The whiteish dusty powdery stuff might be Powdery Mildew but the yellowing of the leaves, chlorosis, probably is from another source. Sometimes just washing the plants leaves can help eliminate the Powdery Mildew while other times using something like a 50/50 mixture of fat free milk and water or mixing 1 teaspoon of Baking Soda in 1 quart of water and spraying that on the leaves will help. The chlorosis is another problem and requires a close look at the whys to determine how to correct for it. There are many reasons a plants leaves loose the chlorophyll they need. Here is a link that might be useful: plant chlorosis

Thanks, Peter and Ig. The PM is already spreading to the acorn and butternut. I soaker hose long-watered yesterday and I pulled the gray, dead PM leaves off and put them into the trash bin. Someone I met suggested fish emulsion feed. Of course, I cannot now locate that small green bottle of stinky liquid. The soil drains well. Weedy area and some Heritage raspberries or maybe they are wild blackberries are sprouting up here and there. It's a constant challenge. I'm tempted to experiment on the two front zucchini plants: immunox on one and "copper spray" on another. (What sort of copper spray? Any drawbacks?). The butternut squash up hill at my neighbor's isn't particularly full, but doesn't have any noticeable PW either. It rained last night and this morning, so that should help. With no rain or moisture, how could any Epsoma or 10-10-10 break down to get to the plants? Question: if overhead watering contributes to Powdery Mildew, PM, then what about rainfall? Is rainfall any different than overhead watering (assuming minimal back spash of soil onto leaves)?

I doubt you have much of a concern. Powdery mildew is quite different from other fungal problems in that it is entirely climate/culture related. It also needs living plant material to survive - no living plant parts = no concerns for spores wintering over. That's why inground plants subject to powdery mildew seldom develop it until later in the season when the conditions are right. Make sure you have proper air circulation and sufficient light and you should be fine. btw, Verbena bonariensis will self seed very easily all on its own.....to the point where it is a borderline invasive in many areas. Just allow the seeds to fall or scatter wherever you want this plant in your garden and you will have it forever!!

I am looking at the photo from May 16th (I didn't notice it before) and that looks like some bugs. And you say they came back. Can't tell for sure what they are, but they look like scale. I am surprised, have not seen scale on jades yet (maybe just my luck?) and I have grown many of them over the years. Anyway, test if scale: take a q-tip or cotton ball or even soft tissue or rag. Moisten in rubbing alcohol and wipe over the 'thing'. Do not 'push' hard; if scale, it will die on contact and comes off very easily. Scale is quite regular in shape, circle or oval, just slightly raised in the center. Google photos of scale and you'll see how they look. They do not move, rather stay in same spot. Almost as they are glued to the plant. You could scrape scale off easily with your fingernails...I prefer the wiping. Don't like dead bugs under my fingernails, lol. If you try that, it also should come off easily. If you have to scrape hard to the point of damaging leaves, it isn't scale IMO.