Large farms may benefit by blocking major gopher access routes with any available solid material, but I don’t believe there is a viable material that will completely head off an infestation.Although not appropriate for all operations, flood irrigation can be extremely effective not only at killing gophers under the water but also at driving the survivors to field edges where they can be trapped. Flooding burrows with a hose can sometimes be effective in a small operation, providing that it is done at a fresh burrow. Gas cartridges with sulfur and sodium nitrate as active ingredients are still allowed by organic certifiers and can be effective if used on new burrows . They cost $1–$2 per cartridge and have an approximately fifty percent success rate. After inserting a gas cartridge in a burrow, be sure to cover the opening to prevent the gas from escaping. One company sells a blower that is supposed to move the gas beyond blocks in the tunnel system. I feel this may dilute the strength of the gas, although no scientific evidence yet exists to validate this idea. The “Rodenator Pro” is a device that injects a mixture of propane gas and oxygen into a gopher burrow and then ignites it with a spark, destroying the tunnel system. I recommend occasional use of the Rodenator in vineyards and orchards to remove permanent tunnels that run along perennial crop rows. It’s not appropriate for annual vegetable operations as it can damage crops and is unwieldy in row crop settings. Some growers use trapping as a main strategy and the Rodenator for areas where gophers and ground squirrels have settled. After poison baits, round plastic plant pot which are no longer allowed under organic certification rules, trapping is the most effective way to control gophers.
The best sites for setting traps are where there has been recent activity, marked by fresh mounds of moist, dark soil in the morning or by holes that have been recently plugged. Three trap designs currently dominate the market. The most common in California is the Macabee trap, invented by Zephyr Macabee in 1900 to protect his Santa Clara Valley almond orchards. The Macabee is a “pincher” type trap that impales two wires in the body of the gopher when it bumps into a trigger. The usual set for these traps is to locate and dig down to the main, larger burrow and insert two traps facing away from each other, connected by a wire. After the set is completely buried the wire is left on the surface and flagged to help find the traps. There are different opinions about letting light and air into the tunnel where the trap is located. Some say light and air will encourage the gopher to pack the trap area with soil and not set the trap off, and some say it is the light that draws the gopher to the trap. I’ve found that both methods work and that adding some vegetative bait helps as well. I’ve seen some modifications where the Macabee trap is inserted into a section of two-inch ABS drain pipe about eight inches long, either left open or closed at one end . This addition seems to help catch the gopher even if it is pushing soil ahead of it. Another older, standard trap design that is still popular is the box trap. This small wooden box is open on the bottom and at one end, and houses a trigger and metal “choker” loop or cable that grabs the gopher as it enters. A more modern version called the “Black Hole” is made of plastic tubing and a cable choker. These traps work by fooling the gopher into thinking it is still in the tunnel. The gopher is lured to the end of the trap where a small opening allows light and air in and the gopher gets caught trying to close the opening.
Box traps are also placed in the main tunnel in pairs, although I’ve seen a single trap work when placed in the mound’s entrance tunnel. Although both Macabee and box-type traps are effective, I’ve had the most success using the Cinch trap from Oregon. This is also an older trap that for many years was used only by professionals and can be slightly hazardous and difficult to set due to its double trigger and strong spring. Like the box or Macabee traps, Cinch traps can be used in pairs, but can be set more quickly and can be even more effective than the other trap types when placed singly in the burrow entrance. The method I use is to open the burrow at the freshest mound and insert the round, extended jaws of the trap into the burrow entrance. I use a stake that is sized to open the burrow as wide as the trap’s jaws and then use the same stake to mark the trapping site. The gopher is caught when it comes to the surface to close the opening in the mound.Pawpaw is the only member of the neotropical family Annonaceae that is native to North America with wild populations found in forested lowland areas in Canada and the eastern United States, as well as the southern and midwestern United States. This fruit tree is considered a vulnerable or even an endangered species in several regions, including in New York state. Pawpaw trees have a pyramidal growth habit and may reach up to 10 m in height. They have a suckering habit with numerous saplings often surrounding adult trees. Individual trunks live for approximately 40 years, but the root system can continue to generate new growth. Clonal saplings, also known as root suckers, originate from the root systems of mature trees.
