July 17, 2007
Plant bug infestations in some areas of the Mississippi Delta this season are “serious, serious,” says Angus Catchot, Mississippi Extension entomologist.
“One consultant told me, ‘It’s a problem that can’t be fixed with money. We just don’t have enough tools for control,’ he said at the annual meeting of the Mississippi Boll Weevil Management Corporation at Grenada, Miss.
“People are doing things that remind me of the awful 1995 budworm year — they’re rotating chemistry and doing everything they can, and they’re still losing fruit.”
In 1995, Catchot says, “The people who gave up had no cotton to harvest; those who sprayed ended up with a crop of sorts.
“Right now (mid-July), there are places in Washington, Sunflower, Bolivar, and Coahoma counties that have been under intense plant bug pressure since pinhead square. If they get 20 percent fruit retention, they’ll be lucky.
“Normally, it’s late July before we have much of a problem with this pest. This year, some producers have made eight, nine, 10 applications since pinhead square.
“The closest comparison to this situation was in 2004, but the infestations have been sustained much longer this year.”
Almost daily rains the first two weeks of July only exacerbated the problem, Catchot says. “There’s a lot of rank cotton and it’s difficult to get the spray down into the plants — not to mention the problems the aerial applicators have had just trying to get some decent flying conditions between rains.
“It’s not doom and gloom, but growers need to be aware of the potential for problems with this pest.”
Many, he says, have too much invested in the crop to cut back on spray efforts. For them, “it may be necessary to tighten schedules to four to five days, and to get some Pix out to help with the rankness.
“It’s harder for the spray to penetrate a rank canopy, so anything you can do to reduce rankness can help with controlling pests.”
Queried about the rain-fastness of pesticides, Catchot says, “There’s no good solid evidence on this — about all we have to go by is the label information. But no matter what the label says, you need at least six to eight hours after application before another rain. The longer you can have the material on the plants before a rain, the better.”
He says he has noticed that in some of the worst-infested areas, “the cotton that looks best is skip-row, which is probably a function of that spacing allowing better coverage.”
Catchot says some work is also being done with an air-assist spray rig, which uses a 180-mph air blast to push the chemical down into the plants.
Despite the problems growers are having with plant bugs, he says, there’s little promise of relief in terms of new chemistry.
“Plant bugs are mostly a problem in Mississippi, Arkansas, and Louisiana. Growers in those states average $28 to $35 per acre for plant bug control; outside those states, it’s only 5 cents or so. It’s hard to get attention from industry to develop something to deal with a somewhat localized problem.
“But an effective plant bug material is the Holy Grail right now.”
The Environmental Protection Agency shows “nothing in anybody’s pipeline equal to the standard materials we’ve had for years,” Catchot says.
“We can always go to them for an exemption, and we’re going to meet with them this fall to try and make a case for their making additional materials available — but it’s not going to happen this year. So, growers need to rotate available chemistries and increase frequency as the situation warrants.”
Part of the answer, he says, may be in transgenic varieties that offer resistance to plant bugs, “but that’s probably 10 years down the road. Until we can get some relief, either with new chemistry, new varieties, or other methods, we’re just going to have to look at a lot of little things and use them as best we can.”
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