Published by Utah State University Extension and Utah Plant Pest Diagnostic Laboratory
ENT-242-23
August 2023
Poplar Bud Gall Mite Marion Murray, Extension IPM Specialist and Ryan Davis, former USU Arthropod Diagnostician
Quick Facts • Adult poplar bud gall mites are microscopic, reddish, and spindle-shaped. • Many species of poplars, cottonwoods, and aspens are affected by poplar bud gall mites. • The mites feed inside leaf buds, causing them to swell into woody galls 3 to 4 cm in diameter. • Repeated attacks may stress the tree, leaving it susceptible to other problems. • They are controlled by pruning and insecticide application.
Fig. 1. Early-season gall produced by poplar bud gall mites. Eriophyid mites do not have wings, but their small size
The poplar bud gall mite (Eriophyes parapopuli) is an eriophyid mite. It is microscopic and about one-fourth the size of a spider mite (0.2 mm long). Adults are reddish and spindle-shaped. Poplar bud gall mite hosts include species of poplars, cottonwoods, and aspens. The mite causes woody cauliflower-like galls to develop from leaf buds.
BIOLOGY AND HABITS Poplar bud gall mites spend most of their lives inside their protective galls. They reproduce rapidly with a generation (egg to adult) developing in as little as 2 weeks, giving rise to as many as eight generations per year. Poplar bud gall mites overwinter inside galls on the tree or under bud scales. Mites start activity in April and continue through September. From about May through August, some mites migrate to new leaf buds and form new galls. Mites may remain active inside a gall for up to 4 years.
allows them to infest other trees by drifting on wind currents. Another mechanism of spread is incidental travel on birds and insects.
DAMAGE Feeding by poplar bud gall mite prevents leaf buds from developing into normal leaves and stems. Instead, the buds develop into woody galls 3 to 4 cm in diameter. The galls have a cauliflower-like appearance and are small and green early in the season (Fig. 1). By late summer, they have enlarged and turned a brick red or blackish brown (Fig. 2). Older galls dry out, become hard, ridged and furrowed, and turn a tan or grayish color. These abandoned galls will persist on the tree another season before falling off. Lower branches are usually more heavily infested, with galls occuring primarly on 1-year-old twigs. Branches become stunted, crooked, or have sparse foliage. Several years of repeated attack may cause the ends of the branches to die back beyond the galls. Leaf
Poplar Bud Gall Mite
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