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Vegetable IPM Updates Archive
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Whiteflies on Spring Melons (April 18, 2018)
Now that the tax season is over, CPAs can start to relax. But with the spring melon season progressing smoothly, PCAs should start thinking about whiteflies. Overall, whitefly populations are quietly becoming abundant on spring melons. We can easily find adults on melons located at the Yuma Ag Center, and reports from local PCAs suggest that adult populations are beginning to show up on older plantings. As temperatures increase and crops mature, avoidance of excessive feeding from whitefly nymphs should be a primary concern on all melon types. Honeydew and sooty mold contamination on fruit of cantaloupes, mixed melons and watermelons can significantly reduce quality and marketability. Now that whitefly adults are becoming noticeable in a number of locations, PCAs should be diligent in their monitoring and sampling. Our research has shown that to prevent fruit yield and quality losses on spring melons, a foliar insecticide treatment should be applied on threshold; that is, when 2 adult whiteflies per leaf is exceeded when averaged across an entire melon block. At this level of adult abundance, immature populations should just be starting to colonize and timing sprays based on the adult threshold has been shown to significantly reduce the chance of yield / quality loss during harvest. This threshold applies for the use of recommended IGRs (Courier, Knack, Oberon), foliar applied neonicotinoids (Assail, Venom, Scorpion) and Exirel (diamide). For more information, go to these documents on IPM and Whitefly Management: Whitefly Action Thresholds on Spring Melons, and Whitefly Control Options. Also, be aware of honey bees and other pollinators in or around melon fields. If bees are present, be sure to carefully read labels and determine the products bee safety before applying any pesticide in a melon field. If applications are necessary during bloom, try to apply the insecticide that is least toxic to bees, but will still provide adequate control of whitefly adults and nymphs. We also recommend that insecticides only be applied when honey bees are not actively working in the field (e.g. 10:00 pm – 3: 00 am).

Name that insect
Cotton/melon aphid, Aphis gossypii

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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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