Your spots look like leaf burn from too much sunlight, which could be made worse by keeping the tree in a pot. Why is it in a pot, if you've got it buried in the ground? Once a JM is established in the ground, it is much more resistant to leaf burn. However, if it gets too much sunlight and wind, it will probably always get at least some leaf burn.

Hi, dawgie -- thanks for responding. The tree is in a pot because I don't expect to be in this house long enough to see it mature and I don't really want to leave it behind. So with the thought of taking it with me, I potted it last spring and had it on my deck. I sunk it in a garden over the winter because I thought it might need that additional insulation. It has virtually the same sun exposure that it had last year (west exposure, dappled by pines later in the day, so no more than a few hours of sun). It didn't spot last year. Are you saying that if it were actually planted in the bed, it wouldn't be as likely to burn? Is that due to greater root growth? Guess I might have to rethink my plans to keep it potted.

Thanks for your help.

The spring foliage on J. maples is pretty tender and easily damaged. This looks to me a bit like sun damage amplified by water drops remaining the leaves. Not serious - pretty much just a cosmetic issue. FWIW, this can happen just as easily on young J. maples planted in the ground although older, established trees tend to grow out of it.

There's no harm to growing your maple in a pot, but it does make them more susceptible to leaf spotting and drying out. You might consider repotting it in a larger container. It might just be running out of space for the roots, so it dries out quicker. It might also just be what gardengal mentioned -- spotting caused by water drops on leaves. One of my maples got leaf spotting real bad this spring, even though it's in a fairly shady location on my deck and it's a sun-tolerant variety (Emperor). I had just repotted it and moved it out of the shade too quickly. The leaves burned around the edges, but otherwise it's OK.

This looks like a disease to me. My daughbors japanese maple got it then her other tree beside it got it then my huge silver maple got it accross the street. This sucked and we put up with it for two years, finally she dug the thing up and got rid of it, this year everything is just fine so far. For some reason her tree had it bad.

Your maple has frog eye leaf spot. Caused by Phyllosticta minima. I had the same problem last year and did ALOT of research on finding out what it was and how to fix it. Bad news is this is a disease and not caused from too much sun. The good news is that this rarely does any damage to the tree, it's just ugly to look at. But since we all want beautiful trees, I had to find a way to get rid of this. The consensus everywhere I looked, was to make sure come fall you clean up all dropped leaves and dispose of them so the disease doesn't come back. Chemical treatment is rarely needed. I cleaned up my debris last fall, and so far this year, I do have it on a couple of my maples, but it is far less than last year, so I feel like I'm getting some where with it. Good luck to you!

Thanks for the info, guys. Guess I'll keep an eye on this one. Would this small tree be benefitted by my removing the spotted leaves, in case they're fungal?

Karen

If it's just a few leaves, I would cut them off, but if it's alot, I wouldn't defoliate the whole tree. You can defoliate a tree completely in the summer, believe it or not, and get a whole new flush of growth by the end of the season. This is often done in bonsai, but cannot be done back to back seasons. I have a very young Hogyoku that had the leaf spot on every leaf this time last year. I defoliated it in August, and the tree has responded great. Here are some pics of the transformation in just one year. The tree has really taken off this year and if you look closely at todays pic, I only have about 5 leaves with the spot as opposed to the entire tree last year. I'm going to cut these off shortly.

Hogyoku April 2004 -- Was covered in spots a month later

Hogyoku Oct 5th after complete defoliation in August

Hogyoku May 2005