A lot has changed in the quarter of a century that has passed since the advent of pyrethroids for cotton insect control. Crop consultant Virgil King of Lexington, Miss., has seen the arsenal of insect control products available to farmers come full circle more than once in the 25 years he has been scouting cotton fields.
King, who serves as president of the Mississippi Agricultural Consultants Association, shared his experiences with cotton insect control at the 48th conference of the Mississippi Entomological Association at Mississippi State University in Starkville, Miss.
King first got a glimpse into cotton insect management in 1975 while attending his first Extension scouting school. “I remember the late 1970s being a very difficult and critical time in cotton production. Insects, like the tobacco budworm in particular, were very difficult to control, and cotton yields were low. We were trying to improve our yields and fight insects using products like methyl parathion, Guthion and toxaphene.”
All of that changed a few years later, he says, with the introduction of a new class of chemistry called pyrethroids. “Pyrethroids were really a salvation to the industry.”
It was nothing like we had ever seen before. We'd put these products in the field, then go back into the field to scout for insects, and we couldn't find anything behind them. The fields were just cleaned up of all insects,” he says. “At that time, I thought that anybody could put on the title of consultant and go to the field and be successful. If a fellow could determine which insects were out there and could time his pyrethroid applications accordingly, he could produce a good crop.”
Beginning in the late 1980s, however, King began to see some insect control failures with pyrethroids. “We began to notice some resistant tobacco budworms. We also began to hear talk of things like resistance management, tank mixes, and a window of use for pyrethroids, in the attempt to save this very vital class of chemistry.”
The incidents of control failures increased into the early 1990s, according to King. In addition to reports of crop damage due to tobacco budworms, growers began experiencing beet armyworm control failures in the mid-1990s.
“I came full circle from where I started in 1975. I entered the crop consulting business in a time when things were bleak and insects were hard to control, and in 1995 I was right back to where I started. It was during this time that we got a glimpse of what the transgenics could offer farmers.
“Now, we're back in a cycle,” he says. “The introduction of transgenic varieties has greatly affected our cotton production and has given us the ability to control tobacco budworms again. The introduction of the boll weevil eradication program has also made a great impact on what's going on with cotton production right now.”
That's important now more than ever before, he says, as growers lose some of the tools in their pesticide arsenal. “We're continuing to lose some of our broad spectrum insecticides because of their effects on the environment, or peoples perceptions of their effects on the environment. We do have newer insecticides available, but they are much more expensive and much more specific to individual pests.”
While the introduction of transgenic crop varieties, combined with the eradication program, has greatly aided growers' battles with crop pests, it has also somewhat changed the pest spectrum they face in their fields.
Since the boll weevil eradication program began in his area, King has had increasing problems with aphids, whiteflies, stinkbugs and plant bugs. To adequately control this ever-changing pest spectrum, he says, growers and consultants must re-learn the scouting techniques required for these insects, while also figuring out exactly how they are affecting the crops, and what population thresholds should be used for treatment.
“We're also seeing a greater bollworm problem in our transgenic cotton varieties. Whether the bollworm is adapting to this type of technology or not, I don't know,” he says. “We need to continue to work with the transgenics so we can have a better understanding of how they work, and how to use them more effectively. I think there are still a lot of questions out there about the transgenics and how they affect our production decisions.”
Satellite imagery may be another potential tool to assist growers in their battle against damaging insects. “Using GPS yield maps may not only help us know which areas are limiting production in the field, but I think, will eventually answer some of our insect control questions,” he says.
However, King says, “The biggest and most important tool that we need in cotton insect control is still money.
“We need a return on our investment. We need for our commodities to be worth fair market value so we can continue to implement new ideas and new tools, and all of the tools we'll be using over the next few years are going to depend on money,” he says. “As a consultant, I've done everything I could for my producers to keep their inputs down and still try to produce a profit. This is a time that is critical for agriculture, and we've got to do everything we possibly can to make ourselves more profitable.
“I've told several of my growers this year, it's not how much cotton we can grow, it's how much profit we can make on the crop that we do grow. What is going to keep us in business is not trying to produce three bales of cotton per acre, but trying to make as much money per acre as is possible,” he says.