Apple-Thrips

Includes

Pear thrips (Taeniothrips inconsequens)
Western flower thrips (Frankliniella occidentalis)

Pest description and crop damage Adult thrips are small (about 0.04 inch long at maturity), slender insects with fringed wings. They are generally white when young but brown or black when mature. Larvae are very tiny and difficult to distinguish without magnification. In apples, thrips feed on developing fruits which causes a white "pansy spot" to develop.

Biology and life history The western flower thrips has several generations and is a widespread problem on tree fruits and other crops in the Pacific Northwest. Damage to apples is during bloom, when female thrips lay eggs into developing fruit. A pale area, known as "pansy spot," develops around the scar where eggs were deposited, and is especially noticeable on light-skin apple cultivars. If only one spray is applied, pink and petal fall give equivalent control.

The pear thrips has only one generation and destroys the fruit buds and flowers of fruit trees during bloom. This pest has recently become a localized problem in the mid-Columbia fruit-growing area, especially in orchards that border habitat with native hosts such as maple and other deciduous trees. Use a beating tray during pink stage to monitor and detect immigrating pear thrips along border rows of orchard. Pear thrips is best controlled at early pink.

Management-cultural control

Manage weedy vegetation within and around the orchard (especially blackberry, mustard and radish). Do not mow cover crops or weeds when stink bugs are present, since mowing may cause thrips to disperse to the fruit trees.

Management-chemical control: HOME USE

Stages 5-6: Pink spray

  • acetamiprid
  • azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
  • Beauveria bassiana-Some formulations are OMRI-listed for organic use.
  • carbaryl-Highly toxic to bees.
  • gamma-cyhalothrin-Highly toxic to bees.
  • insecticidal soap-Some formulations OMRI-listed for organic use.
  • kaolin-Applied as a spray, it acts as a repellant to some insect pests. Some formulations are OMRI-listed for organic use.
  • lambda cyhalothrin-Highly toxic to bees.
  • malathion-Highly toxic to bees.
  • permethrin-Highly toxic to bees.
  • plant-derived essential oils-Some have shown efficacy against thrips. Some formulations are OMRI-listed for organic use.
  • pyrethrins (often as a mix with other ingredients)-Some formulations are OMRI-listed for organic use.
  • spinosad-Highly toxic to bees. Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin-Highly toxic to bees.

Management-chemical control: COMMERCIAL USE

Stages 5-6: Pink spray

  • Chromobacterium subtsugae (Grandevo) at 2 to 3 lb/a. Under heavy pest populations, apply a knockdown insecticide prior to use or in a tank mix, use the higher label rates, shorten the spray interval, and/or increase the spray volume to improve coverage.
  • spinetoram (Delegate WG) at 4.5 to 7 oz/a in up to 100 gal of water per application. Do not exceed four applications or 28 oz/a per growing season. PHI 7 days. [Group 5]
  • spinosad (Success Naturalyte) at 6 to 10 oz/a in up to 100 gal of water per application. Do not exceed 29 oz/a per season. PHI 7 days [Group 5]
  • spinosad (Entrust 80WP or 2SC) at 2 to 3 oz or 6-10 fl oz /a in up to 100 gal of water per application. Do not exceed 9 oz or 29 fl oz /a per season. PHI 7 days. [Group 5] OMRI-listed for organic use.