What is causing this effect on my butternut squash?
Hi there. I can't identify what is happening on the foliage of my butternut squash. In the first pic, there is a distinct dimpling and discoloration on the leaves. These are leaves on the lower part of the plant. Over the past few weeks the lower leaves have slowly yellowed, at which point I would remove them. The second pic shows the plant's newest growth before it started running. Although only 1 flower has opened, all buds look very healthy.
I started spraying with a Safer (I think) combination fungicide/insecticide and have done so every week for the past 3 weeks.
I've had squash vine borers but see no evidence of frass, etc. None of my other squashes look this way. I'll appreciate your help in figuring this out. Maureen