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Vegetables
Volume 57 Number 18 Date 08/16/2012 LATE BLIGHT - Weather conditions this month have been favorable for late blight development. Potato fields infected with this disease have to date been confirmed in Adams, Barron, Oneida, Portage and Waushara counties. Continued scouting of potatoes and tomatoes for symptomatic leaves and stems is advised. Organic growers should maintain preventative copper-containing fungicide treatments (approved for organic use) on a five to seven-day schedule. TWO-SPOTTED SPIDER MITE - Home gardeners and fresh market vegetable growers are reporting that mite problems persist at a few locations. Recent rain and cooler temperatures have reduced mite populations, but have not eliminated all existing problems. Mite development is still occurring, just at a slower rate. Monitoring of cucumbers, squash, pumpkins and other vegetables for spider mite is suggested for 1-2 more weeks. POTATO VIRUS Y - The soybean aphid and green peach aphid, both vectors of potato virus Y (PVY), are appearing in northern Wisconsin suction traps. Aphid counts and the risk of virus transmission are considered very low at this time, but growers should not dismiss the possibility of late season problems in peppers, potatoes and tomatoes. Symptoms vary by cultivar, environmental conditions and the strain of PVY. The most distinctive is a wrinkled mosaic pattern on the leaves. Insecticidal controls directed against aphids are futile, but other integrative and preventative measures, such as purchasing seed certified free of PVY, selecting resistant plant varieties, reducing bare soil around plants, planting a barrier crop and planting and top-killing potatoes early, are useful in preventing PVY. --Clarissa Hammond, DATCP Pest Survey Program 
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