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May 19, 2004

Maple petiole borer has been reported from Douglas and Shelby counties. This is a sawfly that tunnels into the petiole of various maple species. The larva feeds on the inside of the petiole until the petiole breaks near the leaf blade, resulting in the ground becoming littered with fallen leaves having short petiole stumps. The sawfly larva continues to develop in the leafless petiole on the tree, dropping later in the season to the ground to pupate. Although clients become alarmed about the number of fallen leaves, they represent a small proportion of the leaves on the tree with little impact on its health. There is no practical control for this pest. Realize that many trees drop leaves at this time of year in response to hot, dry weather. Those fallen leaves have complete, intact petioles.

Gypsy moth treatments by the Illinois Department of Agriculture and USDA APHIS are scheduled for the next 2 to 3 weeks in portions of Cook, DuPage, Kane, McHenry, and Will counties. Applications are scheduled to start on May 18, depending on the weather.

Author: Phil Nixon Susan Grupp Suzanne Bissonnette


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