Deer mice typically have a small home range , so if the target species for your control program is the deer mouse only, you should use a 98-foot spacing. This ensures that any deer mouse will have access to at least one bait station within its home range. Roof rats have a larger home range , so the 164-foot spacing will put at least one bait station in each rat’s home range while reducing the total number of bait stations required to effectively treat the orchard. If both roof rats and deer mice are present, use the 98-foot spacing.These formulas will calculate the number of bait stations required for the orchard and also provide an approximate location for each bait station. Note, however, that the actual spacing between individual trees and rows of trees will dictate the ultimate placement of each bait station, which will in some cases be in the tree that is closest to the calculated location. Use bungee cords or wire to attach to bait stations to tree branches. Bungee cord takes less time than wire; wire is cheaper, but it is also harder to use and must be frequently replaced. Nylon cable ties were not effective for keeping bait stations securely attached to branches. To prevent spillage, bait stations should only be attached to branches that are at an angle of 45° or less from the main trunk. Bait stations can be attached to the top or the underside of the branch, square pot but must be rotated so the hole in each end cap is at the top . An initial amount of one cup of bait should be added to each bait station. Check the bait stations on a regular basis to ensure a constant supply of bait; you can adjust the amount of bait you put in each station according to uptake. If necessary, you can put as much as 1 pound of bait per station at one time.
It is important to note that diphacinone is a first-generation anticoagulant that requires multiple feedings to give the target species a toxic dose. As such, it is essential that you maintain a constant supply of bait in the stations throughout the duration of the baiting process. You can deploy bait stations without bait for a few days at first to allow rodents to become acclimatized. After this initial period, keep replenishing the bait for around 4 weeks or until consumption stops. After cessation of a baiting program, you can keep the bait stations in place, but filled with non-toxic oats, in order to assess re-invasion by nearby roof rats or deer mice. If you do see evidence of re-invasion, you can continue baiting until the start of the growing season.Bait stations may also be deployed at ground level, but previous studies have found that elevated baits are more effective against roof rats than bait placed at ground level . Additionally, bait stations placed at ground level increase the likelihood that non-target animals will fall prey to the bait. Re-invasion rates can be high for many rodent species, with immigration occurring as soon as two months after control if adjacent areas are home to large populations . As such, it is important to consider rat and mouse outbreaks and invasions at a broader, landscape level. Coordinated control programs implemented by neighboring landowners should provide the best results against damaging rat and mouse populations.In wet and humid conditions, the bait can absorb moisture. If this occurs, replace it with fresh, dry bait to maintain efficacy. Bait stations were designed to minimize spillage of bait during rodent feeding, but you still need to monitor for bait spillage and immediately clean up any spilled bait.
Deer mice have been known to nest in bait stations. Deer mice are known reservoirs of the Sin Nombre virus, which causes the potentially fatal Hantavirus Pulmonary Syndrome . This virus is transmitted through the inhalation or ingestion of aerosolized saliva, feces, or urine of deer mice. Because of this, it is important to make sure that any wind is behind the bait application technician when he or she opens the bait stations, so that any aerosolized particles will be carried away, downwind. Although concerns of secondary toxicity are typically quite low with first-generation anticoagulants , they still hold some inherent risk. As such, the survey of pest carcasses is always an important part of implementing a baiting program using anticoagulants. During a baiting program, most rodents die below ground but a few will be found above ground. Check for above ground pest carcasses once or twice a day. Remove the dead rodents and dispose of them by burying or burning . Alternatively, you can wrap carcasses in newspaper or double-bag them and dispose of them in the trash. Latex or nitrile gloves should be worn when handling dead rodents to prevent potential infection from the various diseases or parasites they may carry. Initial start-up costs for an effective baiting program will vary depending on which pest species are present, since deer mice require more bait stations per acre than roof rats alone. At the time of this writing, the individual bait stations cost $4.72 each, and 1 pound of the 0.005% diphacinone oat bait cost $1.75. Estimated start-up costs, then, using the 164-foot spacing, would be approximately $624.07 per 80-acre orchard . Initial costs for deer mouse management would cost considerably more: $1,794.17 per 80-acre orchard . These estimates are based on initial placement of one cup of bait per bait station. If rates of infestation are high, you may need to place additional bait. Also, these estimates do not include tie-up or labor costs, which will vary considerably depending on the tying method you use to fasten bait stations to tree branches.
