Tree owners and tree managers are encouraged to learn about the life cycles of these pests and learn that no lasting damage will result. Talk to the plant supplier to see if the tree cultivar has a history of leaf gall problems or not. Dormant Oils - Use of dormant oils on maples is discouraged because leaf and twig damage can result unless the tree is truly dormant. However, some reports of success have been made where the trunk has been drenched with dormant oil to kill the overwintering stages of the bladder gall and spindle gall mites. If these products are to be used, they have to be applied precisely when the new leaf buds are opening.
Most sprays have little, if any, effect because the window of opportunity is very short.
Once the gall has formed, it is too late to make an application. See Bulletin 504 for a listing of currently registered pesticides for management of gall mites and gall midges. However little evidence of success has been found in the current literature. Once the gall has formed, it is too late to make an application. See Bulletin 504 for any currently registered pesticides.