Cucumber leaf disease

Can anyone help me finding the problem for my cucumber leaves? Is it because of Powdery mildew? I tried spraying with nim oil and dish cleaner shop but not much improvement. Any idea how to get rid of this will be very helpful. The temperature here is 95F+.

Hi Abdullah, welcome to Permies.

Looking at the pictures provided, I can't say for 100% sure what is happening, but I believe there are a couple things going on. Powdery mildew and/or downy mildew (the first picture), bacterial wilt (the crispy brown leaves in the second and third pictures), and possibly some evidence of pests like squash bugs or cucumber beetles.

In my experience, leaves that show symptoms of disease won't heal and look normal again. The sick looking leaves are a loss and the hope is to prevent the spread onto new healthy green leaves and other plants.

Do you see any of these guys on your cucumber plants?

I see the cucumber beetles the 3rd one in your picture.
I am using glue trap to catch the beetles.

Should i remove all the affected leaves? There will be very few leaves then. Any other suggestions to protect future/non affected leaves?

May I suggest keeping an eye on those glue traps as they can accidentally trap beneficial insects that prey upon and eat pests. If there's other bugs like assassin bugs, green lacewings, and lady bugs stuck on the glue traps, and not many cucumber beetles or other bad bugs, they may be doing more harm than good. Here's a neat picture of an assassin bug feasting on a cucumber beetle.



I think there's a couple options to consider for protecting future growth. So the diseased and dead leaves are no longer being a benefit to the plant, harnessing sunlight and making sugars, and are harboring disease spores and possibly other things like cucumber beetle eggs for example. Removing all the sick leaves won't do any more harm than what the diseases and pests have done. Those leaves that are removed really need to be either burned or bagged and taken off site, far away from the garden. You mentioned you have neem oil, and neem can be a great preventative treatment in certain situations, and I think it's worth a try and hope to get good healthy leaves and get some cucumbers to eat.

Attach are from my bottle gourd plant. Do you think it is same reason?

I'm not quite sure if the gourds are suffering from the same maladies. Those pictures look like it could be a mosaic virus or possibly a nutrient deficiency.

Thanks james for your suggestions and help.

You're welcome Abdullah, glad I could help.