My cucumbers have a grayish groups on the very lower(oldest) leaves about a 1/2 in. or less in size. Is this the beginning of powdery mildew ? If so , how can I stop it ? I'm worried about the rest of my plants ! Is this treatable ? It doesn't rub off when I rub it. Need your advice....
Is This Powdery Mildew ?
I t sure sound like powdery mildew, although ther are other diseases with similar symptoms. Ther are lots of treatment for mildew, but all involve creating a basic environment on the plant. It thrives in acidic conditions like acid rain. Baking soda works for me ( small box of Arm and Hammer in ten quarts of water). There are several companies selling Sodium bicarbonate formulations to commercial growers, Many of the organic folks use milk formulations ( either powder or regular). Copper sulphate based fungicides also work.
Thank You Farmerdill. Never had this problem before. Will take your advice. I have, in my shed, a copper spray from "Gardens Alive." Will that be good for this and also will this spread to the rest of my veggies? Should I spray everything as a safety precaution ?
Normally powdery mildew is limited to squash , pumpkins, cucumbers and cantaloupes. The copper fungicides are good for a lot of other fungal diseases including foliar diseases of tomatoes.
Try http://hgic.clemson.edu/factsheets/HGIC2206.htm for a better description of cucurbit diseases.
Farmerdill -- Should I spray my tomatoes & strawberries ? Just in case ?
Most of us have foliar diseases on our tomatoes so we start spraying with either copper or Daconil beginning at transplant as a preventive measure. Never had a problem with strawberries so never sprayed them.