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Pest Alert: Stink Bug Populations on the Rise Entering August

August 10, 2020
This agronomic image shows stink bug injury to cotton

Stink bugs are typically seed feeders, making internal injury to cotton bolls the main concern for growers.

Southern cotton and soybean growers deal with stink bugs year after year, and the 2020 season is proving to be no different.

Consistently a difficult-to-manage pest, experts across LA, TN, GA, MS and SC are warning growers of an increasing stink bug presence. Tom Pegram, an Agronomic Service Representative with Syngenta, says the Southeast is experiencing a fairly robust population of stink bugs, including brown, green, Southern green and marmorated brown stink bugs. These economically damaging pests often transition into cotton and soybeans from corn fields. Pegram warns that stink bugs can reduce the quality and potential marketability of the crop through feeding damage, causing cotton bolls to hardlock.

Thresholds vary by crop – particularly in cotton, which is managed with a dynamic threshold. When cotton begins to bloom, the threshold is 50% damage and reduced to 30% damage in the second week of bloom. In weeks 3-5 of bloom, where many fields are currently, the threshold is 10% damage. Seed soybeans or edible soybeans have a threshold of about 2.5 stink bugs per 15 sweeps. Grain soybeans differ slightly, with a threshold of 5 stink bugs per 15 sweeps.

  • MS entomologist Angus Catchot, Ph.D., says in his August 5th pest patrol alert that while he’s been watching redbanded stink bug populations in soybeans simmer, they’ve taken a turn for the worse. He says they’ve seen numbers quickly build between the R5, R5.5 and R6 growth stages as redbanded stink bugs flock into soybeans during pod-fill. Catchot warns growers they’ll likely see a push of stink bugs as soybeans continue to mature.
  • SC entomologist Jeremy Greene, Ph.D., reminds growers in his recent pest patrol alert that we’re heading into a time of year when stink bug pressure is typically high. Greene encourages growers to treat appropriately, and subsequently monitor injury weekly to observe insecticide efficacy as crops move into their most susceptible yield-loss window.
  • Entomologist Scott Stewart, Ph.D., notes that stink bug pressure is continuing to build in TN. In his most recent pest patrol alert, Stewart says he counts 1 stink bug as the equivalent of 3 tarnished plant bugs because of their notable damage potential if not checked and controlled in a timely manner.

With the potential for 2 stink bug generations per year, Pegram encourages growers to pull samples, since anything above threshold levels triggers an insecticide spray.

Besiege® and Endigo® ZC foliar insecticides are strong options to power through stink bugs in soybeans and cotton. Besiege provides long-lasting, broad-spectrum control of lepidopteran pests with its combination of 2 active ingredients for trusted resistance management. Similarly, Endigo ZC combines 3 industry-leading chemistries for quick knockdown and extended residual control to get ahead of economically damaging pests in soybean crops.

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All photos are either the property of Syngenta or are used with permission.