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Vegetables
Volume 58 Number 5 Date 05/30/2013 ONION MAGGOT - Emergence of first generation flies continued at south-central and southwestern locations. Peak emergence is anticipated in the Eau Claire, Hancock and Wausau areas next week, following the accumulation of 680 degree days (base 40°F). Flies of this spring generation are usually the most abundant and damaging, especially at sites where onions are grown in succession. Preventative soil insecticides should be considered if maggot damage to the last year's crop exceeded 5-10%. Home gardeners are advised to rotate this year's plantings as far as possible from last year's to reduce the likelihood of damage. SPOTTED CUCUMBER BEETLE - This distinctive yellowish-green beetle with black spots is appearing in alfalfa in the southern half of the state. Similar to the cabbage looper, the spotted cucumber beetle does not overwinter in Wisconsin but migrates in from southern states each year, arriving around June. Both this species and the striped cucumber beetle are efficient vectors of bacterial wilt of cucumbers, muskmelons and watermelons. Early beetle control may be required in large commercial muskmelon or cucumber operations in June. The first symptom of bacterial wilt on cucumber and melon is a distinct flagging of lateral and individual leaves. -- Krista Hamilton, DATCP Entomologist 
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