SOYBEAN (GLYCINE-MAX) SEED QUALITY AND HARVESTING EFFICIENCY AS AFFECTED BY LOW WEED DENSITIES

With the shift to earlier maturing soybean cultivars, harvest interfer ence data are needed at low weed densities that will not reduce yield, but may affect soybean quality or harvesting efficiency. Field experi ments were conducted in 1995 and 1996 to determine the density of five weeds necessary to warrant desiccation treatments, There were no cons istent differences in losses of harvestable soybean due to weed densit y. Common cocklebur increased foreign material and soybean moisture at a greater rate than did hemp sesbania, ivyleaf morningglory, or redro ot pigweed, with sicklepod intermediate among these species. Soybean t est weight was reduced by 17, 13, and 59 gn, for each plant/meter of r ow with redroot pigweed, sicklepod, and common cocklebur, respectively , whereas hemp sesbania and ivyleaf morningglory did not affect test w eight. However, ail species evaluated increased damaged soybean seeds by 8.2 to 11.1% for each plant/meter of row. combine speed was not aff ected substantially by the weed densities evaluated.