Evaluating Marestail Control with Wheat Herbicides

Marestail (also known as horseweed) is an annual broadleaf weed that can emerge in wheat. While it may sometimes interfere with wheat harvest, the greatest concern is its impact on double-crop soybeans following wheat harvest. Marestail is especially difficult to control since most populations are tolerant to glyphosate. Some herbicides used in the wheat crop are believed to control marestail yet this has not been well documented by research. Attempts have been made during the last 3 years to evaluate various herbicides for marestail control in wheat. A study in 2010 indicated very little if any improvement in marestail control with preharvest of treatments. The emphasis changed in 2011 and 2012 to evaluate postemergence treatments applied in the fall or spring. The marestail infestation was too erratic in the 2011 study to obtain meaningful data. However, results in 2012 indicated some treatments improved marestail control. Continue to evaluate the effect herbicides on managing marestail in wheat.