Rapid Assay for Detecting Herbicide Drift

Glyphosate herbicide is a very versatile herbicide but may cause a problem if it drifts to susceptible crops. The susceptible crops may exhibit decreased growth, reduced yield, or even be killed if the drift dosage exceeds the target tolerance level. Thus, determining the type and degree of injury is important to a producer.

A quick and accurate method for detecting herbicide drift due to glyphosate has been tested by a group of researchers at the US Department of Agriculture’s Agricultural Research Service (USDA-ARS). The method relies on the accumulation of shikimate in plant leaf tissues when glyphosate is applied. The level of shikimate was measured using spectrophotometric assay of 4mm diameter leaf discs. Shikimate levels were compared at five different rates of glyphosate application.

The researchers found that the method can be used for detecting herbicide drift in sunflower, proso millet and wheat under greenhouse and field conditions. They recommend that producers should sample the most severely injured plants along the edge of the potential drift event if they choose to use the leaf disc assay.

Details of the study can be accessed by Weed Science journal subscribers at http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1614%2FWS-06-065.1.