I have 16 Japanese maples; six are in pots. None are showing any signs of stress - not even much crispiness since it has been so cool and moist.

One crimson queen in a 25" glazed pot; first full year; in afternoon shade; no signs of borers. Underneath leaves are turning a beautiful red-orange. That would be nice if they weren't then falling off. Can't be too little water, because I would imagine they would be crispy>>then fall off.

I'm looking for help as to what else causes this type of stress on one particular tree.