Cucurbit Downy Mildew Update – August 14, 2009

Bob Mulrooney, Extension Plant Pathologist;

The weather continues to be very favorable for downy mildew. It is spreading now to hosts other than cucumber. Cantaloupe, watermelon, winter squash and pumpkin have all been infected in the region. The spots are much smaller on butternut squash and watermelon but still produce the small tuft of fungus growth on the underside of the leaf. All cucurbit growers need to be including a fungicide specific for downy mildew in their spray rotation such as Previcur Flex, Ranman, Presidio, or Tanos at this time. Follow the label directions for plant-back restrictions, mixing partners such as Bravo and mancozeb, and adjuvants. See the 2009 Commercial Vegetable Productions Recommendations for more information.