If you need a refresher course on the destructive power of the boll weevil — the pest that cost U.S. growers billions of dollars in treatment costs and lost yield over many decades — you have only to go to Brazil, says Angus Catchot, a Mississippi State University Extension professor of entomology.
He and Darrin Dodds, associate Extension/research professor of plant and soil sciences at MSU, took a group of research students to the World Cotton Research Conference in the South American country, and spent a few days in the field looking at cotton and other crops.
“I had almost forgotten how bad boll weevils can be,” Catchot said at the joint annual meeting of the Mississippi Boll Weevil Management Corporation and the Mississippi Farm Bureau Federation Cotton Policy Committee, where it was announced that Mississippi is now into the eighth season of weevil-free status, thanks to the success of the years-long beltwide weevil eradication program.
“Brazilian cotton farmers were making 25 to 30 applications for boll weevils,” he says. “It’s unbelievable how bad the weevils were. In that area, weevils were pretty much putting them out of business.
“It was a good experience for our students to see this firsthand — most of them had no idea how devastating the pest can be. That we’re into our eighth year with no weevils in Mississippi is a testament to the hard work and investment of Mississippi and U.S. cotton growers.”
Here at home, Catchot says, “This been one of the worst thrips seasons we’ve had in recent years. We’ve made multiple applications on a lot of acres. We had dry weather during much of that time, and thrips tend to be worse during dry periods.”
Adding to the problem, he says, is increasing resistance to the common seed treatment insecticides used by cotton growers.
Hairy varieties may be less susceptible to thrips
“In the last couple of years, we’ve been observing that certain cotton varieties are much more susceptible to thrips injury than others — and that variety choice can make a really big difference in a bad thrips year. We’re now beginning to identify some of these varieties.”
Thiamethoxam has not been performing well on thrips, Catchot says, “and last year we predicted, based on what we were seeing in the field, that we would begin to experience failure of imidacloprid this year — and that has happened; it has failed in a lot of places.
“That has left us with a couple of mixtures. Even though it contains imidacloprid, Aeris is still working OK, because it has another component that’s helping maintain thrips control.
“Another practice we’ve encouraged at all of our meetings this year is the use of acephate seed treatment on top of imidacloprid — and I wish more people had listened. Those who have followed the advice this year were extremely pleased. Keep it in mind for next year. Although it doesn’t last as long, it makes a big, big difference when you add acephate as a seed treatment with your other insecticide.”
Plant bugs have been below the norm in intensity going into July, Catchot says. We’ve been getting calls asking where the plant bugs are. We’ve had some some hot spots, but most of the callers have told us they weren’t finding much in the way of plant bugs. That will change as we move through the season — it always does. But after what they’ve had to deal with from thrips, most growers have had a pretty good reprieve from coping with plant bugs. As we’re moving into bloom and fruit retention, plant bug numbers are moderate to lighter than normal, and that’s welcome news.”
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