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Vegetables
Volume 58 Number 12 Date 07/25/2013 IMPORTED CABBAGEWORM - Defoliation has become more prevalent and pronounced in cole crop plantings since early July. The larger larvae (approx. one inch in length) noted in Grant and La Crosse counties this week are capable of consuming more leaf area, causing larger holes in the leaves and producing more frass (fecal matter). The worms usually 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%, depending on whether the crop is intended for fresh market sale or processing. SQUASH BUG - Reports suggest these difficult-to-control insects are a common problem in pumpkin, squash and melon crops this season. The treatment threshold for squash bugs is based on an average count of one egg mass per plant, although scouting for tiny eggs is often impractical in larger plantings. If the insects are numerous and wilting is observed, pyrethroid insecticides such as permethrin directed against the nymphs are an effective control. Growers should be aware that the efficacy of these materials is reduced at temperatures above 80°F and the smaller nymphs are more readily killed than the adults. Refer to UWEX publication A3422 "Commercial Vegetable Production in Wisconsin" for a list of registered insecticides. -- Krista Hamilton, DATCP Entomologist 
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