I have a multi-trunk trident maple that's been having troubles on two of the trunks this year. While the rest of the plant leafed out nicely and has been thriving, these two trunks have small leaves that are curled in. Recently, they've also started turning yellow. There's some new growth off those trunks, though, but the leaves look the same as the others.

Thinking there might be drainage issues, I watered heavily this morning to see if it drained will, which it did. (Water started flowing out of the bottom almost immediately.) Right now, my guess is that it's either nematodes or a fungal infection, but I wanted to see if I was missing anything. Thanks in advance!