Author
Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/27/2005 Publication Date: 8/8/2006 Citation: Timper, P., Davis, R.F., Tillman, P.G. 2006. Reproduction of Meloidogyne incognita on winter cover crops used in cotton production. Journal of Nematology. 38(1):83-89. Interpretive Summary: Substantial reproduction of the southern root-knot nematode on winter cover crops may lead to damaging populations in a subsequent cotton crop. The amount of population increase during the winter will depend on soil temperature and how good of a host the cover crop is for this nematode. Our objectives were to quantify reproduction of the southern root-knot nematode on rye and various vetch and clover cover crops, and to determine if these cover crops increase population densities of the nematode and subsequent damage to cotton. The cover crops tested were ‘Bigbee’ berseem clover, ‘Paradana’ balansa clover, ‘AU Sunrise’ and ‘Dixie’ crimson clover, ‘Cherokee’ red clover, common hairy vetch and ‘AU Early Cover’ hairy vetch, ‘Cahaba White’ vetch, and ‘Wrens Abruzzi’ rye. Nematode egg production was greatest on berseem clover, Dixie crimson clover, and AU Early Cover and common hairy vetch; intermediate on Balansa clover and AU Sunrise crimson clover; and least on rye, Cahaba White vetch, and Cherokee red clover. In both 2002 and 2003, enough heat units were accumulated between 1 January and 20 May for the nematode to complete two generations. Both AU Early Cover and common hairy vetch led to greater root galling than fallow in the subsequent cotton crop and they also supported high reproduction of the southern root-knot nematode in the greenhouse. Rye and Cahaba White vetch did not increase root galling on cotton and they were relatively poor hosts for the nematode. Only those vetches and clovers that increased populations of root-knot nematode reduced cotton yield. In the southern United States, root-knot nematodes can complete one to two generations on a susceptible winter cover crop, so cover crops that support high nematode reproduction may lead to damage and yield losses in the following cotton crop. Planting rye or a nematode-resistant vetch or clover will lower the risk of building up damaging populations of this nematode compared to more susceptible winter cover crops. Technical Abstract: Substantial reproduction of Meloidogyne incognita on winter cover crops may lead to damaging populations in a subsequent cotton (Gossypium hirsutum) crop. The amount of population increase during the winter will depend on soil temperature and how good of a host the cover crop is for M. incognita. Our objectives were to quantify M. incognita race 3 reproduction on rye (Secale cereale) and various leguminous cover crops, and to determine if these cover crops increase population densities of M. incognita and subsequent damage to cotton. The cover crops tested were ‘Bigbee’ berseem clover (Trifolium alexandrinum), ‘Paradana’ balansa clover (T. balansae), ‘AU Sunrise’ and ‘Dixie’ crimson clover (T. incarnatum), ‘Cherokee’ red clover (T. pratense), common hairy vetch and ‘AU Early Cover’ hairy vetch (Vicia villosa), ‘Cahaba White’ vetch (V. sativa), and ‘Wrens Abruzzi’ rye. Egg production was greatest on berseem clover, Dixie crimson clover, and AU Early Cover and common hairy vetch; intermediate on Balansa clover and AU Sunrise crimson clover; and least on rye, Cahaba White vetch, and Cherokee red clover. In both 2002 and 2003, enough heat units were accumulated between 1 January and 20 May for the nematode to complete two generations. Both AU Early Cover and common hairy vetch led to greater root galling than fallow in the subsequent cotton crop and they also supported high reproduction of M. incognita in the greenhouse. Rye and Cahaba White vetch did not increase root galling on cotton and they were relatively poor hosts for M. incognita. Only those legumes that increased populations of M. incognita reduced cotton yield. In the southern United States, M. incognita can complete one to two generations on a susceptible winter cover crop, so cover crops that support high nematode reproduction may lead to damage and yield losses in the following cotton crop. Planting rye or Meloidogyne-resistant legumes as winter cover crops will lower the risk of building up damaging populations of this nematode compared to most vetches and clovers. |