With an increased interest in conventional cotton production in central and east Alabama, entomologists are looking at strategies to accommodate the growers who choose this route, says Ron Smith, Auburn University Extension entomologist.
“Last year was a horrific year for tobacco budworms. They lasted for the better part of the month of July, and we lost a lot of fruit during that period,” said Smith at the East Central Alabama Cotton, Peanut and Soybean Tour. “So we came up with a strategy we thought would help minimize that and keep down our costs because tobacco budworm chemistry is very expensive.”
At four state research stations, Smith put in a systems trial rather than replicated small plots, treating every block and every variety, including CT-210; Phytogen 440, with the WideStrike trait but no herbicide technology: DPL 174, with Roundup Ready but no insect technology; DPL 0935; and Stoneville 4498.
“We have managed these as best we could without spending a lot of time scouting insects,” says Smith. “We did not have tobacco budworms like we had last year. Fortunately, the budworm has been completely absent over the state of Alabama this year.”
But, he adds, tobacco budworms have been replaced in some fields in some areas of Alabama. “Some farmers have fought fall armyworms at economic levels every day since July 15, and they have spent a ton of money,” he says.
With the trials this year, Smith says he was not going to trigger a treatment on plant bugs, and he was not going to trigger on aphids, until July 20.
“When I went out on July 20, I was prepared to go with an automatic pyrethroid spray, and I couldn’t find any worms, so I postponed the treatment for a week. When I came back a week later, we had suffered a lot of bug damage.
“The one lesson we learned this year is if you don’t go with an automatic treatment, and you postpone all of your bug cleanups until July 20, you really can’t let it go any longer. If you don’t have to trigger on worms by July 20, you can’t just keep letting plant bugs and stink bugs build in the cotton. That’s my cleanup date, worms or no worms, from now on,” he says.
Smith said in mid-September that he had made three sprays on the Bt technology varieties and four on the other varieties. The three sprays on the Bt varieties were for bugs with just a pyrethroid, costing $12 to $15 for the chemicals only. On conventional cotton with no Bt technology, he had made three pyrethroid sprays and on Steward application as insurance against tobacco budworms or fall armyworms.
“We spent about $28 treating the conventional cotton,” says Smith. “You can still find some worm damage there, but nothing to get concerned about. I was pleased that we were able to do it this year for that amount of money. I don’t think we can do it for that every year. The proof of the pudding will be in the yields, when we factor in all of the costs of technology, insect control and weed control.”
For the current production year, most Alabama producers have been very successful with a minimal amount of insect control, he says. “I think we’re pretty much over the hump with cotton insects,” he says. “If you still have quarter-diameter bolls that you hope to harvest or late-maturing cotton, you still have to be concerned about stink bugs. We do have a lot of stink bugs this year. A lot of them are brown stink bugs, which means you either have to switch to a phosphate chemistry like Bidrin, or you have to go to a maximum rate of a labeled rate of a pyrethroid in order to get good suppression of the brown species of stink bug.”
Much of Alabama’s cotton crop, says Smith, is too mature to be infested much by any kind of caterpillar pests.