Tolerance of selected cotton lines to Rotylenchulus reniformis

The reproductive and damage potential of the reniform nematode, Rotylenchul us reniformis, on five cotton breeding. lines reported as tolerant to this nematode in Texas were compared with two standard cotton cultivars, Deltapi ne 50 and Stoneville W 887, in a North Carolina field naturally infested wi th X. reniformis. Numbers of R. reniformis in soil were suppressed at midse ason, and cotton-lint yield was increased by preplant fumigation with 1,3-d ichloropropene. Population densities of R. reniformis at cotton harvest wer e unaffected by fumigation in 1998, but were affected in 1999. Some of the putatively tolerant breeding lines supported lower levels of R. reniformis and had higher tolerance indices to reniform nematode than the standard cul tivars, but the yields of the breeding lines were significantly lower than the standard cultivars. Fumigation resulted in a 100- to 200-kg/ha increase in cotton lint yield for cultivars LA 887 ad Deltapine 50.