Does this look like powdery mildew? If not, any ideas on what it is? Should I just cut off the infected leaves and see if it spreads? Or should I pull the plants BEFORE it spreads? These are lemon cucumbers.
It's powdery mildew. Cut off the worst affected leaves and do a search here for fungicides to use. Once you've got it you can only control it. Preventative spraying is the key.
Thanks! I've just read milk and water or baking soda and water. I'll do some more research. They are about 3 feet away from my other cuke plants which look fine. Should I just pull the infected ones? From what I read it sounds like the spores are probably all over now so should I start preventative on the uninfected ones? By the way, when it's said preventative, do gardeners treat before there are signs of it just because they know it's a possibility?
No need to pull the entire plant out unless it's severely covered with PM, and it doesn't look that way in the photo. Just cut the worst leaves. Yes, spray all your plants. And yes, that's what I meant by preventative. If you know you have a history with PM then it's essential that you start spraying before it shows up (this is an important thing to note for next year).
I spray before hand because it is almost a guarantee that cucurbits will get PM so as a preventative, to hopefully avoid it, I spray with 20% whole raw milk and the rest water when they are seedlings (about 4 weeks old) and then after they are planted and again every two weeks or after it rains. Some people also use baking soda and others use potassium bicarbonate which is similar to baking soda. Raw milk works best for me. If only a few leaves have it, I snip them and spray the others. The only problem with snipping is that you can only snip so many leaves and then your fruit risks scald. Whether you decide to keep the infected one or not, I would definitely spray all cucumber plants that don't appear to be infected. Spray entire plant, tops and bottoms. If you have squash, pumpkins and melons, I'd spray them too. Good luck and hope you can maintain your plants and get lots of cukes!
Thanks! I will add spraying to the routine starting today. Glad to hear they aren't lost ;)