That's the dreaded Halloween Plant Disease, I've never seen it before today ;)

But if I were to guess it appears to be 2 species of fungi/mildew growing together. May have started with spider mites but I see no webbing in the pic.

Would need a much closer pic to tell for sure but that looks much more like fungus spores to me - likely Artillery Fungus - than any insects. Are you sure they are moving, living insects? If so then best guess would be some form of mites.

Dave

vgkg types faster than I do ;-)

Good to know, Gardengal. Thank you for the information.

Will cut them back asap. Not quite ready to harvest as we have not had a killing frost/freeze, though it could be any day now.

Thank you.

You don't have to wait for a frost before harvesting. Doesn't really make any difference to the tubers although those that eat them raw claim they are sweeter after a light frost. But they should be fully mature and usable now.

The alternative - and one that probably makes the most sense - is just to cut back the plants now, get rid of the diseased foliage and leave the tubers in the ground until you need them. Apparently they do not store well out of the ground but can last pretty much all winter in the soil. And in z7, there is little concern about soil freezing, so they will remain accessible.

In full disclosure, while I have grown Jerusalem artichokes, it was completely unintentional and with no intent or desire to harvest the tubers. The plant was just sold as a perennial sunflower, which it is. It wasn't until after growing them a season and recognizing how aggressively they spread and how hard they were to control that I realized my mistake :-)) Took me about five years to finally get rid of them......not a plant for an ornamental flower garden!!

Cindy, gardengal is right.....this is sunflower rust in two different stages. Please don't forget the most important part of what she said: you must destroy the plant after cutting it down. Spores will overwinter in the dead plant tissue.

Thank you to both of you.

Will make sure that the foliage does not go into the compost pile.

Thanks again!

Cindy