Not many choices. Try wettable micronized sulfur, but check the label for phytotoxicity in maples. I didn't find maples listed on the label.

Here is a link that might be useful: IPM for spider mites

xman, my experience (and supported by various J. maple growers) is that their foliage is quite vulnerable to phytotoxicity from a variety of sources - they just don't like stuff sprayed on their leaves. And hosing down plants with water regularly is a generally accepted and recommended treatment to control spider mites. Do you find it ineffective? I've never had a problem with mites and my maples, but it sure works well for other plants.

thanks for the replies.

gardengal, I have not tried hosing with water yet, when I saw all the spider mites, I panicked and sprayed all the leaves with safer insecticidal soap. In a couple of days all the leaves dropped off(that's when I checked their website to see if I can use it on maples).
I will try the hosing next season, maybe just hose them down every couple of weeks to keep on top of things.

thanks,
xman

I had a dissectum that came down with a bad infestation of spider mites this last summer. Things got pretty bad because I had no previous experience with mites and it took me a long time to figure out what was wrong. Once I did, I simply set a sprinkler right under the tree and blasted the underside of the foliage for 5 or 10 minutes every two or three days. This tactic, coupled with cooler early September temperatures, yielded good results. The tree actually pushed some new foliage where the mites had done the most damage.

Tam