Now I remember I got the brass extension first. That’s the one I had trouble with, and then went to the fiberglass extension.
As a preventative for peach leaf curl, it’s generally recommended to wait till just about all the leaves are gone. The fungus can overwinter in the leaf scar (after the leaves have fallen). That said, I sprayed for leaf curl on some trees which hadn’t lost all that many leaves. Leaf curl isn’t generally a huge issue here. One spray always takes care of it. That’s why I wasn’t too worried about spraying some trees a little early. Plus I may come back in the spring and spray some copper for frost protection. I did that this year and felt it helped reduced frost losses quite a bit, although I didn’t do any kind of controlled study.
I’ve noticed peaches will keep their leaves quite a bit longer if they have lots of nitrogen. My peaches almost always keep their leaves longer than plum. But as Brady points out, it depends on the variety of the plum. I have all Euro plums. They lose their leaves fairly early, probably because they have a lot of bac. spot issues here.