Glyphosate Resistant Weeds - Awareness to Growers and Ag Industry.

Glyphosate currently is applied to more acres of land than any other herbicide.  Glyphosate effectiveness, the development of glyphosate resistant crops, and the relatively low price of glyphosate has led to abundant glyphosate use.  With the increased intensity of glyphosate use, continued development of glyphosate resistant weeds (GRW) is a growing concern.    In 1996 the first GRW, annual ryegrass, was discovered in Australia, followed by goosegrass in Malaysia in 1997.  The first GRW of major concern in the USA was marestail or horseweed, first documented in Maryland in 2000, and now common throughout the Eastern, Southern, and Midwestern USA.  Currently five weed species have been identified as glyphosate resistant in Kansas with additional weed species currently suspected of having glyphosate resistance.  An Extension program has been developed to bring about awareness and education about GRW management in Kansas. An interactive survey of meeting participants during late 2008 and early 2009 provided public perceptions of several GRW issues.  Eighty five percent of respondents were concerned about GRW and 65% believe they directly or indirectly are affected by GRW.  Thirty five percent of respondents felt they had more than one species of GRW.  Only 68% of the respondents are implementing practices to prevent GRW.  A greater percentage of glyphosate resistant corn acres are being treated with conventional preemergence and postemergence herbicides compared to glyphosate resistant soybean acreage.    The authors perception is that the use of conventional herbicides in glyphosate resistant corn and soybeans is increasing because of GRW.  Clearly the GRW management/prevention message needs to be heard by growers and those involved in crop production to preserve the effectiveness and longevity of glyphosate herbicide.