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Vegetables
Volume 58 Number 12 Date 07/24/2014 LATE BLIGHT - Late blight was confirmed for the first time this season in a Portage County potato field on July 18. Based on expected rainfall and potential for spore dispersal, UW Plant Pathologist, Dr. Amanda Gevens is recommending that growers of potatoes and tomatoes in the Portage County area begin treating their crops with effective fungicides (anti-sporulants) on a five- to seven-day spray interval as a protective measure. A seven-day program is appropriate for other Wisconsin potato production areas. Scouting efforts should also be intensified, concentrating on field corners and areas sheltered by trees, where late blight symptoms generally first appear. Registered fungicides for potato late blight in Wisconsin are listed at the UW-Madison Vegetable Pathology website. IMPORTED CABBAGEWORM - Defoliation has become more pronounced in cole crop plantings since early July. The late-instar larvae (>1 inch long) noted in Dane, La Crosse and Vernon counties this week are capable of consuming more leaf area, causing larger holes in the leaves and producing more frass. The worms can be found on leaf undersides and inside the developing heads or growing points of plants. Treatment thresholds for this pest range from 10-75% of plants infested, depending on whether the crop is intended for fresh market sale or processing. STRIPED CUCUMBER BEETLE - Adults have been increasingly active over the southern half of the state in the last two weeks. Growers of cucurbits should continue to monitor plants for these yellow and black striped beetles that transmit bacterial wilt of cucurbits, infecting cucumbers, melons and squash through feces or contaminated mouthparts. Control is warranted for populations of 4-5 beetles per 50 plants. FLEA BEETLES - Reports indicate that flea beetles have been a persistent problem for home gardeners this season. In many instances their damage is aesthetic, but control may be considered for young plants if beetles are present on every plant and defoliation exceeds 30%. -- Krista Hamilton, DATCP Entomologist 
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