AusBonsai

Hi
My JM in styrofoam grow tub had a bad summer with leaf scorch and dropped most leaves. It then shot out some new growth recently . But whilst it looked ok at first it is slowly turning black and crispy. it’s not heat or scorch related - moved to a cooler spot and lower heat at the moment. Is this fungal? And any recommend remedy?

Looks like fungal infection of some sort.
Check the base of the trunk for signs of black bark. I usually see this in spring when the maples first leaf out and it's much more common where tree roots have been wet and cold for extended periods. Most often it's pots sitting on the ground.
It's possible your roots have been too wet while there were no leaves to absorb water from the pot.

I don't know any cure but a couple of trees have recovered when the pots put up on a bench and watering limited to keep the pot barely damp for a few weeks while new roots grow.
Maybe a fungicide could help and usually doesn't make anything worse.

If there's no black bark there's more hope. I usually just ignore the problem until it goes away - which it usually does.

thanks Shibui. You are right, it’s on the ground and likely a bit much water during a period with no leaves. Thankfully no black bark. i’ve seen that symptom on other trees which rapidly died. i’ll treat with fungicide and cross fingers!