Reduced Herbicide Antagonism of Grass Weed Control through Spray Application Technique

Luke H Merritt,Ashli E Brown-Johnson,John Wesley Lowe,Daniel B Reynolds,Jason Connor Ferguson,Te-Ming Tseng

doi:10.3390/agronomy10081131

Luke H Merritt, Ashli E Brown-Johnson + Show 4 more

Open Access

https://doi.org/10.3390/agronomy10081131

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Abstract

Dicamba and 2,4-D tolerance traits were introduced to soybean and cotton, allowing for over the top applications of these herbicides. Avoiding antagonism of glyphosate and clethodim by dicamba or 2,4-D is necessary to achieve optimum weed control. Three field studies were conducted in fallow fields with broadleaf signalgrass (Urochloa platyphylla) and Italian ryegrass (Lolium perenne ssp. multiflorum) pressure. A tractor-mounted dual boom sprayer was modified to spray one of three application methods: (1) two herbicides tanked-mixed (TMX); (2) two herbicides in separate tanks mixed in the boom line (MIL); and (3) two herbicides in separate tanks applied through separate booms simultaneously (SPB). One study compared the three application methods with sethoxydim applied with bentazon, the second compared clethodim applied with dicamba or 2,4-D, and the third compared glyphosate applied with dicamba or 2,4-D. In most cases over all three trials, there was a 7–15% increase in efficacy when using the SPB application method. Antagonism of all the herbicide combinations above was observed when applied using the TMX and MIL methods. In some cases, antagonism was avoided when using the SPB method. The separate boom application method increased efficacy, which allowed herbicides to be used more effectively, resulting in improved economic and environmental sustainability of herbicide applications.

Highlights

Tank-mixing herbicides is a logistical way to apply multiple modes-of-action in a single herbicide application
Antagonism is when the result of two or more chemicals combined is less than the predicted effect of each herbicide applied separately, while synergism is when the response is greater than expected [1,3]
Field studies took place in three site-years at the Black Belt Experiment Station in Brooksville, in applications of row crops, it is important to know if a change in herbicide application method may Mississippi, USA and at the R.R

Summary

Introduction

Tank-mixing herbicides is a logistical way to apply multiple modes-of-action in a single herbicide application. Colby [1] produced a mathematical equation to determine if herbicide combinations produce antagonistic or synergistic responses. Colby’s equation for testing a two-herbicide combination is the following:. Where X is percent control of herbicide A, Y is percent control of herbicide B, and E is the expected amount of control. Antagonism is when the result of two or more chemicals combined is less than the predicted effect of each herbicide applied separately, while synergism is when the response is greater than expected [1,3]. The Colby method is widely used to determine antagonistic and synergistic combinations. Many factors affect herbicide antagonism including herbicide rate.

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