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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #259377
Title: Response of root-knot nematodes and Palmer amaranth to tillage and rye green manure

Author
item Timper, Patricia - Patty
item Davis, Richard
item Webster, Theodore
item BRENNEMAN, T.B. - University Of Georgia
item Meyer, Susan
item Zasada, Inga
item CAI, G. - University Of Maryland
item Rice, Clifford

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/27/2010
Publication Date: 5/15/2011
Citation: Timper, P., Davis, R.F., Webster, T.M., Brenneman, T., Meyer, S.L., Zasada, I.A., Cai, G., Rice, C. 2011. Response of root-knot nematodes and Palmer amaranth to tillage and rye green manure. Agronomy Journal. 103(3):813-821.

Interpretive Summary: Rye is a frequently used winter cover crop in many agronomic production systems in the USA. Our objective was to determine whether incorporating rye into soil while still green results in greater suppression of root-knot nematodes and the weed Palmer amaranth compared to conventional cover crop management. Two similar experiments were conducted: one with peanut and the other with cotton. The tillage treatments were conventional tillage, green manure, and strip tillage. The cover crop treatments were a weedy fallow and the rye cultivars Wrens Abruzzi, Wheeler, Oklon, and Elbon. Wrens Abruzzi produced the greatest amount of biomass, Oklon and Elbon intermediate, and Wheeler the least. Where there was substantial soil disturbance (e.g., conventional tillage and green manure), Palmer amaranth densities were low and not influenced by cover crop. In the strip tillage plots, however, all of the rye cultivars, except Wheeler, reduced establishment of the weed compared to winter fallow. Root galling from nematodes on cotton and peanut was influenced by tillage, but not by rye cover crop. Gall indices on cotton were greater in conventional tillage than in either strip tillage or green manure plots; whereas on peanut, they were greater in the strip tillage than in the conventional tillage or green manure plots. Neither tillage nor cover crop influenced yield except in 2008 in peanut, where yield was lower in strip tillage than in conventional or green manure plots.

Technical Abstract: Rye (Secale cereale L.), which produces bioactive benzoxazinoid compounds, is a frequently used winter cover crop in many agronomic production systems in the USA. Our objective was to determine whether incorporating rye into soil while still green results in greater suppression of root-knot nematodes (Meloidogyne spp.) and Palmer amaranth (Amaranthus palmeri S. Watson) compared to conventional cover crop management. Two similar experiments were conducted: one with peanut and the other with cotton. Both experiments were a split plot design with tillage as the main plot (conventional tillage, green manure, and strip tillage) and cover crop as the subplot. The cover crop treatments were a weedy fallow and the rye cultivars Wrens Abruzzi, Wheeler, Oklon, and Elbon. Wrens Abruzzi produced the greatest amount of biomass, Oklon and Elbon intermediate, and Wheeler the least. In contrast, Wheeler produced the highest tissue concentration of benzoxazinoids followed by Elbon, Oklon, and finally Wrens Abruzzi. However, the total amount of these compounds (g ha-1) in the rye biomass was similar across cultivars, except in the 2008 cotton experiment where Wheeler produced three-fold more benzoxazinoids than the other cultivars. Where there was substantial soil disturbance (e.g., conventional tillage and green manure), Palmer amaranth densities were low and not influenced by cover crop. In the strip tillage plots, however, all of the rye cultivars, except Wheeler, reduced establishment of the weed compared to winter fallow. Root galling from nematodes on cotton and peanut was influenced by tillage, but not by rye cover crop. Gall indices on cotton were greater in conventional tillage than in either strip tillage or green manure plots; whereas on peanut, they were greater in the strip tillage than in the conventional tillage or green manure plots. Neither tillage nor cover crop influenced yield except in 2008 in peanut, where yield was lower in strip tillage than in conventional or green manure plots.