It's that time of the year when it seems like everything is a possible target for mildew and fungus.
These poor squash plants went from a touch of white on the lower, oldest leaves to completely coated seemingly overnight. The culprit here is powdery mildew, which is the bane of the entire cucurbit family (squash, cucumber, melon) late in the season.
These plants will be chopped out as soon as possible. Although they would happily continue producing fruit (at a reduced yield), it is better to get the infected plants out of the area. It is always tempting to try to squeeze every last bit of productivity out of each planting (especially after working so hard to establish it), but it's important to consider the bigger picture: later plantings are still coming into production now so there's no shortage, and free spaces allow for better establishment of cover crops which will benefit fertility in future years.
I've added a few new tools to my management plan this year, but no matter what I do it really just seems to delay the inevitable. Pulling out mildew-y older plants just seems like a part of the late summer rhythm.