Apparently we've been hit with "late blight." (Don't worry -- the wilted swiss chard is just the standard mid-day reaction to hot weather, not some sort of disease.)
The cool, wet weather we had this spring was a factor in its catastrophic spread.
The only tomato that did not get the blight was a "Matt's Wild Cherry." I had grown this variety years ago, and it hadn't done all that well. As the catalog says, it doesn't yield many tomatoes for the amount of space it takes, and I'd grown fond of the grape tomato varieties that are available now, so I'd stopped growing the wild cherry in favor of the grapes.
This winter, I decided to get rid of seeds I never use, and I had a few of the wild cherry seeds, so, on a whim, I started them indoors. One sprouted, and it went into the garden. Apparently, it has innate resistance to late blight, because it's surrounded by dead plants, and there isn't a single spot on it.
