Cotton Farming

Graduate of University of Florida
Currently associate professor and Extension specialist at the University of Georgia Department of Plant Pathology, stationed at the Coastal Plain Experiment Station in Tifton, Ga.
Current crop responsibilities include cotton, soybeans and corn.

As an Extension plant pathologist for the University of Georgia, I believe that nematodes are one of the most under-managed pests of cotton – not only in Georgia, but across much of the Cotton Belt. Southern root-knot, reniform, Columbia lance and sting nematodes cost cotton producers in the United States millions of dollars each year, both in terms of management expenses and lost yield.

Many ask, “If nematodes on cotton are such an important problem, why are they an under-managed problem?” I am certain that if nematodes were as big as stinkbugs or glyphosate-resistant pigweed, few producers would be able to ignore these “invisible” worms. You cannot see nematodes without aid of a microscope; poor growth and premature cutout they cause in a field can be confused with other problems like drought stress, pH, soil fertility issues and herbicide injury. I cringe when troubleshooting patches of stunted growth in a field and the producer speaks in frustration about “sorry dirt.” As often as not, there is little “sorry” about the soil other than the nematodes that have taken up residence there.

As this issue of Cotton Farming magazine arrives, many cotton producers will have just finished their harvest and few want to think about nematode management for the 2008 season. However, there are decisions and considerations to be made well before next year's seed is planted to maximize protection and to minimize losses to nematodes.

Nematode sampling: The best way to determine the extent of a problem with nematodes in a field is to collect soil samples at harvest from the root-zone of the cotton plants. The samples should be collected before soil becomes too cold and submitted as directed to a nematode diagnostic lab. The results from soil sampling will help the producer understand which nematodes infest the field and how serious the problem is.

Crop rotation: Rotation of crops planted in a field is the cornerstone of effective nematode management. No other tool provides the same level of protection from high populations of nematodes as rotation with non-host crops, though growers wait hopefully for a variety resistant to nematodes. In the southeast, peanut is an excellent rotation crop with cotton; corn effectively reduces reniform nematodes but not southern root-knot nematodes.

Choice of nematicides: Use of nematicides is a popular and effective option for many cotton producers who battle nematodes. Over the past 30 years, use of the granular product aldicarb (Temik 15G) was widespread among cotton producers and was supplemented by the foliar application of oxamyl (Vydate C-LV) in some cases. Producers with high levels of nematodes in a field may use the fumigant 1,3-dichloropropene, (Telone II) for enhanced protection. In 2006, a seed treatment with nematicidal properties, Avicta Complete Pak, burst onto the cotton scene with an aggressive and effective marketing campaign. This product was readily adopted by many producers because of the convenience offered by a seed treatment. Avicta Complete Pak was joined in the market by Aeris Seed-Applied System in 2007.

Because many producers must make their choices of nematicide at the time they order seeds for next season, it has become increasingly important to carefully consider the potential risks and benefits for specific nematicides now rather than later.

Products such as Avicta Complete Pak and Aeris Seed-Applied System are for use in fields with low-to-moderate populations of nematodes. They will not provide adequate protection in fields with more damaging levels of nematodes. As a producer considers use of a nematicide seed treatment, he should consult his Extension service for data that compares the effectiveness of each seed treatment to the effectiveness of Temik 15G. Some may be willing to switch from use of Temik to a seed treatment based simply on the “convenience factor.” I would strongly advise producers to include available efficacy data and soil sampling results in the decision process to insure success throughout the season.

It will be another six months before producers call me to their fields complaining about “sorry dirt” or seeking advice about stunted plants. They can help avoid my visits by carefully planning their nematode management strategies now. The components of the successful strategy include sampling, crop rotation and the careful study and selection of nematicide options.

Contact Bob Kemerait at 229-386 in Tifton, Ga., or at kemerait@uga.edu via e-mail.

