I ordered several small maples this spring, and one of them appears to have been infested with spider mites. I've never had mites before in my garden, so I didn't recognize the problem right away. The infested maple was slow to leaf out, and I kept finding fine webs around the branches near the tips. New growth soon turned black and died. The mites appear to have spread to some of my other maples. I have been spraying them with insecticidal soap, which seems to be keeping the problem from getting worse but not entirely stopping it. Is there a better treatment than insecticidal soap for spider mites? I would prefer to avoid highly toxic insecticides, but don't want to lose all of my maples either. Can soap be harmful to my other maples? Some of them have developed blackened leaves at the growth tips and dropped a few seemingly healthy leaves since I sprayed them with soap, but I haven't noticed any webbing on them. Also wondering if I should go ahead and cut back the maple that was originally infested with mites. The new growth at branch tips is all either dead, blackened in appearance, or just doesn't look good.
Your first course of action should be to inform your supplier of the problems you have encountered..........spider mites hate cool wet conditions, so just the wetting action of the soap is probably helping to control the infestation...........predatory mites to eat the spider mites are available........its a shame the plants weren't clean when you got them :(
dawgie, Had a bit of a problem myself last summer. See http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=9218 I'm happy to report that all seems well, now. I never pruned back any of the damaged areas and they all seemed to push new buds this spring. Bryan