Dr. William S. Gazaway, Extension Plant Pathologist, 104 Extension Hall, Auburn University, Auburn, AL 36849-5624, Phone (334) 844-5505, FAX (334) 844-4072
email: wgazaway@acesag.auburn.edu
Major Nematode Species: Reniform and root-knot nematodes continue to be major problems in all cotton producing areas in the state. Reniform nematodes are the biggest threat, particularly in central and south Alabama. No new nematode infestations were found in 1998, according to soil samples submitted to the Plant Diagnostic Laboratory. Nematode populations in north Alabama were generally low as a result of the extremely dry weather. (For more information, Click on Understanding Cotton Nematodes ... Their Distributions and Densities).
Other Nematode Species: Six other nematode species are present in Alabama -- lesion, stubby root, dagger, ring, stunt, and lance.
These were first reported in 1990 - 1992 survey data. Columbia lance nematodes were first discovered in Autauga county in the central part of the state in 1992. Columbia lance are a much more serious threat to cotton than other lance nematode species found in the southeast and the Mississippi Delta. No new infestations of this species have been found in the state in recent survey activities.
1998 Yield Loss Estimate valued at $390/Bale: 8% of the cotton crop was lost to nematode damage ... 36,020 bales ... valued at $14,047,800.
Seven-year Average Yield Loss Estimate from 1992 through 1998: Annual average of 6.3% of the crop was lost to nematode damage ... 38,838 bales ... valued at $14,047,800.
1999 Activities to Consider: September and October are the best times to take soil samples for reniform nematodes. However, soil analysis can be made from mid-June during early to mid-bloom, right through to the first hard freeze in acreage that has not been previously disturbed.
In-furrow applications of Temik 15G (5 to 7 lb/acre) continue to be the most used nematicide ... and the most effective short term treatment for nematodes in cotton. Telone II, a pre-plant fumigant, is used in a few acres of cotton in south Alabama. A few growers use crop rotation to successfully control nematodes. Our control recommendations continue to stress the importance of sanitation to keep from moving reniform nematodes to new locations. This has had limited success. Nematicides remain the most effective treatment in managing moderate reniform nematode populations.
1998 Research Activity: Two crop rotation schemes were studied for their impacts on reniform populations in cotton.
For details of test results, contact Jennifer Gimpert.