General Information

Thrips

Despite their small size, thrips are a consistent pest of seedling cotton. Tobacco thrips are the most common species observed in Tennessee, but several other species may also occur. Winged adults migrate into fields when seedlings emerge. Adult and immature stages feed by puncturing leaf cells and emptying their contents. Injury causes foliar deformity (leaves crinkle and cup upward), stunting, delays in maturity, and may cause stand loss. Preventative in-furrow insecticides or seed treatments are recommended. A foliar treatment may also be needed in some cases. Tobacco thrips have recently developed resistance to some neonicotinoid insecticides such as thiamethoxam (i.e., Cruiser). For more information visit the Cotton Insects Thrips Fact Sheet (W026).

The presence of deformed, crinkled leaves and a silvery color is often a sign of thrips infestations. Scouts should visually assess the level of injury on emerging leaves. Numbers of thrips can be sampled by vigorously shaking/thumping seedling plants over a white-surfaced container (e.g., cigar box or Cool Whip container). A 5-10 X hand lens is suggested to help distinguish adult and immature stages.

An online tool, the Thrips Infestation Predictor for Cotton, was developed by North Carolina State University and predicts the intensity of tobacco thrips infestations and injury to seedling plants based of location, planting date, weather conditions.

In-furrow insecticides or seed treatments are recommended. Treatment is recommended, on non-ThryvOn varieties, prior to the third leaf stage when an average of one or more thrips are found per plant, especially when immature thrips are present and there are obvious signs of injury on newly emerged leaves. ThryvOn varieties should not require a thrips overspray even in the presence of adult or immature thrips or damage not exceeding 3.0 on a 1.0 to 5.0 scale.


Management options

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* Not recommended as a standalone treatment for thrips control.

** Radiant SC is suggested if western flower thrips are present in significant numbers. The use of an adjuvant is recommended when using Radiant SC or Intrepid Edge for control of thrips, although several herbicides that are commonly co-applied with thrips application can act as an adjuvant.

*** Tobacco thrips resistance to organophosphate insecticides is increasing, use with caution.

**** General rating for typical thrips control vs. rating specific for western flower thrips (WFT).

  • It is generally best to make any foliar insecticide applications by the second leaf stage. More than one foliar insecticide application is rarely justified.
  • A preventative foliar application is often suggested under adverse growing conditions such as cool weather.