Midwest farmers struggling with waterhemp control issues have a new resource for information--thanks to the efforts of university weed scientists Kevin Bradley at the University of Missouri, Bob Hartzler at Iowa State University and Dawn Nordby at the University of Illinois. The result of this collaboration is "Biology and Management of Waterhemp", a brochure created to help farmers minimize yield losses from this tough to control weed.
The publication also has information on how to manage the development of herbicide resistance. "Waterhemp is probably the No. 1 concern in the Midwest because everyone has it," says Nordby. "With this publication, we wanted to give a history of how waterhemp went from obscurity just 20 years ago to the leading offender in resistant weeds today."
Waterhemp density and its potential impacts on crop yield present the biggest concern for farmers.
Yield and cost of control are concerns
"The other issue is that waterhemp control does significantly increase management costs in terms of having to use additional traditional applications of herbicide," says Hartzler. "The adaptability of waterhemp to our management practices is the primary reason it has become the No. 1 weed problem for many farmers in the Western Corn Belt."
One of the primary goals of the publication is to address the current waterhemp situation and to encourage farmers to take action now.
"We wanted to paint a clear picture of what will happen when weeds develop resistance to glyphosate. We will basically lose all our mode of actions for controlling waterhemp," says Nordby. "But there are options out there to prevent this from happening and if farmers want to do something about this problem, they need to do it now."
Farmers need to take action now
Bradley supports a preventative approach to managing herbicide-resistant waterhemp. "The No. 1 treatment method is to avoid applying the same herbicide year after year; that is where prevention meets management. The key is mode of action rotation when you choose which herbicide products to use. By using an effective preemergence herbicide like Sonic, Authority First, Valor, Dual II Magnum or any of the other options listed in our new publication, you can control populations that have exhibited resistance to glyphosate," he says.
"Biology and Management of Waterhemp" is one of several publications available in "The Glyphosate, Weeds and Crops Series". The series will be comprised of 10 publications, each focusing on a particular aspect of glyphosate stewardship, including individual weeds which have become more problematic to control in Roundup Ready cropping systems.
The goal of the series is to create an easy-to-use tool for farmers, retailers and crop advisors that will help them manage weeds and preserve the benefits of the Roundup Ready cropping system technology. Other publications in print in the series include "Biology and Management of Horseweed, Biology and Management of Wild Buckwheat", "Facts about Glyphosate-Resistant Weeds", "Understanding Glyphosate to Increase Performance", "Biology and Management of Common Lambsquarters"; and "Biology and Management of Giant Ragweed".
You can attain a copy of these publications through the Glyphosate Stewardship Working Group's Web site at www.glyphosateweedscrops.org or by contacting your state Extension weed scientist.