Ralph Bagwell was hoping for an “easy” pest year, but it doesn't look like it'll shape up that way. Thus far, says the Louisiana Extension entomologist, “it's looking like it'll be a buggy year. I hate to see that — especially with the price of most commodities.”
In terms of primary cotton pests, bollworm species are potentially worrisome in the state, says Bagwell. Overwintering bollworms emerged in the state some two weeks earlier than normal. Until very recently, conditions have been very conducive to population development, “so we're keeping an eye on that.”
As a result of these things, Bagwell anticipates seeing high bollworm populations in cotton. Already, he's seeing high populations in corn.
“This is a statewide problem. With the worms, if you're getting them at one locale it's safe to assume they're all over. Most likely, in this case, what's true for Winnsboro, La., is also true for Tunica, Miss., and Clarkdale, Ark. The prevailing conditions for the Delta were more conducive to earlier emergence of adults from overwintering and they've taken advantage of that. There's no way to know exactly why they're appearing in such numbers at such an early date, though.”
As with its immediate neighbor to the north, the stinkbug situation in Louisiana is also shaping up to be a major worry, says Bagwell.
Stinkbug populations are abnormally high. Unlike Arkansas, however, Louisiana isn't seeing high numbers of stinkbugs in wheat.
“We're seeing stinkbugs in corn. Some corn has already been sprayed, and I anticipate (that during the first couple of weeks in May) we'll see a lot more being treated.”
The state has a higher percentage of brown stinkbugs than green stinkbugs, says Bagwell, and that portends problems. “The bottom line is we have nothing that's terribly effective on stinkbugs. And, as far as I know, there's nothing in the research pipeline that's going to be any better than what's currently available. The browns are the most difficult to deal with and in combating those, we're almost limited to a couple of organophosphates.”
Bagwell says the Delta is going through a “transition of pests. If you look at Louisiana or anywhere else in cotton-producing country — pre-boll weevil eradication and Bt cotton — we've not had a stinkbug situation to worry about. With all the other sprays, we were getting collateral control.”
But when you add in boll weevil eradication and Bt cotton, farmers are left with a less-sprayed environment. As a result, stinkbug populations are beginning to flourish. The unforeseen rise in stinkbug numbers has caught everyone a bit off-guard, says Bagwell. That's one reason there aren't more products to combat the pest.
“This problem with stinkbugs is a relatively recent development. Chemical companies are looking at 10 or 15 years to develop a compound before it ever reaches the farm. Additionally, you have issues of huge production and developmental costs. When those costs are in the millions of dollars, the market must be there to justify and return such costs. And, in truth, there aren't that many insects out there that can justify those research costs.”
Thrips have also been seen in high numbers in Louisiana cotton fields, says Bagwell. “The deal with thrips is a bit different because we've planted a lot of wheat and it's drying down. It's been three weeks since we've gotten a significant rain and the grasses are all drying down. As a result, numbers of thrips in cotton are high simply because the alternate hosts are drying out and they're moving into green fields.”
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