A Change In Landscape
What were minor pests then are major pests now.
June 3, 2009
Deltapine’s NuCOTN 33B and 35B were introduced in 1996 as the first Bt varieties and they provided outstanding control of the lepidopteran insect complex. Prior to that, tobacco budworms had been almost without peer in cotton pest problems. Budworms, we thought at the time, were on par with the Biblical plague of locusts. Not really, but they might as well have been — we couldn’t control them.
“What was public enemy number one then might not be now,” says Dr. Bill Robertson, the National Cotton Council’s Manager, Agronomy, Soils and Physiology. “A lot of that has to do with the changing landscape of the crop mix.”
Addressing those changes will be one of the topics of this year’s Consultant Conference, which will be held on Monday, January 5, at the Beltwide Cotton Conferences in San Antonio.
“We’re trying to give people a heads up on what to look for and what to do,” continues Robertson, who was the Arkansas Extension cotton specialist when the Bollgard varieties were introduced.
What were called minor pests prior to Bollgard have now become major pests. One of the topics at the Conference will be on one of those – the spider mite. “Spider mites have become much more of a problem over the last four years,” says Dr. Angus Catchot, Mississippi Extension entomologist. “We’ve always had them, but they have become more of a consistent pest – we’re seeing a lot more mite problems early season than we ever have and over a much greater geography.
“A lot of our problems have to do with the reluctance to treat spider mites due to the cost of application,” he continues. “And when we do treat, the chemistry we use only controls spider mites.
“One of the reasons we put this conference together was to address questions on peoples’ minds throughout the Cotton Belt about spider mites as they become more of a pest and their status changes.”
Changes in Refuge
Catchot will be joined by Louisiana Ag Center entomologist Dr. Roger Leonard, who will address thrips, tarnished plant bugs and stinkbugs.
“As we move from Bollgard to Bollgard II, the immediate change that we will see is the reduction in the use of insecticides for caterpillar pests,” says Leonard. “And when we do, we give other insects the advantage in terms of refuge for them to reproduce and infest cotton fields.”
A perfect example of this, Leonard says, is the tarnished plant bug, which is using CRP land and fields of corn and soybeans as refuges.
“Thrips are a general problem,” he adds. “Even though we have the technologies – seed treatments as insecticides and nematicides – we still don’t appear to be gaining much on the thrips problem.”
Another factor in the changing landscape of insect control is crop rotation. “When I started in Arkansas in ’95, there was less than 10% – and probably more like 5% – of our cotton that was in any sort of rotation,” Robertson says. “So over 90% of our cotton acreage was cotton after cotton after cotton. And this is certainly not unique to the Mid-South – it has happened to some degree across the Cotton Belt.
“Looking at it now, nematodes and the Farm Bill have had a lot to do with us going to more rotation, and as a result our pest situation has changed.”
What will make the conference unique is that the Cotton Belt will be broken down into sections and problems addressed on a regional basis.
“In the Southeast, the research is being done on stinkbugs and that’s where most of the damage is coming from,” Leonard explains. “In the Mid-South and even into Texas and Arizona, the plant bug complex is becoming more important. We will try to address these issues.”