We do have nematodes but I don’t think they would just affect certain limbs on a tree while the rest are unaffected. I think a general decline of the whole tree would be a symptom of nematodes.
Two things I can think of are cold and boron. We had a cool November and early December and then 2 really warm weeks before cooling back to a normal winter, never dropped below the 20’s. Nothing broke dormancy but buds did swell. Maybe this was enough to cause damage later.
Boron deficiency causes some of these symptoms and I added Borax to some plants that have displayed small signs last year, mainly jujube and apple. None was added to any pawpaw because they have done great for 5 or six years. Jujube are doing much better this year. Last year I went to graft onto my Sugar Cane and could not find a live limb on the tree, it did grow nicely from the main trunk after pruning it back to a large whip.
Another smaller pawpaw mostly dead, just growing from one area. The small limbs on apple and persimmon were pruned out, don’t have pics of them. I also have a third pawpaw that looks the same.
