Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 10, 1999
Publication Date: N/A
Interpretive Summary: Root-knot nematodes are major pests on many crops produced in the southeastern United States. Corn is used in rotation with many crops. Commercial corn cultivars currently available are not resistant to root- knot nematodes. The efficacy of a double-cross corn hybrid (resistant to root-knot nematodes) and a nematicide for management of root-knot nematodes sin a corn-squash rotation was evaluated in field tests during 1996 and 1997. The resistant corn hybrid proved beneficial in suppressing numbers of root-knot nematodes in the soil and root damage in the following squash crop compared to a commercial cultivar. The disadvantages of the resistant hybrid include excessive lodging and low yield (57% as much as the commercial cultivar). The application of a nematicide increased yield of both corn entries 4% to 6% over the untreated controls. The development of resistant corn cultivars with desirable agronomic characteristics and greater yield potential will be useful in the management of root-knot nematode populations under various cropping systems in different geographical areas.
Technical Abstract: The efficacy of a double cross corn (Zea mays L.) hybrid (Old Raccoon selection X T216) X (Tebeau selection X Mp 307) resistant to Meloidogyne incognita as a rotational crop, and fenamiphos for management of root-knot nematode (M. incognita race 1) in squash (Cucurbita pepo var. melopepo (L.) Alef.) was evaluated in field tests during 1996 and 1997. Numbers of M. incognita in the soil and root-gall indices were lower on the resistant hybrid than on a commercial cultivar DeKalb DK-683. Treatment means across both corn entries had lower root-gall indices from fenamiphos treatment than untreated controls. In soil collected 2 September 1997, there were more colony forming units (cfu) per gram of oven-dried soil of Pythium spp. from plots planted to DK-683 treated with fenamiphos than in untreated plots (88 vs. 59 cfu). Some plots of corn had individual plants with 10% to 15% of the crown and brace roots decayed, but there were no differences among soil chemical treatments. Lodging of stalks was 40% to 50% more in double cross hybrid than in DK-683. Yield was greater from DK-683 than the double cross hybrid. Root-gall indices and yield of squash were significantly lower following the double cross hybrid than DK-683 and in fenamiphos-treated plots than in untreated plots of squash. Yield of squash was not affected by fenamiphos at-planting treatment on the preceding crops of corn. Nematode resistance must be transferred into the elite materials of commercial seed companies to reach its full potential as a nematode management strategy.