the middle cell layer was drilled with 3.2-cm diameter bit to provide a circular test arena . The upper and lower parts of the Plexiglas sandwich were solid and between the lower base and test arena a piece a piece of filter paper was placed to allow moisture exchange and to extend the life of the leaf during the bioassay. Airflow through the test arena was provided through two holes drilled through the center cell layer directly opposite one another, with fine-mesh screening melted onto the interior of the test arena to prevent escape. The Plexiglas sandwich was held together with four binder clips positioned such that the airflow was not covered. Once dry, the leaves were placed on the filter paper in Munger cells and the respective thrips species was added. The lid was placed on the cell but leaving the cell arena exposed, so that once the thrips were added, the cells could be closed quickly. Female and late second-instar avocado thrips and citrus thrips were then placed on treated leaves of their respective host plants inside the Munger cell. Control leaves for both species were treated with a mixture of the same suspension ingredients minus the protein. Bioassays were conducted concurrently in the following manner for both species: adult female thrips were placed on leaves coated with activated or inactivated forms of both Cyt1A and Cry11A, immature thrips were also placed on leaves coated with activated or inactivated forms of both Cyt1A and Cry11A, and all combinations for adults and immature thrips were carried out along with the corresponding control cells.

The Munger cells were closed and placed in an environmental chamber at 28ºC, 55% RH, and long daylight conditions . The bioassay was replicated on two separate dates . A minimum of 10 individuals was placed into each Munger cell and thrips were checked daily for eight days to assess mortality. Post seven days,flower buckets wholesale the integrity of the leaves was questionable and in all but one bioassay, mortality was observed before seven days; thus data were analyzed using day 7 mortality. Mortality was determined by lack of movement after gently probing each thrips with a small brush. Six strains of B. bassiana were obtained from the USDA-ARS Western Integrated Cropping Systems Research Unit located in Shafter, CA. GHA is the commercially available strain found in the field formulation of B. bassiana, Mycotrol O and the greenhouse formulation BotaniGard ES, and each of the other five strains were obtained via isolation from soils in Kern County by USDA-ARS collaborators in 2000. They were stored at – 80ºC. Culture methods for the thrips experiments were similar to those described previously for Lygus hesperus Knight bioassays and were conducted by collaborators from USDA-ARS, Shafter, CA. Briefly, isolates were grown on SDAY media, or Sabouraud’s dextrose agar plus yeast extract . The conidia were harvested from culture plates after 10–14 days incubation by scraping with a sterile rubber policeman into a 0.01% solution of Silwet L- 77 . The conidia were then enumerated with a hemocytometer. For preservation and storage, glycerol was added to the conidial suspension and stored in aliquots of 2 × 108 in a 2 ml solution at −80°C until needed for bioassays. Conidial viability was assessed following incubation for 16 h in potato dextrose broth just prior to use in experiments. Viability was determined by adding a sample of approximately 107 conidia to 20 ml potato dextrose broth and incubating ca. 16 h in a rotary shaker at 28°C. Conidia germination was examined under a compound microscope at 400× and scored as viable if the germ tube was at least twice the length of the conidium. Percentage viability was measured on 250 conidia of each isolate. All bioassays were conducted on the basis of the number of viable conidia measured after thawing and the desired concentrations were formulated by serial dilution. The strain from Mycotrol was isolated and cultured exactly as above to eliminate possible effects of production methods and formulation ingredients on insecticidal activity. Glycerol was not removed prior to using the conidia in bioassays. All six B. bassiana strains were suspended in 0.01% Silwet in a de-ionized water solution and evaluated on the same date at four concentrations for each thrips species. The control consisted of 0.01% Silwet in de-ionized water solution. Each of the 25 treatments was evaluated using five Munger cells , which contained a minimum of ten adult female thrips. These bioassays were repeated on 10 dates with both species tested simultaneously on each date .

Groups of thrips were anesthetized by exposure to CO2 for 15-30 sec, and each strain was administered to the dorsum of the abdomen of each knocked out thrips quickly and carefully in a 1µl drop with a Burkard Hand Microapplicator over filter paper. The droplet spread the length of the thrips immediately and the thrips was then deposited, still knocked out, onto the leaf tissue in the Munger cell. Once a minimum of 10 treated thrips were added, Munger cells were closed and sealed with binder clips and placed in an environmental chamber at 28ºC, 55% RH, and long daylight conditions . Each cell was checked daily for seven days to observe infection by the fungus. Each cell was carefully removed daily and the filter paper doused with water to prevent leaf desiccation. Individuals infected with B. bassiana were defined as those whose natural activity was retarded and/or showed arrestment and subsequently produced mycelia, which was confirmed post bioassay. Mortality caused by mycosis was confirmed on the basis of visual observation and then crushing individuals to reveal the presence of mycelial growth. When mycelial growth was not apparent, crushed individual thrips were placed on potato-dextrose agar plates for 5 days and then re-examined for the presence of mycelial growth. Data were analyzed after Abbott’s correction for control mortality using log-probit analysis with PROC PROBIT on SAS 9.2 and using the Raymond Statistics package . The purpose of the probit analysis was strictly for gross strain comparison. Probit analysis was used to estimate the LC50 and LC95 levels, confidence intervals, and χ 2 values for each strains. Lethal concentrations with overlapping 95% confidence intervals were not considered significantly different. The daily check data were analyzed as non-cumulative counts per day via the Survival Distribution Function on SAS 9.2 , where observation time represented the probability that the experimental unit from the population would have a lifetime exceeding that time with the variables strain and concentration. Assessments for each variable by species were done with Log-rank and Wilcoxon tests and multiple comparisons for the log-rank test were adjusted by using Tukey-Kramer method. Data were then plotted as estimates of the survivor function for the different strains separately for each species. Bacillus thuringiensis israelensis produces two groups of toxic proteins, the Cry and Cyt toxins that have different modes of action.In this investigation, results with Cyt1A and Cry11A were disappointing as both activated and inactivated forms of both proteins showed little effect against adult and second instar citrus thrips and avocado thrips. To our knowledge, there have been no reports of Bt endotoxins with activity against Thysanoptera, although Cyt1Aa was found to be toxic to the non-target species Chrysomela scripta Fabricius .

Until such time, rigorous quality control using protein analysis methods such as qPCR or enzyme linked immunosorbent assay remains a sensitive method to confirm such contaminants are not detected in therapeutic diets fed for the purpose of the clinical diagnosis of CAFR. This remains the industry standard for quality control of commercially produced diets, including extensively hydrolyzed diets. In conclusion, this study confirms that commercial RMBD should not be considered appropriate for selection as ED in the diagnosis of CAFR as a result of their tendency to include unlisted protein ingredients, which can differ from batch to batch. A clinician should use caution when interpreting the results of an owner-directed ED trial using RMBD to exclude CAFR as a cause of their pet’s pruritic dermatopathy, and veterinarian-guided elimination diet oversight is still recommended. Until further evidence is presented, an elimination diet and provocation trial with a patient-appropriate prescription-based diet subjected to applicable quality control or a home-prepared novel protein diet remain the current diagnostic standard for CAFR.The CDPS is nationally recognized as the oldest, state-specific tracking survey for fruit and vegetable intake in the country. In 2005, it will represent sixteen years of bi-annual survey data using a modified 24-hour recall telephone interview methodology. Before this study, the examination of trends over time, especially for the race/ethnic groups of interest and for their low-income cohort, could not rule out seasonal effects. Because the CDPS has not always spanned the exact same months,plastic planters wholesale although generally it covers July through October, seasonal issues concerning the race/ethnic samples have been suspect.

The results of this study enhance both the interpretative dimensions of past and future CDPS findings. This study set out to achieve four objectives that are intended to illuminate and augment observations and methodological issues related to the California Dietary Practices Surveyin tracking fruit and vegetable consumption in the California population. The first and primary objective is to explore whether seasonal variation exists during the months of the year. The second is to quantify differences among, and seasonality effects as it relates to, the race/ethnic groups tracked by the CDPS, specifically Whites, Latinos, and African Americans. The third objective is to see if Latino acculturation plays a role in seasonal differences. And fourth, nested within this study is the calibration of a short form version of the CDPS dietary collection method. This study assesses this short form as a possible low-cost substitute data collection tool for tracking fruit and vegetable intake. Using identical CDPS methods, 8,543 telephone interviews were collected between November 2000 and October 2002. Sample sizes for each month of the year were approximately equal and included over-samples of low-income persons in the three race/ethnic groups of interest and of African Americans and Latinos in general. Interviews were conducted in both English and Spanish, and Latinos were further categorized into highand low-acculturation segments. Half of the overall sample was randomly assigned to answering three questions directly asking for the number of servings of fruit, fruit juice, and vegetables consumed on the previous day. These were asked ahead of the more extensive and detailed CDPS questions in order to avoid positive recall bias. Findings indicate that seasonality is not a factor in California for the adult population for the total number of servings of fruit and vegetables consumed, or separately for servings of fruit or servings of vegetables.

