Not Completely Business as Usual for Thrips
Cotton growers will be living in different worlds when it comes to early season insect control in 2023. Some will have access to Bollgard 3 ThryvOn cotton; others won’t.
While that might not seem fair, the reality is that Bayer, which owns the technology, just recently received all the foreign government approvals needed to permit a full commercial launch of the trait.
Growers who have access to ThryvOn trait varieties will face a different treatment scenario for early season insects than for those who don’t, according to Extension and university researchers.
No Need to Overspray
“As a group of entomologists across the Cotton Belt, we don’t recommend foliar sprays for thrips on ThryvOn,” says Dr. Sebe Brown, Extension Entomologist with the West Tennessee AgResearch and Education Center. “We don’t see an economic benefit, but it still needs to be watched. I’m not a fan of planting something and forgetting it. But there’s been no scenario in the five-plus years we’ve looked at ThryvOn that we have seen a need to overspray.”
“Growers shouldn’t be alarmed if there are thrips in the field or if they see minor damage, because we commonly see both,” says Dr. Whitney Crow, Entomologist with the Mississippi State University Extension Service. “But that doesn’t mean it needs to be sprayed.”
Tackling Thrips Resistance
Without ThryvOn cotton, Mississippi State historically has recommended an Aeris seed treatment or Gaucho (Bayer Crop Science) with either acephate overtreated or acephate in-furrow.
“We’ve been sending thrips populations to the University of Tennessee where they’ve been testing for resistance,” Crow says. “In the last several years, we’re seeing an increase in resistance to organophosphates, specifically to acephate or Bidrin (AMVAC).
“So we’re not recommending those at planting,” she notes. “We are recommending AgLogic, Gaucho, or Aeris seed treatments. Those are the best options unless you want to do Admire Pro (Bayer Crop Science), an in-furrow option. If thrips pressure is heavy — which seems to be occurring more frequently and our seed treatments aren’t getting us through that window of susceptibility — the only option we have for foliar applications is Intrepid Edge or Radiant (Corteva).”
If availability or price is an issue and farmers must apply acephate or Bidrin, “they should expect minimal control,” she says.
“Thrips are here every year and sometimes at high levels,” says Dr. Glenn Studebaker, Entomologist with the University of Arkansas System Division of Agriculture. “If growers can plant ThryvOn, they shouldn’t have to make foliar applications for thrips.
“Growers will see some adults fly in,” he continues. “But they shouldn’t see much damage, and they shouldn’t have to spray for thrips. Early season plant bugs? ThryvOn does a good job of controlling them, but it’s not as good on plant bugs as it is on thrips.”
University of Arkansas entomologists are continuing to research ThryvOn and plant bug thresholds, adds Studebaker.
“For now, we’re recommending spraying ThryvOn using our normal tarnished plant bug thresholds.”
For growers without ThryvOn, the biggest challenge may be thrips on early planted cotton.
“If it’s cold and cotton is struggling and gets slowed down, thrips can be more damaging,” he points out.
“We are seeing resistance to acephate, which has been our go-to product for thrips in early season. If growers are using acephate, we’re recommending they go up to 0.5 pounds of active ingredient for early season control of thrips or go with a spinetoram product like Radiant or Intrepid Edge. It still works well on thrips.”
Seed treatments have also been effective. “Again, that goes back to if we plant early and it’s cold, we can only expect a seed treatment or even an in-furrow like aldicarb to provide three weeks of control,” notes Studebaker. “If you’re seeing thrips coupled with plant damage, we recommend spraying.”
GET THE NEWSLETTER TODAY!
