Peach and nectarine-Eriophyid mites

Includes

Peach silver mite (Aculus cornutus)

Prunus rust mite (Aculus fockeui)

Pest description and crop damage Adult mites are extremely small and require at least a 10X magnifying lens to scout for them. They are light-color, cylindrical and wedge-shaped. Immature mites are similar in appearance, but smaller and often lighter in color. These mites have piercing-sucking mouthparts and feed on the outermost plant cells. Eriophyid mite feeding can cause a silvering or bronzing of leaf foliage, and heavy infestations may lead to premature defoliation.

Biology and life history These mites overwinter as diapausing females in buds immediately under the bud scales, or in cracks along the bark. As buds expand in the spring, females leave their overwintering sites and begin feeding, then after a few days lay eggs. In the spring, eggs may take two weeks to hatch, but by midsummer they may hatch in as little as 3 to 4 days. There are several generations per year. As the foliage deteriorates in late summer, diapausing females are produced.

Pest monitoring Observe the leaves for signs of mite feeding and use a hand lens to check for the mites, particularly in fruit trees with a history of eriophyid mite infestations.

Management-biological control

Phytoseiid predator mites almost always keep these mites under control when broad-spectrum insecticide applications are avoided. Rust mites form a significant food source for these predator mites that also control spider mites, so populations of this eriophyid mite can be tolerated. Hot, dry weather and the hardening off of leaves can also reduce eriophyid mite numbers.

Management-chemical control

Successive sampling during the dormant, delayed-dormant period or early spring can best target pesticide applications towards active and growing populations of eriophyid mites before mite damage causes leaf bronzing or silvering. Do not apply these products after the damage has been done.

Management-chemical control: HOME USE

Dormant-season spray

Apply sprays using enough water to cover the tree thoroughly, including small limbs. Apply during the dormant, delayed-dormant period.

  • lime sulfur-Some formulations are OMRI-listed for organic use.
  • superior-type oil-Some formulations OMRI-listed for organic use.

Growing-season spray

  • carbaryl
  • sulfur-Some formulations are OMRI-listed for organic use.

Management-chemical control: COMMERCIAL USE

Spring and summer sprays

  • pyridaben (Nexter 75WSP) at 10.67 oz/a. REI 12 hr. PHI 7 days. Do not exceed two applications per season.
  • wettable sulfur-Formulations and rates vary; refer to product label. REI 24 hr.