Spruce adelgids: Time to control nymphs
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.
If you have had problems with Cooley spruce gall adelgid on Douglas-fir or spruce or Eastern spruce gall adelgid on Norway, white or Black Hills spruce, this is the time to apply a registered insecticide to control the overwintering nymphs. The nymphs live and develop inside the galls until late summer when the galls open and the nearly mature nymphs emerge and settle on the needles. Here they become adults and lay their eggs. When these hatch, the resulting nymphs settle near the buds and overwinter, completing the cycle.
Spray with a currently registered insecticide in late September or October and/or again in early April to kill these overwintering nymphs. Some growers have timed this application when the red maples begin to turn red in the fall. Make sure to get good coverage.