Italian ryegrass showing classic signs of resistance

Published on: 12:56PM Oct 30, 2009
Chuck Foresman
Glyphosate-resistant Italian ryegrass has been a problem in Mississippi for a couple of years. But in 2009, growers in other areas had more trouble with this tough weed.  One of my colleagues in western North Carolina shared these photos from a grower.
30 oz. of glyphosate                                   30 oz. of glyphosate and a 3x glyphosate application
Evidence you may be dealing with resistance is live weeds next to dead weeds of the same species. Other signs of weed resistance include effective control of other weed species on the herbicide label, but lack of effective control of a weed that was controlled in past years. Of course, you have to make sure that rate and timing of the herbicide application is right, and that weather and growing conditions were reasonably normal at application before you jump to conclusions.

Are you able to control Italian ryegrass effectively? Are their other weeds that glyphosate is not controlling well?