I am having this problem on a few of the maples I am growing as pre-bonsai. Does this look like powdery mildew or maybe verticillium wilt? I had the trees in partial shade because it is so hot where I live, but maybe the environment is too damp. They are in 20" fish baskets to develop the roots, so they need to be watered everyday. I’ve moved them out in the sun for now, but some of the leaves are starting to crisp at the edges. Perhaps this isn’t the best variety to be growing in my area … they are not named plants, but seedlings (bought as 12" tall plants). Any advice would be appreciated.
Thanks,
Maryann
That looks like powdery mildew to me. I have two Norway maples that get it every year. It’s on landscape trees in the area so I’m sure spores are continually floating over to my trees. If you Google powdery mildew you’ll get a all sorts of remedies. I try to spray my affected trees with propiconazole, which is a systemic fungicide, at the first sign of powdery mildew. It won’t kill your tree, but it is unsightly.
Thanks, Roger. I appreciate your post.