How dry has it been there. I haven't heard of it in maples but I wonder. I had in my blueberries some similar brown. I found it on the bushes in lower lying areas of the fields. My theory is that they developed less of a root system because the always "have moisture" Then a drought hit and the shallowest rooted ones suffered browning of the leaves while bushes on higher ground fared OK. My elevation difference over my 4.5 acres of blueberries is only about 1.5' max.
I wonder if you had something similar. Too few fine root hairs to take up moisture?
Dave
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.