Pawpaw flowers are protogynous, and cross pollination from a genetically distinct tree, with a few cultivar exceptions is required to produce genetically heterogeneous seedlings arising from dropped seeds. Pawpaw fruits are the largest edible fruit indigenous to North America. Blossoms emerge in May and have a pungent scent that is attractive to detritivore insects, including flies and beetles. The pawpaw flower has one to nine ovaries with each fertilized ovary gives rise to a large, many-seeded berry, fruit. Pawpaw fruits have a thin, pale green skin, and are borne singly or in clusters. The fruit is ripe between mid-September and October, depending on the growing site and the genotype. Ripe fruits possess a soft pulp that maybe smooth, grainy, or gelatinous. Pawpaw trees reach their maximum fruit production after approximately seven years. In several regions of the United States, there is an increased interest in pawpaw cultivation. For example, several groups of Indigenous Peoples in the territories surrounding the Great Lakes Region, including members of the Haudenosaunee Confederacy, are planting pawpaw as a traditional food crop. An experimental orchard of pawpaw cultivars and advanced open-pollinated breeding lines was established at Cornell University in 1999. Virus-like symptoms consisting of tree stunting or foliar mosaic, patchy discolorations, chlorosis, mottling, and distortions were observed early on in some trees. In contrast, leaves of asymptomatic trees were uniformly dark green in color. Virus-like symptoms were apparent on trees and saplings, eventually suggesting the occurrence of a soil-borne agent. Symptoms were rarely present throughout an entire tree; instead, they were noticed along several adjacent branches with leaves on top of the scaffold of symptomatic trees often remaining asymptomatic, suggesting that some trees may have recovered from symptoms. Based on these observations, symptoms were assumed to be of virus origin. In this study, we hypothesized that one or several viruses, perhaps soil-borne viruses for which plant recovery from symptoms is known, are present in symptomatic pawpaw trees. We used high-throughput sequencing to characterize the virome of pawpaw trees. The HTS results were validated by RT-PCR in combination with Sanger sequencing and by serological assays.An experimental orchard of pawpaw cultivars and advanced open-pollinated breeding lines established at Cornell University in Lansing, New York in 1999 was selected for this study. Most trees and saplings exhibited virus-like symptoms in the experimental orchard. Prominent symptoms were tree stunting , leaf distortions, mosaic, vein clearing, patchy chlorosis, extended chlorosis, and mottling . Symptoms were often unevenly distributed in the tree canopy with asymptomatic leaves on some branches and in the upper tree scaffold. Monitoring pawpaw trees for virus-like symptoms in May 2022 revealed that 89% of them were symptomatic. Trees from the 10 commercial pawpaw cultivars and 18 advanced open-pollinated seedling lines were symptomatic, 25 liter round pot suggesting no association between virus-like symptom presence and pawpaw genotype. Similar symptoms were apparent on trees and saplings surrounding the symptomatic trees with most saplings underneath symptomatic trees being symptomatic . A few asymptomatic trees were identified. These were spatially located at the edge of the experimental orchard at the south end of rows 2 and 3 , and north end of rows 1, 3, and 4 .
Saplings beneath the asymptomatic trees were predominantly asymptomatic.We identified and characterized TRSV and ToRSV by HTS in pawpaw trees exhibiting stunting and/or foliar patchy discolorations, chlorosis, mottling, vein clearing, and distortions in an experimental orchard at Cornell University. The presence of TRSV and ToRSV was validated in the trees from which nucleic acids were isolated for HTS and in additional trees from the same experimental orchard by RT-PCR and DAS-ELISA. Although we did not attempt to demonstrate causality, it is reasonable to presume that TRSV in single infection or TRSV and ToRSV in dual infections are responsible for the symptoms observed in theexperimental pawpaw orchard at Cornell University, given the high association between the occurrence of one or both viruses and disease symptoms in the pawpaw trees tested, as well as the history of the pawpaw trees. Additionally, TRSV was found by RT-PCR and DAS-ELISA in symptomatic pawpaw trees in a commercial orchard in Maryland. TRSV and ToRSV are both transmitted non-persistently by ectoparasitic dagger nematode vectors of the Xiphinema americanum group. The almost even distribution of symptomatic trees throughout the experimental orchard at Cornell University, except at the edge at the north and south sides although some of these trees were infected with TRSV, suggested that most of the trees were likely infected with TRSV when the orchard was established. If X. americanum nematodes would be involved in the spatiotemporal distribution of this virus in the experimental orchard, patchy aggregations of symptomatic trees would be expected. This was not the case because the distribution of symptomatic trees was non-clustered. In addition, the fact that some of the asymptomatic trees were infected with TRSV suggested that the planting material rather than dagger nematode vector-mediated virus transmissions likely explains the widespread distribution of TRSV in the experimental orchard. Nonetheless, we cannot rule out the presence of X. americanum in the experimental orchard and their involvement in short distance spread of TRSV or even ToRSV. Soil samples would need to be collected at various sites and tested for X. americanum to ascertain the occurrence of this nematode vector in the experimental pawpaw orchard. Validating efforts of HTS results revealed TRSV in every leaf sample tested from symptomatic and asymptomatic trees in the experimental pawpaw orchard at Cornell University . This finding supports the idea that trees were likely infected with TRSV when the orchard was established. It is possible that the TRSV infection was latent initially, and disease symptoms became progressively apparent after the orchard was established. Viruses switching from latency to a disease symptom-causing state are occasionally observed in infected perennial crops due to various factors including environmental stimuli, developmental growth stage, and mixed virus infections. Additionally, it can be speculated that, given TRSV is pollen and seed transmitted in several crops such as soybean and Pelargonium hybrids among others, the pawpaw seedlings used as rootstock for producing the experimental trees were initially infected. The fact that TRSV was identified in different grafted pawpaw cultivars in distant orchards in New York and Maryland adds credence to the rootstock seedling origin of the virus. Similarly, the detection of TRSV in flowers collected in May 2022 from infected trees in the experimental orchard in New York, and in fruitlets sampled in the commercial orchard in Maryland in June 2022, adds plausibility to the virus transmissibility via pollen and/or seed in pawpaw; however, these hypotheses need to be experimentally tested for validation. The detection of ToRSV was sporadic in the experimental orchard at Cornell University, suggesting its possible presence in some but not all the propagation material used to produce the pawpaw trees.