For the race ethnic groups in this study, this finding is the same for Whites and for Latinos. Additionally, no seasonality effects are seen for high-acculturation Latinos, however, results for low-acculturation Latinos are inconclusive. African Americans do have significant variation among months, mostly attributed to the month of December where there are large and significant intakes of servings of total fruit and vegetables and of servings of vegetables. However, since December is excluded from the usual CDPS data collection period, this finding is not a factor in interpreting CDPS data. For African Americans, although there appears to be some variation, there are no significant differences observed across the months of July through November, the months when CDPS African American samples and over-samples have been collected in the past. The overall conclusion is that there are no major month-to-month seasonality effects during the usual period of data collection for the CDPS for all adults, or specifically for Whites, African Americans, Latinos, and the low-income segments of these three race/ethnic groups. A noteworthy caveat is that these findings suggest, somewhat surprisingly, that the monthly patterns may be different from year to year. There is no explanation for this. Since this study only included two years of data, there is insufficient evidence to confirm this finding. Interpretation of CDPS trend data since 1989 can eliminate seasonality as an explanatory factor if patterns of monthly variation from July though October are assumed to be the same from year to year. This study suggests that this is the case.

Results comparing the SF3 with the CDPS method in measuring the number of servings of total fruit and vegetables show that the SF3 correlates positively and somewhat strongly . However, the SF3 was found to overestimate the number of servings of total fruit and vegetables by a little more than one-third of a serving . Among the three race ethnic groups studied, that overestimation is only slightly higher for African Americans . Since few surveys have sample sizes that can statistically differentiate groups at a level below half a serving, the SF3 appears to be a very good approximation of the number of servings of fruit and vegetables for population estimates in relation to the CDPS method. The conclusion is similar for estimating the number of servings of fruit. The degree of overestimation of the number of servings of fruit for all adults is higher than that for total fruit and vegetables, however, it is still less than half a serving . In estimating the number of servings of vegetables, the SF3 performed best in that there is no significant difference from estimates made using the CDPS method either for all adults or for any of the race/ethnic groups measured. The correlation is also good , although not as strong as that observed for fruit or for total fruit and vegetables. Although the point estimate for servings of vegetables in this study was not statistically different from the CDPS estimate, the lower correlation suggests the SF3 vegetable estimate will not track as well over time as the estimates for fruit alone or for total fruit and vegetables, both of which have relatively stronger correlations with the CDPS estimates. However, compared to dietary studies in general, all these correlations are still very good. In place of the CDPS method, the SF3 is a very good and potentially cost efficient way to obtain population estimates of the number of servings of fruit and vegetables. It should work well to track intake over time, but would likely produce a slightly higher estimate than that produced by the CDPS method. It is a good estimator of the number of servings of fruit. Estimates of the number of servings of vegetables,plastic plant pot although not as strongly correlated, should not be very different than those produced using the CDPS method. The California Dietary Practices Survey is conducted by the Cancer Prevention and Nutrition Section of the California Department of Health Services and the Public Health Institute to measure and track fruit and vegetable intake in the California population. Since its inception in 1989, the CDPS has been carried out every other year. From 1993 onward, an over-sample of Latino adults has been included, and since 1995, over-samples of low-income persons and low-income African Americans have been conducted. The CDPS is nationally recognized as the oldest, state-specific tracking survey for fruit and vegetable intake in the country.

In 2005 it will represent sixteen years of bi-annual survey data using a modified 24-hour recall telephone interview methodology. The results of this California Fruit and Vegetable Intake Calibration Study will enhance both the interpretative dimensions of past and future CDPS findings. Trends among White, Latino, and African-American groups have been a major focus of the CDPS.1 Between 1989 and 2001, the trend for the overall state estimates was relatively stable, starting at 3.8 servings in 1989 to 3.9 in 2001 . The highest estimate was 4.1 servings for 1995, dropping back to 3.8 in 1997 and 1999 and 3.9 in 2001. Among the majority White population, the trend mirrors the statewide trend. After an initial increase from 3.7 to 4.0 in 1991, the estimate has remained relatively flat at 3.9 servings per day, going to 4.0 in 2001. A much more pronounced increase has been observed among California’s Latino population. Starting relatively high at 3.9 servings in 1989 that increased to 4.7 in 1995 then fell almost a full serving to 3.8 in 1997 and returning to 3.9 in 2001. The trend among African Americans evokes even more concern because of its seemingly clear negative direction for a number of years. After an initial increase from 4.0 servings to 4.3 in 1991, each subsequent estimate has been lower. After a drop to 3.7 in 1993 it remained stable and lower at around 3.1 or 3.2 since 1997. A simple linear regression line fitted to these estimates for each race/ethnic group appears slightly positive for Whites and for Latinos, and negative for African Americans . However, the actual trend line or slope for Whites and for Latinos is technically flat, i.e., not statistically different from zero. The slope or trend line for African Americans is significantly negative . For a reasonable scientist, these observations also raise the question of a possible methodological or measurement flaw in the CDPS design. If only the statewide general population estimates were being made, the trend line appears believable even if discouraging when measured against the more than 10 years of effort by the 5 a Day—for Better Health! campaign. The race/ethnic subgroups, however, suggest another story. The question remains, how believable are these trends? Are there some critical adjustments not being made to these important data? If there is a race/ethnic difference, can a more precise difference be quantified? How much is the limited sample size of past surveys a contributor to these observations? Are the implementation methods suspect with regard to seasonal timing? One issue of possible measurement error may exist from the inherent logistic difficulties in obtaining past over-samples of Latino, African American, and low-income persons. To the best possible extent, the CDPS has been conducted mostly during the same months of the year, generally between July and October. Although conducting the survey in the same window of time each year is the operative objective, for a variety of funding-related administrative reasons, this has not always been possible. The actual data collection periods for the past seven surveys have been somewhat different. The 1989 survey occurred the earliest , while the 1993 survey ended the latest . Four surveys covered similar periods starting sometime in July-August and ending in September-October. This is also true for CDPS VI, because it finished data collection on November 2, 2001, making the effect of any cases in November negligible . The question arises whether or not there is a dimension of seasonal variation not accounted for in the CDPS estimates, especially in CDPS I and III. Equally important to acknowledge is that the more time consuming, “more difficult to reach” over-samples extended their data collection as much as four to six weeks beyond the end month for the general population shown in Exhibit 3 for CDPS III-VII. This places the Latino and much of the low-income African American data collection far outside the California “summer” period. These groupshave had their data collected well into the month of November when perhaps fruit and vegetable intake may be seasonally lower. Although fruits and vegetables are available throughout the year in the California, their cost is seasonally affected. This research examines if any seasonal variation exists for each of the racial/ethnic groups, both generally and for their low-income cohort. Seasonal variability in dietary intake has been recognized and measured using intake instruments other than the CDPS telephone interview method, but not for California alone.This study also measures seasonal differences among California’s Latino population based on different levels of acculturation.

The ancestral reconstruction allows us to consider the second question posed earlier: is the donor consistent with the X. fastidiosa subsp. fastidiosa genotypes found in the United States? The answer is very clearly “no.” The original donor carried cysG12 and holC19 . These alleles are both found in isolates from Central America, but no X. fastidiosa subsp. fastidiosa isolate found in the United States comes close to matching this criterion: the most similar U.S. ST has a 12-bp mismatch. There has been extensive sampling of X. fastidiosa subsp. fastidiosa within the United States, based on 85 isolates sampled across the United States from 15 different host plants . There is very little variation within X. fastidiosa subsp. fastidiosa isolates from the United States, consistent with the hypothesis that all X. fastidiosa subsp. fastidiosa isolates currently found in the United States are derived from a single strain introduced from Central America . Based on these data, we conclude that the X. fastidiosa subsp. fastidiosa donor was introduced into the United States from Central America and recombined with a native X. fastidiosa subsp. multiplex genotype similar to ST45; however, this donor lineage of X. fastidiosa subsp. fastidiosa was ultimately unsuccessful and died out. We can never conclusively prove the absence of this genotype from North America. However, X. fastidiosa has been extensively sampled from many plant species throughout the United States, and no isolates of X. fastidiosa subsp. fastidiosa have been found that carry alleles similar to the inferred donor alleles cysG12 and holC19 ; indeed all X. fastidiosa subsp. fastidiosa isolates so far found in the United States are consistent with the introduction into the United States of just a single genotype . The transient presence of the donor genotype is consistent with a single large-scale introgression event founding the recombinant group. This raises the possibility that conjugation might have been involved; however, if this was the case,10 plastic plant pots the genomic DNA was broken into pieces prior to homologous recombination, since the data show short regions of recombination.

The data from the MLST loci plus pilU show 7 significant recombination events , and 3 of them included at least one recombination break point. Since these loci range in length from roughly 400 to 700 bp, this result would be consistent with an average recombination length of no more than a few kb, similar to the 2.6-kb average length observed by Nunney et al. in a comparison of two X. fastidiosa subsp. fastidiosa genomes . Similarly, the regions identified from the data of Parker et al. showed the same pattern, with a high proportion of recombination breakpoints identified within the sequenced loci . In this context, it is important to note that Rogers and Stenger have found a conjugative plasmid in X. fastidiosa. Furthermore, a high rate of transformation has been demonstrated in the lab , and it has been shown that this process can result in efficient recombination with only a few hundred bases of homologous sequence . Both conjugation and transformation may have been involved in the evolution of the recombinant group, since the data raise the possibility of both large-scale intersubspecific and smaller-scale intrasubspecific recombination . The results support the general conclusion that successful recombination is a rare but important event, a possibility emphasized by Wiedenbeck and Cohan in their review of bacterial adaptation to new environments. However, given the high rates of recombination observed experimentally in X. fastidiosa , this rarity is somewhat surprising, perhaps suggesting that in X. fastidiosa the majority of intersubspecific recombination events fail due to their negative fitness consequences. Fitness loss due to recombination is consistent with the high level of plant host specificity observed among the genotypes of X. fastidiosa . On the other hand, it is clear that recombination can create combinations that are beneficial to the species, enabling it to invade new plant hosts. Specifically, the successful invasion of blueberry and blackberry appears to have resulted from large-scale recombination between two subspecies, a pattern that appears to be repeated in the invasion of mulberry . Furthermore, Nunney et al. suggested that introgression into X. fastidiosa subsp. pauca in South America from a donor may have enabled X. fastidiosa subsp. pauca to infect citrus, causing the economically devastating disease of citrus variegated chlorosis.

