Well, I have finally figured out the cause of this disease I see almost every year in my garden. It's whitefly. It causes the mottled, blotchy yellowing splotches on the leaves. I should have realized this a LONG time ago, but somehow for all my reading, I never saw the various symptoms all listed together until yesterday. The leaves have that tackiness, too- from the flies' honeydew secretion.
It's worst in the broccoli and green beans. At this point I don't think I will get any broccoli heads at all, and the beans I pick are starting to look poorly too. Other parts of the garden aren't quite so bad- there are some mottled spots on the little cucumber plants, and the thyme. Even if I manage to get rid of all the whitefly, I doubt the plants will recover now. I think I should just go out on a cool night- when they're in a stupor- and uproot all the plants, smother the plot with compost and try again next year (with a different crop in that spot).
My daily morning checks on the plants has had some use, this week. I have got lots of small caterpillars off them. Two days in a row I got several dozen at a time, then only ten or so, this morning only found five. So I have managed to lower their numbers just by hand-picking, and now I have some treats saved up for my fish (saved in tiny jars in the freezer). I was also swiping the underside of the worst-affected leaves with my hand, wiping off some adult whitefly that didn't move away fast enough, and lots of the nymphs and eggs. I'd do this with a bleach wipe but it might harm the suffering plant? or maybe I should try with a paper towel dampened with soap or something. I didn't think this would have much effect, but there do seem to be a few less swarming up this morning...
Going to set beer traps tonight for slugs, too- I think that's what is making ragged holes in the pepper leaves. Last night it rained. Today it will be way too hot to be out there past 10am. Heat index 109º.