Pine (Pinus)-Eriophyid mite

Trisetacus spp.

Pest description and damage Eriophyid mites are tiny, elongated, whitish or tan mites that feed under bud scales or in the needle sheaths, often down in the fascicles at the needle base. Two types of symptoms of eriophyid mite feeding are browning of the newly emerging shoots and yellowing, twisting, distortion, and stunting of needles. Occasionally there is development of numerous buds where a single bud has been infested (rosetting). Severe infestations may kill needles and cause needle drop, leaving naked branch tips. Rosettes may develop into witches' broom growths. Two-needle pines, particularly lodgepole or shore pine, are affected.

Biology and life cycle Little is known about these pests. They presumably overwinter as eggs deep in the needle fascicles and hatch in spring as new growth begins.

Management-cultural control

Prune out heavily infested branch tips.

Management-chemical control

See:

For more information

Antonelli, AL. 2003. Pine Eriophyid. EB1639E. Washington State Univ. Extension (http://cru.cahe.wsu.edu/CEPublications/eb1639e/eb1639e.pdf)