Pest update from Jon Traunfeld, State Master Gardener Coordinator, UMD
· Upward leaf curling of lower tomato leaves in June and early July was caused primarily by high temperature stress. There is wide variation between cultivars. It is not cause for alarm- the leaves are just protecting themselves from losing excessive water through evaporation. Typically, determinate-type cultivars that are pruned heavily will exhibit significant leaf curling.
· Adults and nymphs of the brown marmorated stink bug (bmsb) are feeding on a large number of fruit and vegetable plants across most of the state. I was in community gardens and public gardens in Washington Co., Montgomery Co., Howard Co., and Anne Arundel Co. last week and observed higher numbers on sunflower, pole bean, and sweet corn, than on pepper or tomato. They seem to prefer tall plants. Feeding on asparagus, broccoli, blackberry, raspberry, peach, apple, buddleia, and hibiscus has also been seen by Master Gardeners.
The insecticide that is now available for commercial growers to use in their orchards- dinotefuran- is not available to home gardeners. Throwing adults and nymphs into a container of soapy water is still the surest organic control method. Organic insecticides- like Pyganic and neem oil- are minimally effective when stink bug populations are high. If you use them try to directly spray nymphs. There is insufficient “real life” information on traps for us to make recommendations on their effectiveness.
· Interesting research by Jerry Brust, UME Extension Entomologist and Karen Rane, Director of UME’s Plant Diagnostic Lab on transmission of a pathogen through bmsb feeding: https://www.agnr.umd.edu/Extension/agriculture/mdvegetables/files/yeast%20transmission%20by%20BMSB%20in%20vegetables.pdf
· Good web pages for diagnosing fruit problems in tomato and other vegetable crops: https://mdvegetables.umd.edu/images/Physiological%20Disorders%20of%20Tomato%20Fruit.pdf; https://plantdiagnostics.umd.edu/level2.cfm?categoryID=61.
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