Evaluation of soybean injury from sulfentrazone and inheritance of tolerance

Experiments were conducted in the field and greenhouse to evaluate the effects of cultivar and sulfentrazone rate on soybean injury and yield from soil-applied sulfentrazone and to determine soybean inheritance of sulfentrazone tolerance. Excessive rainfall and cool growing conditions in 1996 enhanced sulfentrazone injury and caused yield reduction iri the susceptible cultivars 'KS4895' and 'Hutcheson' at 0.56 kg ai ha(-1) and KS4895 at 0.42 kg ha(-1). Yields of tolerant cultivars 'Deltapine 3478' and 'Manokin' were not reduced. Sulfentrazone at 0.42 kg ha(-1) reduced soybean stand 17 and 35% for tolerant and susceptible cultivars, respectively. Field and greenhouse inheritance studies were conducted on plant families developed from two crosses: Manokin (tolerant) by 'Asgrow A4715' (susceptible) and 'Northrup King S59-60' (tolerant) by KS4895 (susceptible). The sulfentrazone tolerance of Manokin and Northrup King S59-60 appeared to be controlled by a single gene, with tolerance being dominant to susceptibility. The allelic relationship of tolerance from these two sources needs to be determined.