This would help explain why CVC did not appear in Brazil until the 1980s , despite the presence of the native pathogen and vectors ever since citrus was introduced several hundred years ago. These observations raise an important concern: that mixing of genetically divergent forms of the same species can result in recombinant forms capable of invading new niches—in this case, new plant hosts. Thus, the presence of a pathogen in an area should not lead to the assumption that further introductions will cause no further harm; in fact, as a result of recombination, further introductions may result in a qualitative worsening of the problem.Highbush blueberries , native to the northeastern United States, are important commercial fruit and are the most planted blueberry species in the world . In the United States, blueberries traditionally have been grown in cooler northern regions; however, the development of new southern cultivars with low chilling-hour requirements has made possible the expansion of blueberry production to the southern United States and California .Blueberry production in California was estimated in 2007 at around 4,500 acres and is rapidly increasing. Common southern cultivars grown include ‘Misty’ and ‘O’Neal’, but other improved southern high bush cultivars are now being grown from Fresno southward, such as ‘Emerald’, ‘Jewel’ and ‘Star’ . Southern high bush “low-chill” cultivars are notable for their productivity, fruit quality and adaptation , and require only 150 to 600 chillhours, making them promising cultivars for the San Joaquin Valley’s mild winters . Since 1998, we have conducted long-term productivity and performance evaluations of these cultivars at the University of California’s KearneyAgricultural Center in Parlier . North American production of high bush blueberry has been increasing since 1975, due to expansion of harvested area and yields through improvements in cultivars and production systems. In 2005, North America represented 69% of the world’s acreage of high bush blueberries, with 74,589 acres producing 306.4 million pounds . Acreage and production increased 11% and 32%, respectively, from 2003 to 2005. The U.S. West, South and Midwest experienced the highest increases in acreage. In 2005, 63% of the world’s production of high bush blueberries went to the fresh market. North America accounts for a large part of global high bush blueberry production, representing 67% of the fresh and 94% of the processed markets . Blueberry consumption is increasing, which is encouraging increased production. As a result, fresh blueberries are becoming a profitable specialty crop, especially in early production areas such as the San Joaquin Valley .

In general, a consumer’s first purchase is dictated by fruit appearance and firmness . However, subsequent purchases are dependent on the consumer’s satisfaction with flavor and quality, which are related to fruit soluble solids , titratable acidity , the ratio of soluble solids to titratable acidity, flesh firmness and antioxidant activity . The sugars of the larger high bush blueberry cultivars that are grown in California are fructose, glucose and traces of sucrose. Lowbush blueberries — which are wild, smaller and grow mostly in Maine — lack sucrose. . The composition of organic acids is a distinguishing characteristic among species. In high bush cultivars, the predominant organic acid is usually citric , while the percentages of succinic, malic and quinic acids are 11%, 2% and 5%, respectively. However, in “rabbiteye” blueberries the predominant organic acids are succinic and malic, with percentages of 50% and 34%, respectively, while citric acid accounts for only about 10% . These different proportions of organic acids affect sensory quality; the combination of citric and malic acids gives a sour taste,plastic pots large while succinic acid gives a bitter taste . In addition to flavor, consumers also value the nutritional quality of fresh fruits and their content of energy, vitamins, minerals, dietary fiber and many bio-active compounds that are beneficial for human health . Fruits, nuts and vegetables are of great importance for human nutrition, supplying vitamins, minerals and dietary fiber. For example, they provide 91% of vitamin C, 48% of vitamin A, 27% of vitamin B6, 17% of thiamine and 15% of niacin consumed in the United States . The daily consumption of fruits, nuts and vegetables has also been related to reductions in heart disease, some forms of cancer, stroke and other chronic diseases. Blueberries, like other berries, provide an abundant supply of bio-active compounds with antioxidant activity, such as flavanoids and phenolic acids . For example, a study performed in rats showed that when they were fed diets supplemented with 2% blueberry extracts, age-related losses of behavior and signal transduction were delayed or even reversed, and radiation-induced losses of spatial learning and memory were reduced . Some studies have shown that the effects of consuming whole foods are more beneficial than consuming compounds isolated from the food, such as dietary supplements and nutraceuticals. Because fruit consumption is mainly related to visual appearance, flavor and antioxidant properties, we decided to evaluate fruit quality attributes, antioxidant capacity and consumer acceptance of the early-season blueberry cultivars currently being grown in California. We characterized the quality parameters of six southern high bush blueberry cultivars grown in the San Joaquin Valley for three seasons , and evaluated their acceptance by consumers who eat fresh blueberries.For the quality evaluations at UC Kearney Agricultural Center, we used three patented southern high bush blueberry cultivars — ‘Emerald’ , ‘Jewel’ and ‘Star’ , and three non-patented cultivars — ‘Reveille’, ‘O’Neal’ and ‘Misty’. The plants were started from tissue culture and then grown for two seasons by Fall Creek Farm and Nursery in Lowell, Ore. Before planting these cultivars in 2001, the trial plot was fumigated to kill nut grass .

Because blueberries require acidic conditions, the plot’s soil was acidified with sulfuric acid, which was incorporated to a depth of 10 to 12 inches with flood irrigation, resulting in a pH ranging from 5.0 to 5.5. A complete granular fertilizer was broadcast-applied at a rate of 400 pounds per acre . The plants were mulched with 4 to 6 inches of pine mulch and irrigated with two drip lines on the surface of the mulch, one on each side of the plant row. Irrigation frequency was two to three times per week in the spring and daily during June and July. The emitter spacing was 18 inches , with each delivering 0.53 gallon per hour of water acidified with urea sulfuric acid fertilizer to a pH of 5.0. The plot received an application of nitrogen in the first season, as well as in subsequent growing seasons. The rate was 80 pounds nitrogen per acre at planting, 60 pounds the second year, 90 pounds the third year and 120 pounds the fourth year. Annual pest control was limited to one application of Pristine fungicide in February for botrytis management, and two or three herbicide treatments of paraquat . In year three, the plants received one insecticide treatement of spinosad for thrips management. Twenty-eight plants per cultivar were planted in a randomized block design using seven plants per block as an experimental unit, replicated in four rows. Rows were spaced 11 feet apart, with the plants in the rows spaced 3 feet apart, with a space of 4 feet between plots. Fruit was harvested at times when it would have been commercially viable if it had been in a commercial field. Fruit from each of the seven plant blocks was harvested and a composite sample of 80 random berries per each replication was used for quality evaluations.Berries were randomly selected from each replication for quality evaluation at the first harvest time for each respective season . During the 2007 season, in addition to the initial quality evaluations, harvested berries were stored at 32°F in plastic clam shells, and measured for firmness 15 days after harvest and for antioxidant capacity 5, 10 and 15 days after harvest. Three replications per cultivar were measured for each quality parameter. The initial firmness of 10 individual berries per replication was measured with a Fruit Texture Analyzer. Each berry was compressed on the cheek with a 1-inch flat tip at a speed of 0.2 inch per second to a depth of 0.16 inch and the maximum value of force was expressed in pounds force .

Power analysis from a larger set of black spruce tree ring increments from three stands in Interior Alaska , indicated that as few as four tree ring widths could be used to estimate site ANPP within a 95% confidence interval. Such a low sampling intensity for tree rings may be a reflection of the even-aged, structurally simple nature of black spruce forests. The mean of the average annual ring width for the last 10 years was used with the stem allometry equation to calculate secondary growth for each tree measured in the inventory. Stand biomass was also calculated with our inventory but regional Alaskan or Canadian equations , and these values were compared to estimates derived from the local equations.Above ground biomass of vascular plants, mosses and lichens was measured across all sites by destructive harvest in July 2001 at approximately peak biomass. To more closely examine the dynamics of regrowth in the first several years after fire, biomass was also measured in the 1999 dry site 2 months after the fire as well as mid-summer in 2000–2002; it was also measured in 2000, 2001, and 2002 in the mature dry site for comparison. Trees less than 1.37 m in height that were excluded from the inventory described above were included in these harvests. In harvests of the 1999 dry site, we determined whether each species was a re-sprouter by assessing the presence of charred stems or large rhizomes. We also monitored species or generic richness on an annual basis in these sites by recording the presence of all species within a 144-m2 plot surrounding the 1 m2 harvest blocks. We did not survey species richness in the other sites. In each site, above ground biomass was clipped from either 6 or 12 randomly located 1 m2 quadrats. In the mesic chronosequence sites and the 1987 dry site,blueberry container size above ground biomass of vascular species was clipped from six 1 m2 quadrats randomly located along two 100 m long permanent transects .