- VIEWPOINT - It Takes A Plan To Fight Nematodes
By By Bob Kemerait Tifton, Ga .
Graduate of University of Florida Currently associate professor and Extension specialist at the University of Georgia Department of Plant Pathology, stationed at the Coastal Plain Experiment Station in Tifton, Ga. Current crop responsibilities include cotton, soybeans and corn. As an Extension plant pathologist for the University of Georgia, I believe that nematodes are one of the most under-managed pests of cotton – not only in Georgia, but across much of the Cotton Belt. Southern root-knot, reniform, Columbia lance and sting nematodes cost cotton producers in the United States millions of dollars each year, both in terms of management expenses and lost yield. Many ask, “If nematodes on cotton are such an important problem, why are they an under-managed problem?” I am certain that if nematodes were as big as stinkbugs or glyphosate-resistant pigweed, few producers would be able to ignore these “invisible” worms. You cannot see nematodes without aid of a microscope; poor growth and premature cutout they cause in a field can be confused with other problems like drought stress, pH, soil fertility issues and herbicide injury. I cringe when troubleshooting patches of stunted growth in a field and the producer speaks in frustration about “sorry dirt.” As often as not, there is little “sorry” about the soil other than the nematodes that have taken up residence there. As this issue of Cotton Farming magazine arrives, many cotton producers will have just finished their harvest and few want to think about nematode management for the 2008 season. However, there are decisions and considerations to be made well before next year's seed is planted to maximize protection and to minimize losses to nematodes. *Nematode sampling: The best way to determine the extent of a problem with nematodes in a field is to collect soil samples at harvest from the root-zone of the cotton plants. The samples should be collected before soil becomes too cold and submitted as directed to a nematode diagnostic lab. The results from soil sampling will help the producer understand which nematodes infest the field and how serious the problem is. Crop rotation: Rotation of crops planted in a field is the cornerstone of effective nematode management. No other tool provides the same level of protection from high populations of nematodes as rotation with non-host crops, though growers wait hopefully for a variety resistant to nematodes. In the southeast, peanut is an excellent rotation crop with cotton; corn effectively reduces reniform nematodes but not southern root-knot nematodes. Choice of nematicides: Use of nematicides is a popular and effective option for many cotton producers who battle nematodes. Over the past 30 years, use of the granular product aldicarb (Temik 15G) was widespread among cotton producers and was supplemented by the foliar application of oxamyl (Vydate C-LV) in some cases. Producers with high levels of nematodes in a field may use the fumigant 1,3-dichloropropene, (Telone II) for enhanced protection. In 2006, a seed treatment with nematicidal properties, Avicta Complete Pak, burst onto the cotton scene with an aggressive and effective marketing campaign. This product was readily adopted by many producers because of the convenience offered by a seed treatment. Avicta Complete Pak was joined in the market by Aeris Seed-Applied System in 2007. Because many producers must make their choices of nematicide at the time they order seeds for next season, it has become increasingly important to carefully consider the potential risks and benefits for specific nematicides now rather than later. Products such as Avicta Complete Pak and Aeris Seed-Applied System are for use in fields with low-to-moderate populations of nematodes. They will not provide adequate protection in fields with more damaging levels of nematodes. As a producer considers use of a nematicide seed treatment, he should consult his Extension service for data that compares the effectiveness of each seed treatment to the effectiveness of Temik 15G. Some may be willing to switch from use of Temik to a seed treatment based simply on the “convenience factor.” I would strongly advise producers to include available efficacy data and soil sampling results in the decision process to insure success throughout the season. It will be another six months before producers call me to their fields complaining about “sorry dirt” or seeking advice about stunted plants. They can help avoid my visits by carefully planning their nematode management strategies now. The components of the successful strategy include sampling, crop rotation and the careful study and selection of nematicide options. Contact Bob Kemerait at 229-386 in Tifton, Ga., or at kemerait@uga.edu via e-mail.*

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