Gall mites effect a number of trees such as elm, maple, willows, basswood, and various shrubs. Mites are small wormlike creatures 0.2 mm long with two pairs of legs. The females over winter in the bark of the tree. In the spring they move onto the foliage and stimulate the formation of a gall. The opening can be on either the lower or upper surface of the leaf. Then they lay their eggs inside the gall which develop into male and female mites. These males and females then continue the cycle. The galls on the leaves do not harm the tree, they only cause deformities of the leaves with a large infestation. When the galls are visible it is too late to fix the problem. To prevent theis from happening in the future one can root drench with benlate, (benomyl) next spring as the new leaves are emerging.
Compiled by: Dr. Bill Paton and Vicki East