Mosses and lichens were collected from a 400-cm2 organic soil plug sawed from a randomly selected corner of the 1 m2 quadrat following vascular plant clipping. In the 1987 dry site and the 1994 mesic site, we also harvested tall shrubs in a 4-m2 quadrat surrounding the 1-m2 quadrat to account for their larger stature. Vegetation was harvested similarly in the 1999 and 1921 dry sites, except that 12 quadrats were harvested. Samples were returned to the lab and sorted into species and tissues within 1 day of harvest. Each vascular species was separated into several tissue categories including current year and previous year leaves, current year and previous year stems, and fruits or inflorescences following methods modified from Shaver and Chapin and Chapin and others . Mosses were separated to species and lichens to genera. We included all structurally intact moss and lichen tissue in the live biomass category. This was determined by tugging gently on the brown part of the moss or lichen ramet; the part that broke off was determined to be litter. Large samples were chopped into small pieces, mixed, and then sub-sampled for fresh and dry weights. Tissues were then dried at 60 C for 48 h or more before weighing. Above ground vascular net primary production was estimated as the sum of the current year‘s apical growth, including leaves and stems. We did not measure secondary growth for under story plants and thus our ANPP values represent an underestimate for shrubs where secondary growth is likely important, mainly Salix spp. and trees less than 1.37 m tall. Apical growth was defined as that produced from apical or intercalary meristems during the current growing season; it was calculated by summing the masses of all current year‘s leaf, stem, and reproductive tissues in the quadrat harvested. Harden and others measured moss production in these sites by measuring the apical growth of individual species and then scaling growth to the plot level with digital mapping. At each site, an average of ten 60 · 60 cm2 moss plots were arranged along greater than 100 m transects with plots spaced every 20–40 m. Percent cover values for up to five dominant moss species within each plot were recorded in fall 2001 via digital photos, extensive field notation, and digitization with Arcview 8.0 software .

Apical growth for each species within each plot was based on growth between June and September of 2001. Within each plot, 10 cm2 dense, generally single-species patches of moss were dyed with a fluorescent brightener in early June. Sprayed moss samples were harvested in late September using a coring device of known area and refrigerated until measurement. Apical growth of each ramet was measured individually under a black light using calipers and new growth was harvested, dried, and weighed to estimate per ramet production. The density of stems per m2 was determined from the % cover plots described above. Moss NPP per species was then estimated on a per plot basis as the mass of apical growth per ramet times the ramet density per unit area times the areal coverage. To validate this method of estimating moss NPP, Harden and others compared estimates of H. splendens productivity to estimates based on a morphological growth marker . They found that the fluorescent dye method underestimated H. splendens production relative to the morphological method, possibly due to an offset in the timing of harvest of the two methods. We have chosen to report the fluorescent dye methods here because these estimates likely represent the most conservative estimate of moss NPP.In the 1999 dry site where we followed growth for 4 years, ANPP was surprisingly resilient to fire disturbance and returned to the level of the mature 1921 dry stand by year four despite radical changes in species composition. Treseder and others observed that root length production was not different between these two sites in 2002, suggesting that below ground production was similarly resilient. The re-sprouters that dominated post-fire productivity must have had roots and/or rhizomes buried in deep organic or mineral soil because over 70% of organic soil depth was consumed in the fire . Rhizomes and roots may have been lingering in mineral soil since the last burn, which is a pattern observed for grasses in black spruce/feather moss sites , as well as trembling aspen which may re-sprout from root suckers after fire . Species known to root in the organic layer dominated pre-fire under story biomass, namely blueberries and cranberries ; these species recovered slowly after fire in the 1999 dry site.

The 1999 mesic site had substantially thicker organic soil layers both before and after fire then the 1999 dry site . Blueberry biomass was not different but ANPP was twice as large in the 1999 mesic site then in the mature mesic chronosequence site . Cranberries, by contrast,growing raspberries in container had 93% less biomass in the 1999 than in the 1886 mesic site, which may be due to the fact that their rhizomes tend to be only 2–3 cm deep in the moss litter layer , whereas blueberries tend to root in the fibric layer . Most important in the rapid recovery of ANPP after fire appears to be the survival of key species, which may, in part, be related to whether meristems are protected in unburned layers of soil. Other factors that likely contribute to the rapid rate of ANPP recovery include increased resource availability due to release of N and P via combustion , decreased competition , warmer soils stimulating microbial decomposition and mineralization of nutrients from soil organic matter , and more available moisture due to reduced evapotranspiration . Across all sites, ANPP was highest in the 1987 dry site where deciduous trees and shrubs dominated biomass and production. Aspen and willow resprouts were present in the 1999 dry site , and stems of dying or dead aspen and willow were visible in the dry mature site , so it is plausible that these sites are part of a successional trajectory that includes co-dominance of black spruce with deciduous trees during mid-succession . In the mesic chronosequence, deciduous trees and tall shrubs were present but at low abundance in intermediate aged sites and were absent from the mature site. Therefore, in contrast to the dry chronosequence, the mesic sequence may represent self-replacement, or spruce-to-spruce successional trajectory . Fire severity, drainage and soil temperature have been identified as factors driving the abundance of aspen and tall shrubs in Interior Alaska. Aspen density was positively related to fire severity in a nearby mesic site that burned in 1994 and aspen and willow were more abundant in more frequently burned sites in the Yukon presumably due to the better survivorship of species with rhizomes and roots in the mineral soil. Across the landscape, single species stands of aspen are found in relatively warm, well-drained sites . Severe or frequent fires can increase soil temperature though the removal of insulating moss and soil organic matter and increase drainage through thermal erosion of permafrost. Thus, the high abundance of deciduous tree and tall shrub species in the 1987 dry site could be related to thermal effects of severe fire or alternatively, the site could just be an anomalously warm, well drained patch of the landscape.

Finally, stochastic processes such as the proximity to seed sources could play a role in the establishment of deciduous species as well and cannot be ruled out as a factor contributing to compositional differences between the chronosequences. Black spruce density, basal area, biomass and ANPP in the mature sites were within the range reported for Interior Alaska . Biomass in our mesic 1886 stand was 90% of peak black spruce biomass estimated from large-scale forest inventory measurements across the state of Alaska , suggesting that this stand may be at or near peak biomass. The mature dry stand, by contrast, accumulated 78% of biomass predicted for its age class . If the biomass accumulation curve for this chronosequence is projected to 150 years estimate of maximum stand biomass, peak biomass would be 2,831 g m)2 ; still substantially less than peak biomass in the mesic chronosequence. Lower black spruce biomass and ANPP in the mature dry site than in the mature mesic site appears to be driven primarily by higher tree density in the latter site because biomass and ANPP per tree were similar between sites . Yarie and Van Cleve similarly found black spruce production to be constant over variably drained stand ages ranging from 50 to 150 years when productivity was standardized to full stocking rate. Lower density in the mature dry than in the mature mesic site could be related to processes directly attributable to drainage, such as self thinning due to water competition , interactions with abundant deciduous tree species or feedbacks between fire and drainage . Alternatively, differences in density could be caused by processes that are relatively independent of drainage, such as climatic extremes during the sensitive early years of spruce seedling establishment. Our 1956 mesic site had only 25% of the tree density of the 1886 mesic site and contained only 16% of black spruce biomass predicted for its age class by Yarie and Billing‘s accumulation curve. Because upland black spruce stands tend to be comprised of a single cohort , it seems unlikely that density will quadruple in the next 50 years. These differences in density, then, may represent poor site matching in the mesic chronosequence and confound estimates of biomass accumulation and ANPP. To explore the impact of this on our biomass estimates, we multiplied per tree biomass of the 1956 mesic site 1 by density of the mature mesic site , yielding an estimate of 1,135 g m2 , which is within 10% of Yarie and Billing‘s estimate for this age class. When this value was plotted on our chronosequence biomass accumulation curve , the curve is still best-fit by a linear equation 169.4, R2 = 0.97, P = 0.01, suggesting that the functional shape of biomass accumulation would still differ between mesic and dry chronosequences if density was held constant across the mesic chronosequence. Our Alaskan black spruce stands had less biomass and were less productive than comparable well drained stands in Manitoba, Canada, due to both lower tree density and lower per tree biomass and growth.

Many human studies reporting positive health outcomes have used freeze-dried wild blueberry powder, which is a natural source of concentrated polyphenolics. However, the freeze-dried WBB powder may be tart or astringent and not always palatable to consume. This can be problematic in feeding trials in children and adults. In our previous work, we developed five food products prepared with freeze-dried WBB powder that were evaluated for children’s acceptability and desire to eat. These results are useful in designing food products as well as menu items that could be used in clinical trials of WBB-rich diets. In addition to evaluating sensory properties, it is important to validate the storage stability of polyphenolics in these products, before use in clinical trials, to ensure that a consistent dose of polyphenolics can be maintained. Blueberry polyphenolics, especially anthocyanins, are unstable in various processed forms such as juices, jams, purees, and canned berries when stored at ambient temperature. Additionally, anthocyanins in freeze-dried WBB powder are susceptible to degradation when stored at ambient temperature with a reported half-life of 139 days at 25 ◦C. The mechanism responsible for loss of anthocyanins during storage is unknown, but anthocyanin losses are commonly accompanied by increased polymeric color values, suggesting that anthocyanins form polymers with proanthocyanidins. In addition to polymerization, many other factors can affect the stability of anthocyanins including exposure to elevated temperatures, light, oxygen, metals, sugars, and ascorbic acid. At present, refrigeration of blueberry products such as jam and juices is the best approach to mitigate polyphenolic losses during storage. This study was undertaken to determine the stability of anthocyanins, flavonols, plastic potting pots chlorogenic acid, and percent polymeric color in five blueberry products prepared with freeze-dried WBB powder.

