Rust Mites

Pear rust mite damage. Pear rust mite damage.

Pear rust mite damage on leaves.
Pear rust mite damage on leaves.



Rust mites are tiny mites (too small to see without the aid of a microscope) in the eriophyid group. Generally, rust mites are of little concern to fruit growers. Foilage of pear is very sensitive to rust mites, and symptoms can be seen in moderate to high populations. Lower populations can be tolerated, and serve as food for beneficial insects.


Adults overwinter under leaf bud scales of pear and apple, and emerge with new leaf growth in the spring. There are many generations throughout the summer.


  • Russeted fruit
  • Bronzed or necrotic lesions on leaves
  • Stippled appearance to leaves


Treatment is rarely needed for rust mites in Utah. On apples, rust mites can be beneficial in that they may serve as alternative prey for predatory mites that also feed on spider mites. In pear, lower populations can be tolerated, but higher populations may need a miticide or 1% oil treatment.


Starting in mid-spring, look for foilage that is stippled (tiny flecks of white), indicating rust mites.


  • Residential: dormant oil° alone or with carbaryl; sulfur (single application, do not mix oil and sulfur)
  • Commercial: for delayed dormant application Click Here; for fruit present application Click Here

Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.