EVALUATION OF WINTER COVER CROPS IN COTTON CROPPING FOR MANAGEMENT OF ROTYLENCHULUS RENIFORMIS
Keywords: avena sativa, a. strigosa, black mustard, black oat, brassica campestris, b. napus, b. napus ssp. biennis, b. nigra, b. rapa, canola, cotton, cover crops, crimson clover, gossypium hirsutum, lolium multiflorum, lupin, lupinus albus, mustard spinach, oat, radish, rape, raphanus sativus, reniform nematode, rotylenchulus reniformis, rye, ryegrass, secale cereale, sinapis alba, subterranean clover, trifolium incarnatum, t. subterraneum, triticum aestivum, vetch, vicia villosa, wheat, white mustard
AbstractThirty-one winter cover crops and varieties were tested for host status to Rotylenchulus reniformis in greenhouse tests, and eight were selected for further microplot and field trials. Greenhouse trials indicated that crimson clover, subterranean clover, and hairy vetch serve as good hosts for R. reniformis. Reproduction factors (Rf) for those crops were 7.2, 2.2, and 3.7, respectively when grown in the greenhouse at an average temperature of 30ºC. 'Licapo' rape, 'Tyfon' mustard spinach, 'Barnapoli' rape, PI2863 and PI4048 canola, produced Rf values of 1.3, 1.1, 1.0, 1.0, and 1.2 as compared to the Rf value of 4.2 on cotton when grown at an average temperature of 21ºC. Varieties of radish, black mustard, white mustard, canola, lupin, ryegrass, wheat, oats, and rye produced Rf values of less than 1 indicating R. reniformis did not reproduce on these hosts. In microplot and field trials, R. reniformis population densities did not increase on crimson clover, subterranean clover, and hairy vetch over the winter months under natural conditions. Aldicarb applied in the seed furrow at cotton planting subsequent to cover crop termination, decreased R. reniformis population densities for 90 days after planting compared to the untreated control. Seed cotton yields were not affected by the cover crop but increased an average of 20% in all plots treated with aldicarb. Although crimson clover, subterranean clover, and hairy vetch were shown to be hosts of R. reniformis in greenhouse tests, the populations did not increase on these cover crops under the natural environmental conditions of the field and microplot tests.