Vegetable Soybean Tolerance to Bentazon, Fomesafen, Imazamox, Linuron, and Sulfentrazone

Abstract

Poor weed control, resulting from limited herbicide availability and undeveloped integrated weed management systems, is a major hurdle to production of vegetable soybean in the United States. Vegetable soybean, the same species as grain-type soybean, has few registered herbicides because of unknown crop tolerance. Tolerance of as many as 128 vegetable soybean entries to a 2X registered rate of bentazon, fomesafen, imazamox, linuron, and sulfentrazone were quantified within 4 wk after treatment in field trials. Several grain-type soybean entries were included for comparison, including entries with known herbicide tolerance or sensitivity. Injury and seedling growth reduction to all vegetable entries was comparable to all grain-type entries for fomesafen, linuron, and sulfentrazone; and less than all grain-type entries for bentazon and imazamox. Responses of ten of the more widely used vegetable soybean entries were comparable to grain-type entries with known herbicide tolerance. Bentazon, fomesafen, imazamox, linuron, and sulfentrazone pose no greater risk of adverse crop response to vegetable soybean germplasm than the grain-type soybean to which they have been applied for years. Since initiation of this research, fomesafen, imazamox, and linuron are now registered for use on the crop in the United States. Development of integrated weed management systems for vegetable soybean would benefit from additional herbicide registrations.