Gummy, oatmeal bar, graham cracker cookie, and juice were stored at 21 ◦C and 4.4 ◦C and evaluated for anthocyanin, flavonol, and chlorogenic acid content and percent polymeric color over eight weeks of storage. An ice pop product stored at −20 ◦C was evaluated for its anthocyanin and chlorogenic acid content over eight weeks of storage. Samples of juice, ice pop, gummy, oatmeal bar, and graham cracker cookie, each containing 15 g of WBB powder per serving, were prepared and packaged as previously described. One serving of oatmeal bar, ice pop, and graham cracker cookie was equivalent to one piece each , a juice serving was 135 g, and a gummy serving was 7 pieces, or 113 g. The amount of 15 g of WBB powder used in product formulations was calculated and converted from previous animal studies to humans. This involved only the use of brief microwave heating to solubilize the ingredients in order to avoid thermal loss of phenolic compounds, but still obtain a ready-to-consume non-baked product. The blueberry juice and ice pop were prepared with an anthocyanin concentrate, previously extracted from the WBB powder. This procedure was used to produce juice and ice pop products with no particulates. The formulation was adjusted with water so the anthocyanin content ofthe products was equivalent to that found in 15 g of WBB powder per serving. The preparation and processing of the samples for the storage study were performed in two separate experiments, using the same sample of wild freeze-dried blueberries obtained from FutureCeuticals Inc. . The WBB powder was stored at 15.5 ◦C for four months between the two experiments. The samples from Experiment 1 were stored at 21 ◦C and the samples from Experiment 2 were stored at 4.4 ◦C. The ice pop products prepared in Experiment 1 were stored at −20 ◦C. Three samples of each packaged product were evaluated at time 0 and after 2, 4, 6, and 8 weeks of storage.

Polyphenolics were extracted by homogenizing 5 g of WBB-containing food product or 1 g of WBB powder in 25 mL of extraction solution containing methanol/water/formic acid , to the smallest particle size using a Euro Turrax T18 Tissuemizer for 1 min. Homogenates were centrifuged for 5 min at 10,864 × g. The pellet was re-extracted two additional times with 25 mL of extraction solution and centrifuged for 5 min at 10,864 × g. The filtrates were pooled and adjusted to 100 mL with extraction solvent in a volumetric flask. Prior to HPLC analysis, 5 mL of extract were dried in a Thermo Savant Speed Vac Plus SC210A and reconstituted in 1 mL 5% formic acid in water. All samples were passed through 0.45 µm nylon syringe filters into 1 mL HPLC vials prior to HPLC analysis. The ice pop and juice samples did not undergo extraction due to prior extraction of anthocyanins to make the concentrate used in the formulation but were filtered using the 0.45 µm nylon syringe filters prior to HPLC analysis. Anthocyanins and chlorogenic acid were analyzed by HPLC using the method of Cho and others. Samples were analyzed using a Waters HPLC system equipped with a model 600 pump, a model 717 Plus autosampler, and a model 996 photodiode array detector. Separation was carried out at room temperature using a 4.6 mm × 250 mm Symmetry C18 column preceded by a 3.9 mm × 20 mm Symmetry C18 guard column. The mobile phase was a linear gradient of 5% formic acid and methanol from 2% B to 60% B for 60 min at a flow rate of 1 mL/min. The system was equilibrated for 20 min at the initial gradient prior to each injection. Detection wavelengths of 320 nm and 510 nm were used to monitor chlorogenic acid and anthocyanin peaks, respectively. Individual anthocyanin monoglucosides and acylated anthocyanin derivatives were quantified as delphinidin, cyanidin, petunidin, peonidin, and malvidin glucoside equivalents using external calibration curves of a mixture of authentic standards .

Chlorogenic acid was quantified using external calibration curves of an authentic standard . Results are expressed as mg of anthocyanin or chlorogenic acid per g of WBB powder. Flavonols were analyzed by HPLC using the same HPLC system described above according to the method of Cho et al.. Separation was performed at room temperature on a 4.6 mm × 250 mm Aqua C18 column preceded by a 3.0 mm × 4.0 mm ODS C18 guard column. The mobile phase was a linear gradient of 2% acetic acid and 0.5% acetic acid in water and acetonitrile from 10% B to 55% B in 50 min and from 55% B to 100% B in 10 min at a flow rate of 1 mL/min. The system was equilibrated for 20 min at the initial gradient prior to each injection. A detection wavelength of 360 nm was used to monitor flavonol peaks. Flavonols were quantified as rutin equivalents using an external calibration curve of an authentic standard , with results expressed as mg of rutin equivalents per g of WBB powder.An analytical Hewlett Packard 1100 series HPLC instrument equipped with an autosampler, binary HPLC pump,raspberry container growing and UV/Vis detector was used. For HPLC/MS analysis, the HPLC apparatus was interfaced to a Bruker model Esquire-LC/MS ion trap mass spectrometer . Mass spectral data were collected with the Bruker software , which also controlled the instrument and collected the signal at 520 nm. Typical conditions for mass spectral analysis conducted in positive-ion electrospray mode for anthocyanins and negative-ion electrospray mode for flavonols included a capillary voltage of 4000 V, a nebulizing pressure of 30.0 psi, a drying gas flow of 9.0 mL/min, and a temperature of 300 ◦C. Data were collected in full scan mode over a mass range of m/z 50−1000 at 1.0 s per cycle. Characteristic ions were used for peak assignment. For compounds where chemical standards were commercially available, retention times were also used to confirm the identification of components. The effect of storage time on anthocyanins, flavonols, chlorogenic acid, and % polymeric color in each blueberry product was evaluated using the Fit Model platform of JMP, and the percent retention of each compound after 8 weeks of storage was calculated using the fit model equation. The effect of storage temperature on phenolic compounds stability was not evaluated in this study due to the length of time the WBB powder was stored between processing the products in Experiment 1 and Experiment 2 . During this four-month storage time, the powder stored at 15.5 ◦C presumably absorbed moisture evident by powder clumping, resulting in different amounts of polyphenolics in the products immediately after processing.

Principal component analysis was performed with the total and individual anthocyanins variables, using the Multivariate platform in JMP, on the mean value of each sample per time point and using the correlation method. Correlations among total anthocyanins and percent polymeric color were determined by pairwise correlations method in the multivariate platform of JMP.The WBB powder used to prepare the products contained at least 22 anthocyanins , which were identified by comparing their mass-to-charge values and elution orders with previous studies. Blueberries are unique in that three different sugars are commonly attached to the five anthocyanidins. This was confirmed in our study; however, we were unable to detect peonidin-3-arabinoside using our HPLC method. We were unable to obtain complete separation of all of the anthocyanins present in the extract due to the complexity of the anthocyanin profile. Peak 15 contained two co-eluting compounds, namely cyanidin-3- galactoside and cyanidin-3- galactoside, and peak 18 was composed of three co-eluting compounds, namely delphinidin-3-rutinoside, cyanidin-3- glucoside, and malvidin-3- galactoside. We were unable to identify peak 17, which appeared to be a delphinidin derivative based on its aglycone m/z of 303, but the molecular ion m/z value was ambiguous. Many of the anthocyanins were present in acylated form. Two of the cyanidin glycosides were acylated with malonic acid, whereas delphinidin, cyanidin, and malvidin galactosides as well as petunidin, peonidin, and malvidin glucosides were acylated with acetic acid moieties. The total anthocyanin content of the ice pop over eight weeks of storage at −20 ◦C is shown in Figure 1. The total amount of anthocyanins significantly decreased with storage time , but the percent retention remained high with 93% of total anthocyanins retained in the product after eight weeks. Consistent with our results, total anthocyanin content of frozen blueberries was stable over three months of storage at −20 ◦C . Changes in major individual anthocyanins in the ice pop over eight weeks of storage at −20 ◦C are shown in Figure S1. Most of the individual anthocyanins did not significantly decrease over storage. For the anthocyanins that decreased during storage, their percent retention after eight weeks remained over 87%: malvidin-3-glucoside , malvidin-3-galactoside , cyanidin-3-galactoside , malvidin-3- glucoside , petunidin-3-glucoside .The total anthocyanin content of the juice decreased with storage time for each storage temperature . The total anthocyanin content of juice stored at 4.4 ◦C and 21 ◦C is shown in Figure 2. After eight weeks of storage, the juice stored at 4.4 ◦C retained 90.7% of total anthocyanins compared with control samples , whereas the juice stored at 21 ◦C retained 69.1%. Concentrations of anthocyanins are known to readily decline during storage of blueberry juice at ambient temperature, but refrigeration is an effective treatment to ameliorate anthocyanin losses. Changes in the major individual anthocyanins in the juice stored at 4.4 ◦C and 21 ◦C over eight weeks of storage are shown in Figure S4. At 4.4 ◦C, peonidin-3-galactoside, cyanidin-3-arabinoside, malvidin-3-galactoside, malvidin-3-glucoside, and malvidin-3- galactoside remained stable over the eight weeks of storage. At 4.4 ◦C, all anthocyanins showed >50% retention, with the minimal percent retention being 57.7% for the unknown delphinidin derivative. This compound, however, did not significantly decrease over storage at 21 ◦C, along with the two co-eluting anthocyanins galactoside + cyanidin-3- galactoside. Besides these two compounds, the percent retention of anthocyanins at 21 ◦C ranged from 59% glucoside to 75.5% . The total anthocyanin content of the gummy product decreased with storage time for each storage temperature . The total anthocyanin content of the gummy product stored at 4.4 ◦C and 21 ◦C is shown in Figure 2. After eight weeks of storage, the gummy product stored at 4.4 ◦C and 21 ◦C retained 43.2% and 50.6%, respectively, of their original total anthocyanin content . Consistent with our findings, levels of total anthocyanins declined in gelatin gels prepared with grape pomace extract over 24 weeks of storage at 21 ◦C, with losses most pronounced in gels exposed to neon light.

