Cotton Farming

Innovations by cotton breeders across the Cotton Belt may soon have producers selecting varieties based on season-long resistance to the root-knot nematode.

This development will expand the portfolio of tools available to control the pest.

To date, ST 5599BR is the only commercially-available cottonseed variety that shows moderate resistance to root-knot nematodes, says Terry Kirkpatrick, University of Arkansas Extension plant pathologist.

Kirkpatrick says it is important for cotton producers to understand the difference between nematode tolerance and resistance.

“From a nematology standpoint, we define tolerance by growing two varieties under equivalent nematode pressure,” he says. “Under this circumstance, the cultivar to suffer less yield suppression to nematodes is actually deemed tolerant.”

Whereas, Kirkpatrick defines resistance of a cotton variety by its ability to perform well in the presence of nematodes while also inhibiting the performance of nematodes.

Potential Resistant Varieties

Development of additional cotton varieties with resistance to root-knot nematode is on the horizon. At PhytoGen, Mustafa McPherson, cotton breeder, is reviewing the performance of experimental lines derived from crossing the WideStrike Insect Protection and Roundup Ready Flex traits into an early maturity strain, 99M-548, with moderate root-knot nematode resistance.

While additional trials will evaluate the performance of 99M-548 WRF in 2007, these results look promising.

In addition to the latest development from PhytoGen, Bob Kemerait, University of Georgia Extension specialist and associate professor, says Delta and Pine Land Company is testing a group of varieties. The standard for measurement in these trials is the comparison of the lint yield results of these varieties versus ST 5599BR.

Control Recommendations

The products currently under evaluation in trials include Telone soil fumigant, seed treatments Avicta Complete Pak and Aeris seed-applied system, and Temik pesticide and Vydate insecticide/nematicide.

“The amount of cotton acreage planted with cottonseed treated with a seed treatment in 2006 caught me a little by surprise,” Kemerait says.

“Cotton producers like the convenience of a seed treatment, but they should be asking themselves if it provides the level of protection they need for their situation,” he adds.

To assess the effectiveness of a seed treatment, Kirkpatrick recommends looking at fields on an individual basis.

“Know the performance history of each field, soil types, and review yield maps if they’re available,” he says.

Kirkpatrick also suggests that farmers “look to information from a nematode sample to help guide the decision for what treatment to use.”

Kemerait concludes, “Producers continue to hear about developments in this arena, but nothing has materialized. While they wait for a variety, it’s exciting to see the number of tools to control nematodes growing.”

Bader-Rutter, which represents Dow AgroSciences, provided information for this article.

Use Different Approach To Control Nematodes

Innovations by cotton breeders across the Cotton Belt may soon have producers selecting varieties based on season-long resistance to the root-knot nematode. This development will expand the portfolio of tools available to control the pest. To date, ST 5599BR is the only commercially-available cottonseed variety that shows moderate resistance to root-knot nematodes, says Terry Kirkpatrick, University of Arkansas Extension plant pathologist. Kirkpatrick says it is important for cotton producers to understand the difference between nematode tolerance and resistance. “From a nematology standpoint, we define tolerance by growing two varieties under equivalent nematode pressure,” he says. “Under this circumstance, the cultivar to suffer less yield suppression to nematodes is actually deemed tolerant.” Whereas, Kirkpatrick defines resistance of a cotton variety by its ability to perform well in the presence of nematodes while also inhibiting the performance of nematodes. Potential Resistant Varieties Development of additional cotton varieties with resistance to root-knot nematode is on the horizon. At PhytoGen, Mustafa McPherson, cotton breeder, is reviewing the performance of experimental lines derived from crossing the WideStrike Insect Protection and Roundup Ready Flex traits into an early maturity strain, 99M-548, with moderate root-knot nematode resistance. While additional trials will evaluate the performance of 99M-548 WRF in 2007, these results look promising. In addition to the latest development from PhytoGen, Bob Kemerait, University of Georgia Extension specialist and associate professor, says Delta and Pine Land Company is testing a group of varieties. The standard for measurement in these trials is the comparison of the lint yield results of these varieties versus ST 5599BR. Control Recommendations The products currently under evaluation in trials include Telone soil fumigant, seed treatments Avicta Complete Pak and Aeris seed-applied system, and Temik pesticide and Vydate insecticide/nematicide. “The amount of cotton acreage planted with cottonseed treated with a seed treatment in 2006 caught me a little by surprise,” Kemerait says. “Cotton producers like the convenience of a seed treatment, but they should be asking themselves if it provides the level of protection they need for their situation,” he adds. To assess the effectiveness of a seed treatment, Kirkpatrick recommends looking at fields on an individual basis. “Know the performance history of each field, soil types, and review yield maps if they’re available,” he says. Kirkpatrick also suggests that farmers “look to information from a nematode sample to help guide the decision for what treatment to use.” Kemerait concludes, “Producers continue to hear about developments in this arena, but nothing has materialized. While they wait for a variety, it’s exciting to see the number of tools to control nematodes growing.” Bader-Rutter, which represents Dow AgroSciences, provided information for this article.

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