No one knows more about reniform nematodes than Bill Gazaway. Working on a shoe-string research budget for the past 15 years, Gazaway, now a retired Alabama Extension plant pathologist, has scrutinized them under microscopes and plotted their course through hundreds of fields throughout Alabama.
But despite all he knows about nematodes, Gazaway, who is still involved in on-going efforts to combat nematodes despite his retirement, is the first to concede that these microscopic organisms are beyond the ability of one individual to control. Indeed, reniform nematodes, he believes, represent one of the single biggest threats to Southeast cotton production — a problem that already is causing losses of roughly $27 million dollars each year in Alabama and millions more throughout the South.
Two things, he believes, are needed to contend with reniform nematodes — better funded research and educational outreach.
“We've got growers going out of business and they don't even know why,” he says. “There is some on-going USDA basic research looking for genetic resistance. And this, if successful, will pay huge dividends 10 to 15 years down the road, but what good is it if we can't keep our growers in business long enough to profit from this research?”
For now, Gazaway says, growers need to be made aware of the reniform nematode problem and how to use current tools available to manage it. And these need to be fine-tuned to meet specific growers' needs, he adds.
“We cannot recommend control measures for reniform problems in cotton for the entire South based on research conducted in one location. Nematicides and crop rotation systems need to be evaluated in several regions of a state and over several states,” Gazaway stresses.
“We need to refine that knowledge to determine the most efficient application rates for nematicides and crop systems for the different soil types and growing conditions throughout the South.”
Case in point: Gazaway and other researchers have shown that a one-year corn and peanut rotation is highly effective in controlling reniform nematodes in Alabama — one reason peanut acreage has exploded recently throughout southwestern Alabama, where nematode pressure is exceptionally strong.
Even so, what works in Alabama may not work in other parts of the South, such as the Mississippi Delta, Louisiana or Arkansas, Gazaway notes.
“Some cotton nematologists in Mississippi say that corn may require two or more seasons to bring reniform down to manageable levels in parts of the Mississippi Delta,” he says. “And I don't know why. It could stem from a difference in reniform populations. Mississippi populations may be more aggressive and capable of producing larger populations than in Alabama.
“Whatever the case, I wouldn't dare recommend a one-year rotation there as we do in Alabama when I don't have the data to support that. With reniform nematodes, you just can't take the cookie cutter approach with all the different growing conditions that exist in the South.”
A recent survey conducted in the Mississippi Delta showed that in Sharkey County, north of Vicksburg, 80 percent of the cotton acreage has a reniform nematode problem. Farther north in Leflore County, 30 to 40 percent of the fields are infested. And in Tunica County, 15 to 20 percent of the fields have reniform nematode problems.
“The same thing that happened in Alabama is happening in Mississippi,” says Gazaway. “The reniform nematode is moving south to north. And it's also moving into Tennessee, where cotton producers have never seen it.”
As Gazaway is the first to concede, fine-tuning and improving the research already in place will cost money. What scientists need, he says, are adequately funded, broad-based rotation studies throughout the region provided through USDA and other public and private sources.
The same goes for nematicide and fumigant application studies, he says.
So far, virtually all of the research into reniform nematodes has been carried out through the Beltwide Research and Education Committee composed of university and Extension cotton nematologists throughout the South working on tight budgets.
“We have the people and infrastructure already in place. What we need now is adequate funding for them to operate,” Gazaway says.
Education is another crucial factor, Gazaway says.
“One of the problems we've encountered is that many companies don't realize how serious this problem is and, consequently, don't have the incentive or the funds to justify developing nematicides just for cotton. It would be very difficult for them to recover their developmental costs with just one crop.”
But this is only part of the challenge, Gazaway says. The other problem is the pell-mell damage associated with reniform nematodes that often lulls producers into complacency.
“I used to scout cotton and I know,” Gazaway says. “Farmers used to call me in the middle of the night when they had a bollworm or tobacco budworm problem. But they could see they had a problem when the squares flared or when worms were feeding on the bolls.
“But you don't see nematodes, and the damage they cause often isn't readily apparent. And therein lies the problem.
“It really is a stealth disease,” he adds. “Some years, it is so frustrating to encounter producers who have treated for reniform nematodes but who don't see obvious results. They say, ‘I put in a whole lot of Temik but didn't see a heck of a lot of difference.'
“That's the problem with this particular pest - there may be some years when reniform nematodes don't cause a lot of damage — especially when growing conditions for cotton are good. But in other years, when cotton is under stress, you're really in for it.”
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