Illinois Ag News Headlines Free Testing for Glyphosate Resistance in Waterhemp Illinois Ag Connection - 07/29/2010 Waterhemp populations resistant to glyphosate are becoming increasingly common across Illinois, said University of Illinois Extension weed specialist Aaron Hager. "We suspect that resistant biotypes can be found in many areas across Illinois, but would like to improve our understanding of just how widespread these biotypes are right now," Hager said. "Post-emergence applications of glyphosate to soybean fields are occurring at a rapid pace, given the recent spell of good weather." Because of this, Hager expects that glyphosate-resistant waterhemp plants will become noticeable approximately 7 to 10 days after these applications. Producers with waterhemp populations that may be resistant to glyphosate are invited to send waterhemp samples to the U of I for free herbicide-resistance testing. Samples will be tested for resistance not only to glyphosate, but also to the PPO and ALS inhibitors. Hager said they can't promise a specific turnaround time because testing is a free service. In addition, due to the way in which the resistance tests are conducted, a test result of "sensitive" does not rule out the possibility that the plant actually is resistant, only that it's resistant by a mechanism different than what they are testing. For more information, contact Pat Tranel, U of I weed scientist, at (217) 333-1531 or tranel@illinois.edu. Copyright © 2010 - USAgNet.com. All Rights Reserved.