ARS | Publication request: Dissipation and Movement of Soil-applied Herbicide Combinations in Corn, Dry Bean and Sunflower

Submitted to: Western Society of Weed Science Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 7, 2011
Publication Date: March 8, 2011
Citation: Shaner, D.L. 2011. Dissipation and Movement of Soil-applied Herbicide Combinations in Corn, Dry Bean and Sunflower. Western Society of Weed Science Meeting Proceedings. March 8, 2011 Spokane Washington

Technical Abstract: Pre-emergent herbicides are used to control weeds in most of our crops. Combinations of herbicides are applied to broaden the spectrum of weeds controlled. Although many studies have been done on the behavior of individual herbicides in the soil, there are few studies that examine the fate of multiple herbicides applied at the same time. In this study the fate of herbicide combinations (atrazine and metolachlor in corn, flumioxazin and metolachlor in dry beans and pendimethalin and sulfentrazone in sunflowers) in different crops was measured over two years. The herbicides varied in soil binding and in rates of dissipation. In sunflowers, pendimethalin remained in the top 7.5 cm of the soil column, whereas sulfentrazone moved rapidly down the profile with heavy irrigation or rainfall. Flumioxazin also remained in the top 7.5 cm along with metolachlor. However, flumioxazin rapidly dissipated compared to metolachlor. In corn, atrazine moved more readily in the soil with a heavy rainfall compared to metolachlor. Atrazine also rapidly dissipated after the soil temperature increased due to enhanced degradation. Metolachlor dissipated at similar rates in corn and dry beans. The fate of each of the herbicides did not appear to be affected by the presence of other herbicides in the same soil.