Supplementary weed control using soil-applied herbicides in glyphosate-resistant maize in Texas

Field studies were conducted during the 2000 and 2001 growing seasons to evaluate the effects of glyphosate with and without soil-applied herbicides on weed control and yield in Zea mays. In 2000, under above normal rainfall conditions, glyphosate used alone provided poor control of Amaranthus albus when applied early post-emergence but gave improved control when applied later in the growing season. Brachiaria platyphylla control was poor with glyphosate alone applied early post-emergence and improved when applied later in the season. In 2001, a below normal rainfall year, A. albus and B. platyphylla control were very good with all glyphosate only applications. When a soil-applied herbicide was applied pre-emergence prior to glyphosate applied post-emergence, A. albus and B. platyphylla control was greater than 85% in both years. The use of soil-applied herbicides improved the reliability of weed control in glyphosate-resistant maize.