Dr. Terry Kirkpatrick, University of Arkansas, SW Research and Extension Center, 362 Highway 174 N., Hope, AR 71801, Phone (870) 777-9702 ext. 111, FAX (870) 777-8441
Major Nematode Species: In Arkansas, cotton is primarily affected by root-knot and reniform nematodes. The four cotton growing areas in the state are: Northeast, Central Delta, Southeast Delta, and Southwest in the Red River Valley.
2001 Nematode Survey
Reniform nematodes have increased dramatically in Arkansas since 1990. Currently, this nematode can be found in about 20% of the cotton fields in the Southeast and Central Delta regions. Greatest incidence of this nematode is in Monroe County in the Central Delta where almost 80% of the samples submitted by growers during the 2000 season contained high levels of reniform nematodes. Reniform nematodes have been documented in 12 major cotton producing counties, including Mississippi and Poinsett counties in the Northeast Delta.
Root-knot nematodes have been found in every county in the state where cotton is produced. The Southeast Delta has the greatest problem with this species, and during the 2000 season, 48% of grower-submitted samples (2,820 total) from this region contained root-knot. The Northeast, Southwest and Central Delta regions also have a significant root-knot incidence with 26, 24, and 18% of samples submitted to the Arkansas Nematode Diagnostic Laboratory containing this nematode species.
Other Nematode Species: No evidence of sting, or Columbia lance nematodes has been found in Arkansas cotton, although sting nematodes have been identified in soybeans in the upper Arkansas River Valley.
1998 Yield Loss Estimate Valued at $390/Bale: 5% of the cotton crop was lost to nematode damage ... 69,767 bales ... valued at $27,209,130.
Seven-year Average Yield Loss Estimate from 1992 through 1998: Annual average of 4.14% of the crop was lost to nematode damage ... 66,887 bales ... valued at $22,731,840.
2002 Activities to Consider in Latter Part of Growing Season: University of Arkansas specialists say the best time to obtain soil samples for nematodes is September - October. This is when nematode populations are at their highest, and the most accurate assessments of infestations are possible.
2000 Research Activity: Field tests (1993-1999) indicate that application of Temik in severe root-knot fields improved lint yields by an average of 109 lb/acre, and in severe reniform nematode fields by 78 lb/acre. With both reniform and root-knot nematodes, application of 5 lb/acre of Temik at planting followed by a sidedress application of an additional 5 lb/acre slightly before pinhead square appears to be the most consistent treatment for nematode suppression. Lint yield improvements with Telone II (2000-2001) at 3 gal/acre averaged 167 lb/acre.
For details of test results, contact Jennifer Gimpert.