It is important to note that subsequent costs for bait programs go down dramatically, since the initial cost of bait stations accounts for the bulk of the expense of a start-up baiting program. The bait stations described are very durable and can be used across multiple fields and multiple years, further reducing the long-term cost of baiting programs. Ultimately, we believe this baiting strategy will allow for effective, economical management of roof rats and deer mice in nut and tree fruit orchards in most areas where these species are found. This approach also substantially reduces the potential for negative impacts from rodenticide bait on non-target species, thereby minimizing the hazard to the natural environment.There is strong evidence that the majority of wild and cultivated plant species benefit from or rely entirely on the transportation of pollen grains by bees, other insects, birds and mammals . Furthermore, at the within-plant or whole plant scales, many crops exhibit decreased crop production in response to decreases in the number and types of pollinator , and these results have been extrapolated to field and landscape scales , as well as regional and global scales . In natural populations, pollination may also strongly limit reproduction, particularly in fragmented landscapes . While pollination clearly affects reproductive yields of many wild and crop plants , the degree to which it regulates yield in real-world cropping systems is debated . The emphasis on the role of pollination in determining yield has been criticised on the basis that it does not account for possible post-pollination processes affecting the amount and quality of fruit maturation . For example, water and nutrient limitation can strongly affect early fruit abortion and variation in losses to pests and diseases may ultimately be more important than pollination in determining realized yields . Furthermore, the interactions between pollination and post-pollination processes are rarely considered for wild plants and are almost unstudied in crop plants . Given widespread concerns about colony losses of Apis mellifera L., a major crop pollinator worldwide , as well as evidence for declines of other pollinators at landscape and regional scales , a greater understanding of the importance of pollination processes for reproduction and yield is critically needed. To date, studies of pollination limitation in tree crops have examined only a subset of flowers per plant or invokepollinator limitation without supplementary hand-cross pollination of the flowers . Instead, square plastic planter yields should be analysed at the whole plant scale to avoid the confounding effects of resource allocation among individual flowers or branches . Thus, experiments are needed that compare hand-pollinated yields to those in which pollinators are totally excluded , with and without resource applications. Furthermore, high fruit yield may come at the expense of the trees’ vegetative performance, such as quantity of foliage. The indirect influences of pollination in combination with plant resource variation on vegetative features of crops such as leaf quality and quantity is not yet investigated. Commercial almond production is an excellent model system for testing effects of pollination on crop production and foliage variables in different water and nutrient applications because results are likely to be applicable to many fruiting trees, such as apples, cherries, pears, peaches and plums, all with main varieties depending on insect pollination. Almond trees are generally considered to be drought-tolerant , but growers are highly dependent on irrigation and nutrient inputs to produce high yields of top quality . Moreover, almond production in California is highly dependent on honeybee management to set a commercial crop, but declines in honeybee colonies and an increase in production acreage have resulted in honeybees becoming a limiting resource for almond in the USA .
Furthermore, California, as one of the largest irrigated agricultural areas in the world, is facing water shortages, and almond growers may be forced to reduce their annual water use . Almond was therefore selected to test experimentally the effect of pollination on fruit yield and foliage while taking into account the interactions of pollination, water and nutrient applications in a full-factorial design.Almond [Prunus dulcis D.A. Webb] is a subtropical obligate outcrossing tree that is intensively grown in large monocultures in California, where the climate is similar to its place of origin in the Middle East . Almond flowers must be pollinated by a compatible variety to produce a fruit . Bees, and possibly other insects, are the principal vectors for transferring the sticky pollen between flowers of different varieties, and there is little to no transfer by wind . The mature fruit consists of one or occasionally two kernels per fruit, surrounded by a shell nested inside a hull. The most popular variety for nut production in the USA is Nonpareil, which comprises around one-third of all marketable nuts produced in California . Compatible pollen donor varieties for Nonpareil include Padre, Mission, Wood Colony and Carrion. Almond trees flower from early February to mid-March in California, and fruits ripen from July to September, depending on variety, weather and age of the trees.The experiment was carried out from January to August 2008. The site was located in the Sacramento Valley, the northern portion of California’s agriculturally intensive Central Valley, in Colusa County, near the border with Yolo County . Colusa County produces around 5% of California’s marketable almonds. Precipitation in this area is low, with an annual amount of 268.7 mm . Rainfall occurs primarily from October through May, with a peak in January; no precipitation typically occurs from June to September. We selected young, productive trees for this experiment, because kernel quantity and quality of the whole tree can be measured, and accumulated resources are limited in smaller trees . The 3.2-ha study site consisted of Nonpareil trees that were grafted onto peach rootstock [Prunus persica Batsch] in 2005 and were planted in 2006 . The trees were approximately 1.75-m tall and had not been harvested prior to this study. The trees were planted 4-m apart within rows and 6.4 m between rows. Several ‘polleniser’ varieties compatible with Nonpareil were available in surrounding orchards located 100–300 m away from the experimental trees. These included a 16-year-old, 4.7- ha orchard with Mission and Carrion varieties and a 13-yearold orchard with Nonpareil and Wood Colony. The eight hives closest to the experimental trees were 300–350 m away and were part of the commercial pollination management system used by the grower. Padre pollen was placed every second day at 10:00 and 14:00 h at the nest entrance of the honeybee hives to maximise the amount of compatible pollen transported by honeybee workers to Nonpareil trees.