Evaluation of winter cover crops in cotton cropping for management of Rotylenchulus reniformis.
Thirty-one winter cover crops and cultivars were tested for their suitability as host of R. reniformis in greenhouse and field tests carried out in Alabama, USA. Greenhouse tests showed that crimson clover, subterranean clover and hairy vetch were good hosts for R. reniformis, with reproduction factors of 7.2, 2.2 and 3.7, respectively, when grown at an average temperature of 30°C. Rape cv. Licapo, mustard spinach cv. Tyfon, rape cv. Barnapoli, canola lines PI2863 and PI1408 recorded Rf values of 1.3, 1.1, 1.0, 1.0 and 1.2, respectively. Cultivars of radish, black mustard, white mustard, canola, lupin, ryegrass, wheat, wheat, oats and rye produced Rf values of less than 1, indicating that the parasitic nematode did not produce in these hosts. In microplots and field trials, R. reniformis population density did not increase in crimson clover, subterranean clover and hairy vetch during the winter and under natural conditions. Aldicarb applied in seed furrow at cotton planting subsequent to cover crop termination reduced the R. reniformis population density for 90 days after planting compared to the control. Seed cotton yields were not affected by the cover crop but increased an average of 20% in all plots treated with aldicarb.