Better Test for Glyphosate Resistant Cotton Weeds

John DavisCotton, USDA

Cotton pickerA USDA Agricultural Research Service scientist is working with Monsanto to develop a kit that cotton growers could use to determine whether weeds in their fields are glyphosate resistant. Don Parker, Manager of Integrated Pest Management for the National Cotton Council, explains that early detection is key in managing glyphosate-resistant weeds.

“If a resistant weed is detected early, alternative measures can be employed to try to prevent the spread of that resistance,” he says.

Parker says scientists can determine the resistance to glyphosate in a weed by measuring the amount of the compound shikimate in the tissue. Glyphosate interferes with the production of aromatic amino acids through the shikimate pathways in weeds. “Glyphosate disrupts this pathway, causing shikimate to accumulate so plants susceptible to glyphosate will have high levels of shikimate, while resistant plants will not.”

He says the current detection methods for detecting shikimate takes sophisticated lab work that can take weeks. But this new method can return results in about 24 hours.