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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #104061
Title: POPULATION DYNAMICS OF MELOIDOGYNE INCOGNITA, M. ARENARIA, AND OTHER NEMATODES AND CROP YIELDS IN ROTATIONS OF COTTON, PEANUT, AND WHEAT UNDER MINIMUM TILLAGE.

Author
item Johnson, Alva
item Dowler, Clyde
item Handoo, Zafar

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Farmers are accepting conservation tillage due to the economics of time, labor and other resources. Farmer experience in the short-term has been generally good. However, there remains concern for the practice over the long-term due to control of perennial weeds and nematodes, and to the supposed inability to get nematicides and plant nutrients into the root zone when they must be applied on the soil surface with minimal opportunit for incorporation. Research on conservation tillage under sprinkler irrigation where nematicides, herbicides and plant nutrients are delivered in irrigation water has been very limited. Wheat (W), cotton (C), and peanut (P) were arranged in three cropping sequences; W-C-W-C, W-P-W-P, and W-P-W-C to determine the effects of a nematicide and cropping sequence on nematode population densities and crop yields under conservation tillage and irrigation for 6 years. Root-knot nematodes did not cause damage to roots of cotton or peanut during the first 3 years but increased on both crops during the last 3 years of the study. Yield of wheat in all cropping sequences tended to be greater in nematicide-treated plots than in untreated plots. Wheat yields were highest in the W-P-W-P, intermediate in the W-P-W-C, and lowest in the W-C-W-C sequence. The nematicide treatment increased yield of cotton over untreated plots 11% in the W-C-W-C sequence compared to only 3% in the W-P-W-C sequence. Generally, the nematicide treatment had no beneficial effect on peanut yield, but yields were 38% higher in the W-P-W-C than in the W-P-W-P sequence. Cotton and peanut production under conservation tillage may have a place for more growers in the southern U.S., and additional improvements in farm chemicals and irrigation application technologies may make it even more practical.

Technical Abstract: Cotton (Gossypium hirsutum) cultivars Georgia King and SureGrow and peanut (Arachis hypogaea) cultivars AgraTech 127 and Andru 93 were grown successfully with little or no suppression in yields caused by nematodes in conservation tillage following wheat harvested for grain. Wheat (W), cotton (C), and peanut (P) were arranged in three cropping sequences; W-C-W-C, W-P-W-P, and W-P-W-C, to determine the effects of fenamiphos and cropping sequence on nematode population densities and crop yields under conservation tillage and irrigation for 6 years. Root-knot nematodes Meloidogyne incognita increased on cotton and M. arenaria on peanut and both species remained in moderate to high numbers in plots of wheat. No galls were observed on cotton or peanut during the first 3 years of the study. Root-gall indices (1 to 5 scale: 1 = 0%, 2 = 1% to 25%, 3 = 26% to 50%, 4 = 51% to 75%, and 5 = 76% to 100% of roots galled) increased more rapidly and to higher levels on cotton (2.89) than peanut (1.23) during th last 3 years of the study, and were not affected by fenamiphos (6.7 kg a.i./ha) treatment or cropping sequences. Generally, yield of wheat in all cropping sequences tended to be greater in fenamiphos-treated plots than in untreated plots. Yields of cotton was greater in fenamiphos-treated plots than in untreated plots in most years. Fenamiphos treatment had no beneficial effect on peanut yield. Peanut yield was 38% higher in the W-P-W-C than in the W-P-W-P sequence. Cotton and peanut production under conservation tillage and irrigation may have a place for more growers in the southern U.S. and additional improvements in farm chemicals and irrigation application technologies may make it even more practical.