Herbicide Combinations for Preharvest Weed Desiccation in Early Maturing Soybean (Glycine max)

Abstract

Field experiments were conducted at three locations in Mississippi in 1995 and 1996 to evaluate labeled and alternative herbicides and herbicide combinations for weed desiccation prior to soybean harvest. Weeds evaluated included pitted morningglory, hemp sesbania, spotted spurge, common cocklebur, and sicklepod. Soybean yield and harvestable soybean losses were not affected by preharvest herbicide treatments, spray volume, or surfactant concentration. Soybean moisture was most consistently reduced by glufosinate compared to the untreated and other herbicides and herbicide combinations evaluated. Most desiccation treatments at Stoneville and Brooksville resulted in foreign material similar to the weed-free check. Glufosinate at 0.84, 1.1, and 1.4 kg ai/ha desiccated all weeds evaluated 90% or more with no differences among rates. The addition of 3.4 or 6.7 kg ai/ha sodium chlorate to 0.28 kg ai/ha paraquat, 1.1 and 2.2 kg ai/ha glyphosate, or 0.28 and 0.56 kg ai/ha oxyfluorfen increased desiccation of most weeds evaluated, with no difference between sodium chlorate rates. In some instances, reducing application volume from 281 to 94 L/ha improved pitted morningglory desiccation when 0.28 g/ha paraquat was applied alone. There were no differences between 0.25 and 0.50% (v/v) surfactant for most parameters evaluated.