WEED HOSTS FOR <I>ROTYLENCHULUS RENIFORMIS</I> IN COTTON FIELDS ROTATED WITH CORN IN THE SOUTHEAST OF THE UNITED STATES

Abstract

Lawrence, K. S., A. J. Price, G. W. Lawrence, J. R. Jones, and J. R. Akridge. 2008. Weed hosts for Rotylenchulus reniformis in cotton fields rotated with corn in the southeast United States. Nematropica 38:13-22. The reniform nematode (Rotylenchulus reniformis) is the primary economical nematode pest of cotton (Gossypium hirsutum) in the southern states of Alabama, Louisiana, and Mississippi. Corn (Zea mays), a non-host to R. reniformis, is the principal crop rotated with cotton to reduce R. reniformis populations. In recent years, failure to manage the nematode populations have been attributed to non-controlled common weed species growing in fields farmed under the cotton-corn rotation system. The important role played by 43 weed species in sustaining reniform nematode populations in these fields was confirmed in greenhouse, microplot and field experiments. In the greenhouse, the majority of dicotyledonous weed species tested served as hosts for R. reniformis, while the monocots did not. In field microplot studies, individual weed species (Ipomoea hederacea, I. lacunosa, I. purpurea, and Senna obtusifolia) growing in association with corn increased R. reniformis nematode populations. In field trials where corn plots were treated with only a preemergence herbicide, non-controlled weed species sustained R. reniformis populations as compared to the weed-free treatments. Season long weed management during the corn rotation system is an essential agronomic practice to obtain the full benefit of the rotation, and to effectively suppress R. reniformis populations.