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Managing Insect Pests During Stand Establishment (August 19, 2015)
It’s that time of the year again. Desert growers have begun planting fall melons, transplanting cabbage and will be direct seeding produce crops in just a few weeks. Accordingly, PCAs and growers will be faced with a number of important insect management issues. As crops begin to emerge, you can expect to encounter a number of insect species that have the potential to cause serious economic losses to crop stands. These include flea beetles, crickets (sometimes grass hoppers), darkling and rove beetles, 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, and feeding by these pests can devour much of the cotyledons or outright kill small plants. If left unprotected, larger seedling plants (1-2 leaf stage) 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 maturity at harvest. Host sources of flea beetle, cricket and "woolly worm" infestations include numerous summer crops (e.g., sudan grass, cotton and alfalfa) and weeds (e.g., purslane). Recently, we’ve observed high numbers of flea beetles and crickets at the Yuma Agricultural Center, and received reports of saltmarsh caterpillars on pima cotton. Experience indicates 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., pyreethroids) or foliar sprays (i.e., methomyl, neonicotinoids) that can cost-effectively minimize their abundance and damage to emerging produce and melon crops. Additionally, seed treatments are available for lettuce and cole crops that will protect stands from flea beetles. 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.

Pale-striped flea beetle

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For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.

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