Cattle also went into the bottom land to get water, especially during droughts when large holes were dug into the riverbed to provide livestock and people with access to the perennial groundwater for drinking . Reclamation projects stimulated by new state laws promoting land use converted marshy areas around valley’s sloughs into agricultural land during 1850-1870 . According to records from American land surveyors and the British naturalist William Brewer who traveled the river corridor in the mid-1850s and early 1860s , the Salinas was a desolate, dry bed of wind-blown sand and treacherous quicksand at that time, yet newspapers also reported on devastating floods, such as in 1852 when the Salinas plain was inundated. Overall, a fundamental transformation in the landscape was wrought by Europeans, even as regional climate remained the same with no long term trend throughout that period , although the characteristic feature of the climate has been frequent recurrences of droughts and floods . Similar to the observed threshold change in sedimentary response to post-European land transformation in the Chesapeake Bay region , the pre-European Salinas landscape was likely resilient to natural climatic events , even with Ohlone fire practices, but after European land transformation the landscape became highly sensitive to perturbation.Today, the Salinas River is heavily changed due to modern land use and flow regulation. Excessive surface irrigation and the regional drought of 1880 were the major stimuli for the onset of groundwater pumping , fueled by the wood from the valley’s remaining trees. By 1901 pumping was well underway, with wells drawing water from as deep as 75 m below the ground surface and lowering the water table below the ground by 3-5 m . Agriculture is now the largest anthropogenic disturbance in the watershed in terms of area,blueberries in containers followed by urbanization and dam emplacement .

Three major dams were constructed on the mainstem and two major eastern tributaries from 1941–1965, impounding the runoff of some 1,970 km2 , or about 17% of the total watershed, primarily in the mountainous subbasins in the wetter western mountains . Urbanization has increased significantly in the basin over the past century but represented only ~2% of land area by 2010.The Salinas River watershed of central California was used as the test case for this study because of the preponderance of data documenting diverse hydrologic events in the watershed, and its history as a preeminent test bed for watershed-scale sediment flux over the last few decades. This work provided the initial forensic setting from which to explore the roles of wildfire and agricultural activity in a semi-arid, mountainous watershed. Previous studies found evidence for the primary role of the Salinas River in supplying sand to Monterey Bay and the significant reduction of coarse sediment export to the coast due to damming on the Salinas and neighboring Rivers . External controls on decadal to inter-decadal scale fluvial sediment flux patterns have been further investigated in terms of El Niño Southern Oscillation cycles . Integrated expressions of external and internal factors in the form of antecedent hydrologic conditions that are affected by ENSO have also been examined as controls on suspended sediment discharge regimes . One previous study has also addressed the importance of wildfire in controlling the sediment export from a major Salinas tributary . Inman and Jenkins conducted a regional scale study on suspended sediment flux from central and southern California coastal rivers with a focus on episodic events and their relationship to regional climate cycles.

They found that large events dominated sediment transfer from the rivers in this region, including the Salinas, and that decadal scale wet and dry cycles lead to concomitant increases and decreases in suspended sediment flux to the ocean. Their approach to calculating suspended sediment discharge through the lower Salinas utilized a rating curve constructed from data collected by the USGS gauge station near Spreckels, CA during water years 1969-1979, which they applied to monthly averages of daily water discharge from 1944-1995, resulting in an estimated average annual suspended sediment discharge of 1.7 Mt yr-1 . Farnsworth and Milliman also examined the role of large discharge events in the estimation of total suspended sediment load at gauge S1, and used the same set of S1 USGS data to compute a power law rating curve that was then applied to daily water discharge data from 1930-2000 for an average annual suspended sediment discharge of 3.3 Mt yr-1 . Gray et al.thoroughly investigated suspended sediment dynamics in the Salinas River in relation to climatic and hydrological drivers. It was found that CSS-Q behavior was influenced by antecedent hydrologic conditions at event, annual, interannual anddecadal time scales , and that the temporal trend in discharge-corrected suspended sediment concentrations was negative over the 1967-2011 period of record . Notably, no change in the relationship between precipitation and discharge was found over this time period . By taking these factors and the temporal dependence of sediment behavior into consideration, the average annual suspended sediment flux was estimated as 2.1 to 2.4 Mt . The Arroyo Seco drains ~ 700 km2 of the wetter western mountains in the Salinas River watershed. The majority of the Arroyo Seco remains largely undeveloped and is undammed, unlike the other major Salinas River subbasins in this region. For this reason, the Arroyo Seco is a significant contributor of water and sediment to the Salinas River .

Warrick et al.found that sediment export from the Arroyo Seco was highly controlled by the sequence of wildfire and subsequent high precipitation/discharge events. Nearly complete burning of the upper Arroyo Seco watershed in the summers of 1977 and 2008 facilitated a pairwise comparison of post fire sediment flux past gauge A3 , in relation to storm timing and intensity differences . A rare , high intensity wet season during the 1978 water year led to an annual sediment flux ~ 100x pre-fire, while moderate precipitation in 2009 and 2010 resulted in only 5x and 9x increases, respectively. Warrick et al.estimated that the Arroyo Seco’s post-fire sediment flux may have caused the total Salinas River sediment to export to double in 1978.Discharge and a number of fluvial constituents, including suspended sediments, are monitored in the lower Salinas River at S1 and S2 . This study was based on 286 suspended sediment samples collected by the USGS between 1967 and 2010 , and 44 by the authors between 2008 and 2011 from gauging stations S1 and S2 and the Davis Street bridge crossing 4 km downstream from S1 . Potential biasing of the suspended sediment data set in terms of hydrologic regime representation and temporal distribution was examined and discounted in Gray et al. . Paired samples were collected by the authors from the water surface at cross-channel stations of one-quarter, one-half, and three-quarters wetted channel width , which were then processed for CSS and particle size distribution as per Gray et al. . Suspended sediment samples for this study were collected from the surface of river flow. For this reason coarse suspended sediment particles were expected to be underrepresented. Geographical and temporal wildfire data recorded by the California Department of Forestry and Fire Protection Fire Resource Assessment Program from 1911- 2010 were clipped to the geographic extent of the Salinas watershed . Contributing areas behind dams were masked for the time periods of their operation,planting blueberries in pots as the trapping efficiency of these dams was previously estimated as > 90% for fine sediment . The areal extent of fires in undammed portions of the watershed was then summed by year for further computations of effective burn area . The lasting, time-dependent effect of a given wildfire, or set of wildfires, on the landscape can be modeled as “effective” burn area, which is the initial burn area modified by standard exponential decay functions operating over the elapsed time since the fire . The range of relevant half-life values for the EBA decay function found for semiarid southern California systems is between 0.5–14 years, with 1.4 years identified as the best fit for the Arroyo Seco . In this study the EBA approach was applied to annual burn area data with a range of t½ values from 0.5–10 years in 0.5 year steps. As most Salinas fires occur during hot, dry summers, the EBA associated with a given CSS sample was calculated by summing of effective burn area contributions from all previous years, with the year before the water year of the sample treated as t = 0, while the annual burn area from the water year of the sample was excluded.

Spatial coverage of crops by year from 1965-2011 was obtained from the Monterey County Agricultural Commissioner’s Office Crop Reports and sorted into ‘field’ and ‘row’ crops . Data on the areal coverage agriculture by irrigation technique from 1993-2010 and urbanization from 1984-2010 were extracted from Monterey County, 2015b.Testing for the control of wildfire and agricultural activity on sediment production in the lower Salinas River was based on comparing the temporal trends of LOESS residuals for both fines and sand with the temporal trends of metrics for effective wildfire burn area, bulk and crop specific agricultural areas, and areas under given irrigation types. Temporal trend analysis was conducted with Mann-Kendall and linear regression. It was hypothesized that the decreasing CSS–Q relationships found in the lower Salinas were caused by one or a combination of the following changes in sediment controls over the sample period: decreased wildfire activity, decreased agricultural land area, changes in agricultural composition to less erosive crops, or changes to less erosive irrigation techniques. All data sets were examined for temporal trends in light of the 1967-2011 base period of CSS data, although the irrigation technique data set did not begin until 1993. Factors with statistically insignificant temporal trends and/or trend directions opposing those expected in light of decreasing CSS–Q were eliminated as potential controls. A correlation test was also performed between LOESS residuals and the wildfire burn area metric EBA, as short term responses in basin scale sediment production would be expected from wildfire disturbances. A significant positive correlation between the wildfire and suspended sediment magnitudes would be considered indicative of wildfire as a potential dominant control on decadal scale trends in sediment production, since wildfire has been generally found to increase the production of sediment to a greater degree than water in the steep, brush dominated environments typical of the primary source areas in the Salinas River . Correlation tests were not performed on the agricultural metrics as they were expected to only produce decadal to inter-decadal sediment production responses rather than abrupt shifts in sediment supply dynamics due to the slow rate of change of these factors. As Warrick et al.had found that wildfire affected ~ 100 times more sediment yield from the Arroyo Seco subbasin when followed by a winter of intense storm events, EBA was also examined in concert with peak daily Q for each year. The values of LOESS residuals for years with high EBA values were then compared with consideration given to the peak daily Q experienced by these years, to determine if the convolution of wildfire and subsequent large storms was responsible for temporal patterns of suspended sediment behavior at the annual scale.Beginning in the mid-1960s dry field products like barley and animal feed declined and root products such as sugar beets and potatoes all but disappeared . Intensively irrigated row crops and utilization of land for multiple cropping seasons expanded, including rapid increases in leaf lettuce beginning in the early 1980s, while grape production expanded rapidly from 6–141 km2 between 1971 and 1974, mostly on converted field crop and grazing lands. As a result of these crop changes and the limited use of efficient drip irrigation , groundwater withdrawals are estimated to have increased during the first half of the suspended sediment record . Monterey County, which is mostly contiguous with the Salinas watershed, began recording groundwater withdrawals in 1993 . Between 1993 and 2010 total ground water extraction actually decreased from 0.62 to 0.57 km3 , although irrigated agricultural land area increased from 702 to 732 km2 and total crop area increased from 1270 to 1588 km2 .

