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Vegetable IPM Updates Archive
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Seedling Pests at Stand Establishment (August 7, 2019)
Desert growers have started planting fall melons and will soon be transplanting/direct seeding produce crops. Accordingly, PCAs will be faced with several important insect management decisions. As crops begin to emerge, they can expect to encounter a number of insect pests that have the potential to cause serious economic losses to crop stands. These seedling pests include flea beetles, crickets, grasshoppers, darkling and rove beetles, earwigs, and saltmarsh caterpillars (‘woolly worms’). These insects all have chewing mouthparts, and most are capable of consuming large amounts of leaf tissue in a short period of time. Seedling crops at the cotyledon stage are most susceptible; these pests can devour entire cotyledons or outright kill small seedlings. If left unprotected, transplants and larger seedling plants can sustain significant feeding damage on the terminal growing points or newly emerged leaves. Not only can this feeding stunt plant growth but can result in lack of stand uniformity and ultimately, maturity at harvest. Host crop sources for flea beetle, cricket and "woolly worm" infestations include numerous summer crops (e.g., Sudan grass, cotton and alfalfa), volunteer melons, and weeds (e.g., purslane). Be especially aware of grasshoppers, as their have many reports in the media lately of migrations occurring throughout the southwest. I have recently seen large numbers on weeds in both the Gila and Dome valleys. Crickets have also been especially numerous this summer, so keep a sharp eye out for these guys. At the Yuma Ag Center, we are also currently noticing flea beetles and crickets on surrounding Sudan grass and weeds. Salt marsh caterpillars have not been reported to date, but are known to disperse from alfalfa and cotton, particularly Pima cotton (non-Bt). Experience suggests that melon fields planted adjacent to these crops/weedy areas are at a high risk from these seedling pests, particularly flea beetles. As summer crops are harvested or terminated during the next several weeks, these seedling pests typically move to the next available host crop; lettuce, cole crops and melons. Fortunately, there are many registered insecticide alternatives available that can be applied via sprinkler chemigation (i.e., pyrethroids) or foliar sprays (i.e., methomyl, neonicotinoids) that can cost-effectively minimize their abundance and damage to emerging produce and melon crops. Additionally, insecticide seed treatments are available for lettuce and broccoli that will protect stands from flea beetles (i.e., NipsIt). For more information on insect pests of leafy vegetables and melons at stand establishment please see Insect Management on Desert Produce and Melons: Pests at Stand Establishment

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                            <strong>Areawide Diamondback Moth Trapping Network</strong>
                        In response to the recent outbreaks of Diamondback moth (DBM), Plutella xylostella in Yuma, we have established a pheromone trap network designed to monitor the activity and movement of adult populations of DBM. PCAs have had difficulty controlling DBM in cabbage, broccoli and cauliflower since October 2016. Traps have been placed in Roll, Wellton, Dome Valley, Gila Valley and Yuma Valley in locations where cole crops are presently being grown or in areas where infestations were known to occur in the fall.
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Remember, When in Doubt . . . . . “SCOUT”

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For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
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