Poplar and willow borer damaging pussy willows in nurseries

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

The poplar and willow borer is a small (0.25-inch long) dark brown to black weevil with a distinct white patch at the tail-end of the elytra. The larvae of this weevil bore into the stems of many types of willows and poplars, with most of the damage being found in nurseries or in recently planted trees. This spring it seems that some batches of pussy willows sent to Michigan nurseries from nurseries in other states arrived heavily infested with this weevil. The tunneling damage causes the trunks to swell and crack, sometimes breaking in wind storms. The adult weevils will start emerging in mid-July and remain active in August and September. Larvae cause tunneling damage in late summer, fall and early spring. In southern Michigan, we usually have one generation per year. Infested pussy willows can be treated with a foliar spray in late July to kill adult weevils before they lay eggs, or with a basal soil application of Discus or Flagship in July.

Poplar and willow borer adult
A poplar and willow borer adult.

Did you find this article useful?