These studies include a wide range of process-based crop models as well as empirical papers, published between the late 1990s and 2012, and they vary substantially in the geographic regions examined as well as the extent to which they include on-farm adaptations. In this paper we focus on maize, rice, soy and wheat, four crops that make up a major part of the scientific literature on climate impacts on crops. These crops collectively account for approximately 20% of the value of global agricultural production, 65% of harvested crop area, and just under 50% of calories directly consumed . For these four crops, the database contains 1010 data-points . Of these, 451 are reported as including some form of onfarm, within-crop agronomic adaptation. The majority of these adaptations involve adjusting either planting date , cultivar or both . In total, 28 models are represented in the 56 studies used for the estimation, made up of 17 process-based model families and 11 statistical models. For this analysis we have complemented the existing database in two ways. Firstly, we coded each study based on whether a process-based or empirical approach was used. Secondly we added baseline growing-season temperatures to the database. To do this, each data point was assigned to a country. 86% of points come from studies located in a single country. For the remaining 14% coming from studies with an international scope the assigned country was the country with the highest production of the relevant crop. Average growing season temperatures were calculated using planting and harvest dates from Sacks et al and gridded monthly temperature from the Climate Research Unit . We treat the database of studies as a kind of ‘ensemble of opportunity’ . The benefits of this approach are that predictions from multi-model ensembles have been shown to consistently out-perform individual models in both climate modeling and, increasingly, in agricultural modeling .

Though not derived from a formal ensemble modeling project,growing raspberries in pots the universe of individual studies contained in the database can be thought of as draws from a set of possible models, each of which captures the response of crops to changing climate conditions with some error. The sampling of models is not systematic or random, but instead has emerged from scientific research and associated peer review of work on climate effects on crop yields over the last two decades. The approach described here takes advantage of an implicit weighting derived from representation of models within the scientific literature. To the extent that this representation reflects researchers’ judgements about the best model to use for particular crops in particular locations, it may be that this implicit weighting emerging from the scientific literature is preferred to simpler one-model one-vote aggregation schemes . We use multiple regression to aggregate the results from individual studies to an ensemble average response function. This approach allows us to estimate common response functions at an appropriate level of aggregation. For example, every study in the database examines the effect of change in temperatures on yields, allowing us to estimate separate yield response functions by crop and by baseline temperature, as well as by type of study. Fewer studies examine the effect of CO2 fertilization or adaptation, limiting our ability to model heterogeneity in response to changes in these variables.The effect of adaptation on crop yields is modelled with both an intercept term . This is prompted by the observation that in many studies that report including on-farm agronomic adaptations, adaptation is represented by changing management practices that would improve yields even in the current climate . Failing to include an adaptation intercept in this context will lead to an over-estimation of the potential of the adaptation actions included in these studies to reduce the negative impacts of a warming climate. We therefore include an adaptation intercept in the estimating equation but then subtract it out to produce a damage function that goes through the origin. The true effect of adaptation is captured by the interaction with temperature change, given by the b8 term in equation .

This term reflects the effect of management changes that are not beneficial today but that will be beneficial under a changed climate, the standard definition of adaptation. To estimate the impact of local warming for a prespecified increase in global mean temperature we use pattern-scaling between local and global temperature changes based on the CMIP5 multi-model mean for RCP8.5 . The multi-model mean was calculated using the Climate Explorer tool using methods documented in van Oldenborg et al . For each grid cell we take the change in temperature between a future and baseline period and divide by the mean global warming over this time period. Local warming is greater than global average warming over land areas and is larger at high latitudes and in continental interiors. Gridded local temperature changes are combined with the response functions estimated using equation and baseline growing season temperatures based on CRU and Sacks et al to give projected changes in yield with warming on a 0.5 degree grid. Global average yield changes are calculated by production-weighting the gridded data using production data for the relevant crop in the year 2000 . In presenting results, we focus on global temperature changes ranging from 1 to 3 °C and use 4 cases to examine the importance of different variables. The reference case is based on the temperature response curves for process-based models, including CO2 and adaptation. The ‘No CO2’ case is the same as the reference except without CO2 fertilization. ‘No Adaptation’ is the same as the reference except excluding adaptation. And finally, the ‘Statistical’ case is the same as the reference except the temperature response comes from statistical studies. In order to assess the economic implications of alternative studies of climate impacts on crop yields, we use the Global Trade Analysis Project model . GTAP is a global, computable general equilibrium model which seeks to predict changes in bilateral trade flows, production, consumption, intermediate use and welfare, owing to changes in technology, policies or other exogenous shocks. In this case, we treat the climate-induced yield changes as Hicks-neutral productivity changes. Thus, a 10% yield loss would mean that, if farmers did not alter their practices in the face of the changing climate, application of the same inputs to the same amount of land would result in 10% less output. The economic model does allow for changes in area planted, as well as input intensities, in response to changing relative prices, so actual yields will not change by 10%.

In this sense, all of the economic results reported here allow for economic adaptation . In order to implement the yield shocks under the different climate scenarios, we aggregate the gridded impacts for each of the four crops to the level of the 140 countries/regions in the version 9 GTAP data base . Since maize and soybeans are part of larger crop aggregates in the GTAP data base , the climate-induced yield shocks are diluted by multiplying them by the share of the country-commodity aggregate made up of maize and soybeans, respectively. Thus in a region which does not produce soybeans, the climate shock would be zero, whereas a country in which maize was the only coarse grain produced would experience precisely the productivity shock specified by the aggregated maize results for that geographic region. To be consistent with these incomplete agricultural yield shocks,plant pot with drainage when it comes to reporting the welfare losses, we report the losses as a share of that incomplete production value .Figure 2 shows the temperature response functions estimated from equation . Warming has a negative impact on yields that is worse for maize and wheat than for the more heat-tolerant rice. It is striking that we find very little evidence for any yield benefits from warming over most growing areas—our point estimates are negative even for warming less than 1 °C and even in the 25th percentile of growing season temperatures . This negative impact is generally statistically significant for process based model results at warming above 2 °C. Standard errors for results from statistical models are much larger and bracket zero in almost all cases. The interaction with baseline temperature is in the expected direction: warming is less damaging for crops in cooler locations. Figure S1 shows the gridded yield responses to 2 °C of global average warming for each crop. While many areas see negative impacts, there are some positive effects in the boreal zone and in cooler temperate areas. In figure S2 we show a comparison between our estimated response to a 1 °C warming and the mean of multiple process-based crop models calibrated to specific locations as part of the Agricultural Modeling Inter-comparison and Improvement Project for the three crops that are available: maize , wheat , and rice . The results from these two very different methods are close for both wheat and maize while the findings for rice show more variability. In all cases the AgMIP data are well within the 95% confidence interval produced in this study. Figure 3 shows how the type of study, inclusion of adaptation , and the CO2 fertilization effect affect the climate change response. Point estimates for b3 and b4 suggest that on average results from statistical studies are slightly more optimistic than results from process-based models for small amounts of warming and more pessimistic for higher levels of warming. Error bars for the statistical model are extremely large though, particularly for warming beyond 2 °C, which is perhaps unsurprising given the concentration of empirical results at 1° warming documented in figure 1. The point estimate for the effect of adaptation is in the opposite direction from what would be expected , but the error bars are large and the effect is not distinguishable from zero.

Studies that include adaptation do have more positive yield outcomes than studies that don’t, but those benefits are captured entirely in the adaptation intercept term . Therefore, these findings suggest that most within-crop agronomic adaptation measures represented in process based modeling studies would provide the same benefit under the current climate as they would under future climates. In other words, they are actions that shift the supply curve out to the right but do not change the marginal impacts of future warming, consistent with the ‘adaptation illusion’ identified by Lobell . Finally, the CO2 response functions show statistically-significant benefits of CO2 fertilization that a symptote at 17.3% for C3 crops and 10.6% for C4 crops. Given the functional form assumption, this translates to yield gains of 11.5% and 8.5% for a doubling of CO2 from pre-industrial levels. For C3 crops, this value is close to that obtained from FACE experiments which range between 12 and 14% yield gains for a doubling of CO2 . and therefore this may not be a fully independent validation of the meta-analysis results.Fewer FACE experiments have been performed for C4 crops but available experimental data, as well as theory, suggest C4 crops will benefit less from CO2 except under water-stressed conditions. Figure 4 shows global production-weighted yield losses for a global temperature change of 1 °C–3 °C for four cases. Except for soybeans, the reference case that includes CO2 fertilization and adaptation shows positive effects on yields at low levels of warming, becoming negative between 2 °C–3 °C of warming. Variation between the different cases reflects what might be expected given the response curves shown in figure 3. CO2 fertilization is most important– excluding the CO2 effect produces substantial losses for all crops ranging from 14% to 25% at 3 °C of warming. The effect of excluding adaptation is very small. The effect of statistical as opposed to process-based studies is small and slightly positive for 1 °C–2 °C, becoming slightly negative at 3 °C. At higher levels of temperature change we would expect this effect to become more negative . The 95% confidence intervals are large and mostly bracket zero, with the exception of the No CO2 case at 3 °C of global average warming. Uncertainties are particularly large for soybeans and for the statistical case at 3 °C of warming—both instances where the number of data points in the meta-analysis are limited.

