Shake Your Thrips with ThryvOn™ Technology

March 1, 2023

  • Early-season scouting for thrips and timely decisions are important for protecting cotton yield potential.
  • Poor field conditions that slow cotton seedling growth can increase susceptibility to thrips damage.
  • Planting Bollgard® 3 ThryvOn™ Cotton with XtendFlex® Technology may help reduce the number of insecticide applications needed for control of key thrips species.*

Thrips are one of the most economically important early-season pests for cotton growers. Shortly after planting, thrips can migrate into cotton fields from bordering weeds or fields. Fields that are cool and wet or impacted by herbicide damage, seedling disease, and wind damage can result in delayed cotton growth and increased thrips feeding on the same plant tissue. Feeding can result in curled and gnarled leaves, loss of the terminal bud, blackened leaves, stunted plants, reduced stands, and a silver presence across the field. Plants with damaged terminal buds can have abnormal growth patterns, and heavy damage can lead to plant death.1

Thrips injury in cotton.
Figure 1. Gnarled and deformed leaves on a cotton seedling from thrips damage.

*Scouting is critical to determine which and how many insecticide applications are recommended to avoid economic loss greater than pest management costs (i.e., when economic thresholds are met). Check with your local state extension university for the latest spraying recommendations.

Identification and Scouting

Thrips are very small insects about 1/15-inch (<2 mm) long and can be yellow to brown and gray or sometimes black. They feed on the underside of cotyledons and leaves and in terminal buds and small squares. Thrips may be present as immatures and winged adults and development from egg to adult is typically two to three weeks.

Fields should be scouted twice a week beginning at 50 percent emergence. Select 25 random plants in four sections of the field and look for immature or adult thrips. Look under the leaves and in terminal growth as they prefer tight locations. A pencil or toothpick can help to open the bud when investigating.2

A simple recommended threshold is based on emergence to:

1 true leaf 1 Thrips per plant

2 true leaf 2 Thrips per plant

3 true leaf 3 Thrips per plant

4 true leaf 4 Thrips per plant

5-7 leaves or square initiation

Treatment not typically recommended


University extension researchers have been evaluating ThryvOn™ Technology and updating threshold recommendations as needed. Growers should consult local extension recommendations prior to applying a thrips control measure.

Scouting for thrips is typically not necessary beyond the 5-leaf stage and thrips infestations will vary from year to year and by location. Cotton plants generally outgrow mild to moderate thrips damage by four to six weeks after emergence.


Management

Heavy thrips damage from cotyledon to 2 true leaf stage can have a greater impact on yield potential than later infestations, so it is important to protect cotton seedlings early. There are several insecticide options available for thrips control, however, be mindful of potential resistance. Using a combination of two different insecticides through seed treatments, in-furrow, or foliar insecticides can help provide an effective means to control early-season thrips. Scouting and decisions should be swift as the optimal time to apply a foliar insecticide application is the first true leaf stage.3 If immatures continue to be present after the 2-leaf stage, then this may indicate that the insecticide is no longer active or effective.

Cultural practices can be incorporated to help reduce thrips populations in the field as well as provide additional soil health and weed management benefits. Research in the Southeast found that planting cotton into a cover crop can help reduce thrips populations on seedling cotton by up to 50 percent. In South Carolina, cotton planted into strip tilled rolled rye had the lowest thrips population in the study. Conversely, conventionally tilled fields with no cover crop had the highest numbers of thrips at the cotton seedling stage. Increased residue on the field was correlated with increased suppression of thrips while maintaining yield potential.3

ThryvOn™ Technology is the industry’s first cotton biotechnology trait that provides built-in protection against key thrips and tarnished plant bug species.* In farmer managed 2021 ThryvOn™ Ground Breakers® Field Trials, ThryvOn Technology provided a 72% reduction in average season-long counts of key thrips** and a 6.1% increase in square retention compared to the check.*** ThryvOn Technology is available as part of the stacked trait package in Bollgard® 3 ThryvOn™ Cotton with XtendFlex® Technology.

ThryvOn™ Technology research at NC State University and Texas A&M AgriLife Extension resulted in excellent thrips control with additional in-furrow or foliar insecticides for thrips control not recommended for cotton varieties with ThryvOn Technology.4,5 Consult local extension recommendations or contact your local extension agent for more information.

It is important to consider available thrips management options and how they can be incorporated into current integrated pest management systems.


*Scouting is critical to determine which and how many insecticide applications are recommended to avoid economic loss greater than pest management costs (i.e., when economic thresholds are met). Check with your local state university extension for the latest spraying recommendations.

**48 2021 farmer managed Ground Breakers® Field Trials in the cotton belt (AL, AR, GA, MO, MS, NC, TN, TX) vs the check (i.e., cotton varieties not containing ThryvOn™ Technology) vs cotton varieties not containing ThryvOn™ Technology. 0.375mg ai/seed imidacloprid applied to the ThryvOn Technology seed.

***30 2021 farmer managed Ground Breakers® Field Trials in the cotton belt (AL, AR, GA, MO, MS, NC, TN, TX) vs the check (i.e., cotton varieties not containing ThryvOn™ Technology) vs cotton varieties not containing ThryvOn™ Technology. 0.375mg ai/seed imidacloprid applied to the ThryvOn Technology seed.


Sources

1 Cotton Insects: Thrips (Thysanoptera). 2013. Kansas State University. Department of Entomology. https://entomology.k-state.edu/extension/insect-information/crop-pests/cotton/thrips.html#:~:text=Thrips%20cause%20most%20damage%20to,become%20distorted%20and%20curl%20upward.

2 Thrips. Texas A&M AgriLife Extension. Cotton Insect Management Guide. https://cottonbugs.tamu.edu/seedling-pests/thrips/.

3 Herbert, A., Chappell, T., Huseth, A., Kennedy, G., Reisig, D., Greene, J., Reay-Jones, F., Roberts, P., Toews, M., Jacobson, A., Smith, R., and Reed, T. 2015. Managing thrips in cotton: Research in the Southeast region. Virginia Cooperative Extension. ENTO-182NP. https://cottoncultivated.cottoninc.com/.

4 Reisig, D. 2023. Insect management in ThryvOn cotton. NC State Extension. https://cotton.ces.ncsu.edu/2023/02/insect-management-in-thryvon-cotton/.

5 Vyavhare, S. and Kerns, D. 2023. Managing insects in ThryvOn cotton. Texas A&M AgriLife Extension. https://focusonagriculture.blogspot.com/2023/02/managing-insects-in-thryvon-cotton.html.


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