In Alabama cotton: Researchers improve insect control

Researchers in north Alabama's Tennessee Valley continue to look at new and better ways of controlling the most prevalent cotton insect pests, including thrips, aphids and plant bugs, says Barry Freeman, Auburn University Extension entomologist.

Thrips trials

“We've been running a thrips trial here for many years,” said Freeman at a recent cotton field day in Belle Mina. “It's been a mild, average year for thrips in the Tennessee Valley, and none of our treatments worked real well. Some of the seed treatments actually led the tests in thrips counts and damage ratings. The seed treatments out-performed Temik, even at seven weeks after planting, and that usually doesn't happen.”

Adage or Gaucho seed treatments generally are considered 28-day compounds, he says, but they continued to show good thrips suppression this year after seven weeks.

“Temik didn't fare great this year, but that's not surprising. Whenever you get a lot of rain at one time, such as three to four inches you'll lose some Temik, and that happens in about one out of every 10 years. If you get four inches of rain over about six weeks, you won't lose this product. It's a consistent compound, and it still held down thrips numbers for some time,” notes Freeman.

All compounds tested on aphids performed well this year, he says.

Turning to plant bugs, Freeman says he has looked at about 16 trials at Belle Mina this year. “We sprayed for plant bugs just as they came in June, and we sprayed again in July. We have a lot of data, having looked at Capture, Karate, Centric from Syngenta and Assail — a product from Aventis that isn't yet on the market.

Other products

“We also looked at Leverage from Bayer, Vydate, Steward, Calypso from Bayer and several DuPont combinations. Orthene was used as a standard in the trials,” he says.

Capture and Karate both looked excellent in the trials, says the entomologist. “One of the rates of Century looked pretty good and Assail looked pretty good. Everything else looked moderate. The products gave good suppression over the check plot, but it wasn't anywhere near 90-percent control. Plant bugs are tough to kill, and coverage becomes critical in July.

“One-third pound of Orthene didn't perform up to my expectations. It's a good compound, but other states, including Mississippi, have had to raise the rates on some of the organophosphates. It may be time for us to take a look at that.”

In reviewing the insect season thus far in the Tennessee Valley, Freeman says thrips pressure has been very moderate. “We had an aphid flare-up in early June. Plant bugs were late coming in June, but they just kept coming once they were here.

“Depending on where you were located, you probably needed to spray from one to three times for plant bugs. We saw more worms in June that we've been accustomed to seeing in the past two drought years.”

Growers in north Alabama saw a corn earworm flight in late July, and it quickly turned into a tobacco budworm flight, says Freeman. “Some producers were seeing some control problems as they were trying to control worms with pyrethroids. These problems were seen on about 30 percent of our non-Bt acres. Traps were loaded up with corn earworms in early August.”

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