Glyphosate-resistant Johnsongrass found in US:
The first US cases of glyphosate herbicide resistance in Johnsongrass (Sorghum halepense) have been found in the states of Arkansas and Mississippi. Scientists from Monsanto and the respective state universities have conducted greenhouse tests to confirm the findings. In both cases, resistance was confined to individual farms, with testing of other suspected resistant weed populations proving negative. The resistant weeds in Arkansas came from a field planted continually with glyphosate-tolerant Roundup Ready soybeans. Monsanto recommends the use of herbicides with alternative modes of action to "control problem weeds while reducing the likelihood of developing performance issues", says the company's US chemistry technical lead, Dr Jennifer Ralston. Glyphosate-resistant Johnsongrass was confirmed in Argentina in 2006 (Agrow No 504, p 12).