ABSTRACT
The evolutionary responses of weeds in soybean production relate mainly to biological features that enable certain species to cause interference with the growth and reproduction of the soybean plant. Interference is the combined effect of competition plus allelopathy. Soybean acreage has grown rapidly in the Corn Belt States and in some areas it is approaching equal status acreage with corn. Improved weed control technology is at least partially responsible for the increased acreage. The Southern US is a region of high temperatures and rainfall, both conducive to luxuriant crop and weed growth. The competitive effect of weeds with soybean growth necessitates optimum levels of control Generally, soybean varieties grown are of the bushy type, lapping rows relatively early, and giving shading of soil. Weed infestations prior to herbicide usage were a broad range of annuals, both grass arid broadleaf.
