I came home from work today to an issue I've not seen before. This is only my second year gardening and last year's squash plants did well. This year a new bed was created with new soil. Overnight the leaves on one of my zucchini plants have turned brownish, a little mottled and have curled edges. The other zucchini plant behind it is fine and the Heirlook straightneck squash plant to the left is fine. Cucumbers climbing behind are fine although they are ballooning out at the bottom due to the heavy rains.
I've seen some aphids, but not many. A few squash bugs - not out of the norm. We have had significant rain lately - but today's thunderstorm was about 20 minutes. Does anyone have any ideas? pH is 6.8