Knock Out Nematodes

July 27, 2012 10:16 PM
Knock Out Nematodes

Seed companies fortify cotton’s nematode barrier

You know they are there. You can’t see the nematodes in the soil, but the yield monitor pinpoints their warpath. Early seedling damage from the microscopic wormlike insects injured the roots and they never fully recovered.
More than a year after the halt of Temik insecticide production, there has been more pressure for seed companies to develop cotton products to suppress nematodes.
"You never get rid of nematode populations; once you have them, you always will," says Gary Lawrence, Mississippi State University nematologist.
"Several years ago, we surveyed Mississippi for the presence of nematodes and found reniform nematodes were infesting 32% of the state and root knot nematodes were infesting about 12.5% of the state," he adds.
"In my research, using small acreage control plots, I would try to determine the maximum yield loss from nematodes. In these studies, I would get 19% to 27% yield losses," Lawrence says. "I was looking at the worst-case scenario to see if these nematode control products would actually benefit the farmer and increase yields."
Mississippi isn’t alone. The National Cotton Council (NCC) tracks yield losses from nematodes, as well as areas of infestation. In 2011, cotton growers lost 3.8% of yield due to nematodes, which accounts for 40% of the total loss from all diseases and nematodes in the Cotton Belt, says Don Blasingame, NCC’s coordinator for the Beltwide Nematode Survey and Education Program.
States that report the most loss from nematodes include Alabama, Georgia, Louisiana, Mississippi and Virginia.
Nematodes have always been an issue, says Kirby Lewis, a Shallowater, Texas, cotton grower. "It’s just that now we’ve become more aware of the problem. Input costs are so high now—anything that affects yield is taken note of.
"We were used to having a bale to an acre yield. Now if you don’t do at least two or two-and-a-half to an acre, it’s devastating," he adds.

In the genetics. Breeders know that there is a lot at stake. "I want growers to focus on maximizing yield potential and not have to worry about having nematodes. They have enough other concerns with prices and weather," says Roy Cantrell, Monsanto lead for cotton breeding.
"The breeding and germplasm within Deltapine focuses on developing highly resistant germplasm for the Delta, southeast U.S. and Texas. For existing products that are on the market, we have Deltapine 174 RF, which offers moderate resistance to root knot nematodes," he adds.
"However, what we are doing now is different. We are developing the next generation of genetic resistance to nematodes by breeding," he says.
Using DNA markers, molecular breeding and the genetics of resistance, the new products from Deltapine will be quite distinct from the varieties available now. These products are currently in the pipeline and will be released mid-decade, Cantrell says.
"We’re trying to protect the genetic potential that’s in the seed and breed for the highest-yielding cotton varieties," he explains. "We develop germplasm and use markers to find the genes with the highest resistance to nematodes and put them in the Deltapine varieties. Growers want cotton to perform in fields where there are nematodes and still yield with the best fiber quality.
"We see the real future being strong genetic resistance in the variety, combined with the best seed treatment technology for systems to get the best protection from nematodes as Temik is phased out," Cantrell says.
"Based on reproduction cycles, root knot populations explode midseason, and by harvest there is no difference between treated and untreated areas," he says. "With genetic resistance, you can suppress throughout the life cycle. That, combined with seed treatments, is a very effective system. Particularly in continuous cotton or if you are growing a host that is susceptible after cotton, you are suppressing the nematode pressure in the soil in a way that you aren’t with chemical control."
The challenge is that the nature of nematodes doesn’t make it easy.
Root knot nematodes typically exist in non-uniform patterns across fields and are often found concentrated in hot spots. This means you have to look at all areas of the field.
"When you add a seed treatment to all of your seed and you have a variety that has nematode tolerance, you want to plant this combination across the field to combat yield loss due to nematodes," explains Jeff Brehmer, Bayer CropScience’s U.S. marketing manager for FiberMax and Stoneville cotton.
"Bayer CropScience released a variety in 2011 named FM 2011GT and early data indicate potential for root knot nematode tolerance. We are making plans to have that variety available in much larger supply in 2013," he says.
Two varieties Bayer has set for 2013 launch will stack LibertyLink and GlyTol technology, as well as tolerance to root knot nematodes.
This year, Bayer combined Aeris insecticide with the seed treatment Poncho/VOTiVO to give farmers even more options. "Aeris insecticide has been applied on cottonseed over the past several years with very good thrips control," Brehmer says. "Good thrips control lends itself to overall plant health. If a variety has root knot nematode tolerance, plus you’re using Aeris, you’re managing your cotton crop to get a successful start and effectively compete with nematodes."
Poncho/VOTiVO, a popular seed treatment combination used in corn, was introduced on FiberMax and Stoneville cotton seed in combination with Aeris in 2012 as a factory seed treatment. Availability in 2013 is to be determined. "We’re still evaluating it, but we’re seeing some good results and we just want to quantify yield at harvest this fall," Brehmer says. "This year was the first year for Poncho/VOTiVO in cotton, and when we combine that with Aeris we are getting even better nematode control than with Aeris alone.
"Today we’ve got additional varieties with root knot nematode tolerance, but at Bayer CropScience we are continuing to seek traits that can be identified in our germplasm pool, using molecular markers and the latest advanced technologies in cotton breeding to identify new means of nematode tolerance," he adds.

Know what’s below. No matter what genetics are going in the ground, it pays to know what your crop is up against. Not all cotton fields have nematode pressure, and it’s important to get the right product and management in each field.
"Producers should pull nematode samples so that they know what’s in the soil. If there are high levels of reniform or root knot, the farmer may want to rotate crops, because the seed treatment is really the only tool that he can use to get good control," Lawrence says.

Temik—No, It’s Meymik

Cotton producers lamenting the loss of Temik won’t have to wait much longer for another chance at using aldicarb to alleviate early-season nematode and insect pressure. Receiving its clearance from the Environmental Protection Agency (EPA) in December 2011, Meymik, from AgLogic Chemical LLC and marketed by MEY Corporation, puts one more option in the nematode toolbox.
"It’s taken more than six years to get the EPA registration," says Antoine Puech, managing partner of AgLogic Chemical. "We were restricted on how much we could say or do until we got the registration. We received EPA registration in December; now we are racing against time to produce finished goods in time for the 2013 season.
"This product is very similar to Temik. We’ve tested it through application equipment where it performed like Temik, and its aldicarb chemical composition is virtually identical. So we feel good that users will get the same results and experience using this product," Puech says.
The registration includes application for cotton, peanuts, soybeans, dry beans, sugar beets and sweet potatoes.
"There is very strong support from grower organizations, the National Cotton Council, Cotton Incorporated, and university and Extension cotton researchers for this product. We feel confident that it will perform identically to Temik, because they both have the same active ingredient and type and size of granules," Puech says.
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Steps for Developing a Nematode Management Program:

1. Sample field(s) to determine if nematodes are present; if so, establish population density levels. If NO species are detected, the strategy is to make sure none are introduced.
2. If nematodes are present, the strategy is to keep them from spreading to non-infested fields and to reduce population densities.
3. Effective management practices require knowing which field(s) is/are infested, genera present, and population densities. Lance nematodes should be identified by specific species.
4. Develop a Nematode Management Program well in advance of planting. (For more information, see Nematode Soil Sampling).
5. Review analysis of soil samples taken last fall to identify nematode species, their locations, and their densities.
6. Review nematode control options — cultural and chemical practices — that are available/practical in your situation.
7. Design and follow a strategy that suits your special situation. Consider factors such as history of cropping patterns, soil types, single/multiple nematode species present, and weather anticipated.


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