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LOGO: Journal of Cotton Science


Rye Residue Levels Affect Suppression of the Southern Root-Knot Nematode in Cotton

Authors: Patricia Timper
Pages: 242-246
Plant Pathology and Nematology

In the southeastern U.S., rye (Secale cereale) is frequently planted as a winter cover crop in conservation tillage cotton. Although rye produces toxic benzoxazinoid compounds that might play a role in nematode suppression, it is also a host for the southern root-knot nematode Meloidogyne incognita, a major pathogen of cotton in the U.S. The objective of this study was to determine whether a high-residue rye cover crop would reduce populations of M. incognita compared to fallow soil and the standard rye cover crop. The study was conducted in a field infested with M. incognita. The experiment was repeated four times from 2012 to 2015 and was a randomized complete block design with three cover crop treatments (weedy fallow, standard rye, and high-residue rye), each replicated eight times. At mid-season of the cotton crop, nematode numbers in soil were greatest in the standard rye, lowest in the high-residue rye, and intermediate in the fallow treatment. After cotton harvest, standard rye had greater numbers of nematodes in the soil than the other cover-crop treatments. Root galling caused by M. incognita showed a similar trend as the mid-season numbers with the greatest galling in the standard rye and the lowest galling in the high-residue rye treatment. Planting high-residue rye solely for suppression of M. incognita is probably not economical. However, if farmers plant high-residue rye to improve soil structure, moisture retention, and weed control, then they could benefit also from lower populations of M. incognita.