With respect to this aim of separate the role of demand for and supply of labor as drivers of sectoral reallocation, our work is, in fact, mostly related to Lee and Wolpin . Lee and Wolpin devised and structurally estimated a rich model to study the process of labor reallocation from manufacturing to services in the United States. We see our work as complementary to it, to the extent that we are interested in a similar question, but we tackle it from a different perspective. Specifically, our approach aims to impose the minimal structure to interpret the data, closer in spirit to the accounting literature. Relative to the three papers above, we also depart in extending our empirical analysis to as many countries as we could gather data for, rather than focusing only on the United States. Using multiple countries allows us to provide additional ways to identify the size of the mobility frictions, which is an important component of our analysis. More broadly, our work is related to a rich literature that studied the contribution of human capital to growth and development. This literature showed that the level of human capital is significantly correlated with consequent growth , Barro , Mankiw et al.. However, the effects of changes in human capital stocks have been much more elusive and Pritchett. Pritchett in particular, in a famous article, asked: “Where has all the education gone?”. In this respect, our work provides some encouraging answers: we show that growth of human capital stocks matters for explaining reallocation out of agriculture. Methodologically, we are in debt to the approach developed by the growth and developing accounting literature , Barro , Hsieh and Klenow , and more recently Gennaioli et al.. Relative to this literature, we show that observable variation across birth-cohorts can be used in an accounting framework,gallon pot and we introduced a way to measure the role of human capital without having to rely on prices.

In terms of the purely empirical contribution of this paper – that is, documenting novel cross country patterns in reallocation out of agriculture by cohort – our work relates to Kim and Topel , Lee and Wolpin , and Perez , which document sectorial reallocation by cohort but limit their focus to, respectively, South Korea and United States and Argentina; and especially to Hobijn et al. , which, in ongoing work, is also using the IPUMS dataset to document patterns on reallocation across sectors by cohorts, and use them to motivate a model linking demographic forces to structural change. Our model combines elements and insights already presents in Matsuyama , Lucas , and Herrendorf and Schoellman . To the best of our knowledge, we are the first to provide a tractable framework to analytically characterize reallocation within and across-cohorts in a context with general mobility frictions. Hsieh et al. also exploits year and cohort effects to calibrate a model of allocation of talent. It uses them to discipline the relative role, for the aggregate efficiency of the allocation of talent, of changes in frictions that affect human capital investment and frictions that distort the labor market. Relative to this paper, we focus on a simpler framework that allows us to consider fixed-cost-type frictions, which turn out to be crucial to correctly identify the role of human capital. Finally, our work relates to a growing literature that uses longitudinal wage data to reconsider the agricultural productivity gaps and that shows that these gaps are more consistent with sorting across-sectors than with large mobility frictions; , Herrendorf and Schoellman , and Hicks et al.. We contribute to this literature in two ways: we provide a model that highlights when wage data can be informative on frictions; and we show, without relying on wage data, additional evidence corroborating the sorting explanation and casting doubts on the presence of large mobility frictions.We next describe how we use data to quantify the role of human capital in labor reallocation out of agriculture. This is motivated by the results in Proposition 2, which provide an accounting framework to link within- and across-cohorts labor reallocation to the relative contribution of human capital vs. prices/productivity in reallocation out of agriculture. In this Section, we start by documenting a number of novel cross-country facts about reallocation by cohort using micro level data for a large set of countries.

Most of the cross-country evidence available to date only covers aggregate rates of reallocation. Our paper is among the first to provide micro level evidence on the behavior of different cohorts of workers in the process of structural transformation. We present the patterns descriptively to convey information on what the data say in a transparent format, focusing on the novelty of the findings rather than on their role in our approach. In Section 4 we will instead interpret the observed patterns through the lens of theory. There, we make explicit how Proposition 2 can be brought to the data to make inference on whether human capital matters for the movement of workers out of agriculture. Below we introduce the data and measurement approach, and then discuss the novel crosscountry findings on reallocation by cohort.We use micro level data from the Integrated Public Use Microdata Series 8. The data are either censuses or large samples from labor force surveys that are representative of the entire population. We include in our analysis all IPUMS countries for which we have available at least two ten-years apart repeated cross-sections with available information on age, gender, and working industry. This gives us a sample of fifty two countries covering about two thirds of the world population. For fifty one countries, the IPUMS data also include geographical information at the sub-national level which we use in our analysis as a source of additional variation.9 For twenty three countries, we observe four or more cross-sections, for seventeen we observe three or more. On average, we observe countries over a period of 28 years. For some countries, such as United States and Brazil, our data cover a long time span of half a century or more of labor reallocation. Table A.1 in the Appendix lists the countries in our sample, the income level of each country, in 2010, relative to the one of United States, the years of coverage, the agricultural employment shares, and the number of observed cross-sections. The countries in the sample comprise a wide range of income levels, from the United States to Liberia and El Salvador. Eight countries are high-income countries, twenty five are middle-income countries and the remaining nineteen are low-income10. Our sample also spans a large geographical area, covering Asia and Oceania , Africa , Central and South America , and Europe and North America . We focus on males and restrict our attention to those aged 25 to 59. This is meant to capture working age and identify the period after education investment is completed, which allows to consider human capital as constant.

We exclude women from the current analysis given the large cross-country differences in female labor force participation.In the model, we assumed that each cohort has equal size and that size is constant over the life-cycle. In the data, however, we observe that cohorts have different sizes,gallon nursery pot and that the size of a given cohort changes over time due to mortality. We may be concerned that these demographic compositional effects are relevant in explaining the cross-country variation in cohort and year effects. We here perform a series of exercise to show that, reassuringly, demographic composition does not mechanically drive our estimates. First, we compute the year effect weighting each cohort by its share in the population at time t + k rather than at time t. In Figure 8a, we show that this change does not make any difference. Second, we compute the year effect with the raw data – i.e. without smoothing the demographic distribution, which we did in the benchmark exercise to adjust for age-heaping. As is well know, Indian data suffer from extreme age-heaping. Consistent with this, we see in Figure 8b that only in India the year effect estimated with the raw data is different from the benchmark one. Third, we recompute the rate of labor reallocation out of agriculture keeping constant the demographic structure at time t – i.e. we compute LA,t+k weighting each cohort according to !t . Figure 8c, shows that the estimated rate of labor reallocation are almost identical to the benchmark ones. Finally – in Figure 8d – we perform the same exercise, but keeping constant the demographic structure at time t + k. Again, we conclude the demographic changes do not have relevant mechanical effects. In Figure A.3 in the appendix, we recompute the same exercise using sub-national units. We find similar results.This section introduces our empirical approach and discusses how we make use of the data and patterns described above to quantify, in an accounting sense, the relative contribution of human capital and prices/productivity to labor reallocation out of agriculture. Our main starting point is Proposition 2, which tells us that we can do so by leveraging within- and across-cohorts reallocation. Proposition 2 provides a mapping between two observable objects, year and cohort effects, and our two main objects of interest, the contribution of human capital and of prices/productivity to labor reallocation. The mapping, however, is made challenging by the possibility that labor mobility frictions bind, and by general equilibrium. The spirit of our empirical exercise in this section is to exploit – through multiple approaches – observable variation in year and cohort effects both across- and within-countries to discipline the size of the frictions. We then use further micro level data to calibrate the strength of the general equilibrium. We provide a range of estimates depending on parameter values, but the overarching conclusion, which we reach in Section 4.1, is that human capital explains approximately one third of total reallocation out of agriculture. In Section 4.2, we show that, at the same time, human capital has at most a minor role in explaining why some countries have faster reallocation rates than others.Next, we provide estimates for the size of the friction through a series of different exercises. The results of our estimates are summarized in Table 2. Conceptually, we follow two main alternative methods, each tied to a source of variation that can be exploited to back out the size of the frictions. Our first method builds on Proposition 3, which relates the size of labor mobility frictions to the reallocation rates of individuals of different ages. The fixed cost traps in agriculture individuals that would otherwise move to non-agriculture in a frictionless environment. This effect, however, is not symmetric across ages, and is instead stronger for older individuals: they benefit from future increases in non-agriculture wages for fewer years and hence, for given fixed cost, face a stronger constraint. This means that the presence of frictions causes old individuals – the constrained – to reallocate at a slower rate than young individuals – the unconstrained. Fact 3 in Section 3 showed that old and young individuals reallocate at similar rates, thus providing evidence against a sizable role for mobility frictions. The following Lemma shows that this intuition can be used to provide a direct estimate for the size of the frictions.In this section, we provide a proof of concept that it is possible to trigger reallocation out of agriculture through policies that successfully increase the educational attainment of the population. To do so, we identify the causal effect of schooling on labor reallocation out of agriculture in the context of a school construction program in Indonesia. Following the seminal work of Du- flo , we use the INPRES school construction program, which built 61,000 primary schools between 1974 and 1978, to provide quasi-experimental variation in schooling. While the intensity of the program, captured by the number of new schools per pupil, was not random, only somecohorts, those younger than 6 at the time the program started, were fully exposed to the program. Therefore, we can run a fairly standard difference-in-difference exercise: we compare cohorts fully exposed to the treatment to those not exposed to it, in districts with higher or lower treatment intensity.