Early this summer, my Chinese elm developed tiny brown spots all over most of the leaves. It was repotted last winter. Any ideas on what might be wrong? Heat wave, maybe? Do I cut them off, hoping to stimulate new growth, or just leave the tree be? I am in the SF Bay area.
Thanks in advance,
Picture would be helpful, just saying
Sorry, I meant to post it but I must have gotten sidetracked.
It could be a watering issue after partially defoliating. I would leave them for the time being rather than stress the tree, watch the watering and see what happens.
Okay, thanks for the feedback.
Hmmm. The patterning doesn’t look like heat stress to me. I don’t have a better guess though.
For now I would monitor it without cutting the leaves and see if the same patterning shows up on new growth.
The spots appeared in mid-May, after I fertilized and there was a heat wave (not too severe). Because of the heat, I started misting the plants mid-day. Once the spots appeared, I applied copper fungicide which made things worse. Other affected species (with varying damage patterns) were European beech, quince, live oak and Chinese elm. I initially thought it was fungus, hence the fungicide. I cut off the worst leaves and got new growth, but these eventually spotted as well.
Maybe it’s a heat thing, and I need to pay more attention to shading next year.
Looks like fungus… due to over watering of the foliage or just plain overwatering.
Thanks, all, for your feedback.