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EB1711
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| Maple leaves often develop small growths or deformities called galls which are caused by microscopic mites known as maple bladder gall mites, Vasates quadripedes. They occur almost exclusively on silver or soft maple. | ||
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Maple bladder gall mites are approximately 1/125 inch in length and cannot be seen with the naked eye. They are white or pinkish and have two pairs of legs. Mites overwinter as adult females on the bark of host trees. As spring approaches and new leaves develop, they move from the bark onto the leaves where they feed and lay eggs. |
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Damage |
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The mites feed on the undersurfaces of leaves. Their feeding activity causes a reaction in the plant tissues and results in plant production of galls on the upper surfaces of damaged leaves. The galls are globular and vary in size, the larger ones about l/10 inch in height. Galls are green when first forming, then turn red, and finally black as the season progresses. As a gall becomes larger, a cavity forms inside it with an opening on the lower surface of the leaf. This serves as an entrance for gall mites. When the galls are fully formed, the mites feed largely inside the gall cavity. |
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Control |
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| The presence of galls, even in considerable numbers, does not usually harm trees. Rarely does a severe infestation cause serious damage. The problem is largely one of unsightliness. There are registered products available should the problem be severe enough to warrant control. They should be applied in spring before leaf buds open. The names of currently registered pesticides can be obtained from your local county Extension agent. | ||
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(Photograph courtesy of Ohio Agricultural Experiment Station) |
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A.L. Antollelli, Extension Entomologists WSU Puyallup College of Agriculture and Home Economics Washington State University Cooperative Extension bulletins contain material written and produced for public distribution. You may reprint written material, provided you do not use it to endorse a commercial product. Please reference by title and credit Washington State University Cooperative Extension. Issued by Washington State University Cooperative Extension and the U.S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation. Evidence of noncompliance may be reported through your local Cooperative Extension office. Trade names have been used to simplify information. No endorsement is intended. Revised from and replaces EM4361. May 1992. A. Subject Code 352. |
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