eriophiid mite damage on leaves

Eriophyid mite damage on blackgum. Photo: Lorraine Graney, Bartlett Tree Experts, Bugwood.org

Updated: March 23, 2021

Key points

  • Adult eriophyid mites are very small (<1mm). A hand lens is needed to see them.
  • They are spindle-shaped, with four legs and may be white, yellow or orange.
  • There are several generations a year.
  • They overwinter in bark crevices and under bud scales.
  • Some species feed on the leaf surfaces of both deciduous and needled evergreen trees causing the foliage to turn olive-tan.
  • Others cause leaf galls (some appear fuzzy) on beech, leaf blisters on pear, or damage buds of yew and flowers of ash.
  • Eriophyid mites may cause witches’-broom galls in hackberry, Scotch pine, and poplar.
  • They are the main vector of rose rosette disease
eriophyid mites

Eriophyid mites. Photo: John Davidson, University of Maryland

fuzzy gall on river birch leaf produced by eriophyid mites

Felt-like leaf gall on river birch caused by an eriophyid mite. Photo: Steven Katovich, Bugwood.org

Management

  • To check for eriophyid mites, look for off-color foliage, leaf or bud abnormalities.
  • Use a 10X or 20X hand lens.
  • Large mite populations often produce many elongate, white shed skins.
  • Plants with a history of eriophyid mite damage should receive a dormant oil spray to kill overwintering stages.
  • To prevent heavy gall infestations, spray with horticultural oil at bud break (summer rate).
  • Leaf feeding mites can be controlled with a spray of horticultural oil (summer rate) whenever they reach damaging levels. Check horticultural labels carefully for instructions and safety precautions.

Rev. 2020

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