Professional Recommendations

The following links will provide you with weed management recommendations from university extension and academic experts. This information provides you with a third party perspective on weed control that is consistent with the general guidelines detailed in the Field Management section.

Dr. Kevin Bradley - Missouri Farmers Manage Herbicide-Resistant Weeds (.pdf, 888K)
Missouri farmers are coping with herbicide-resistant weeds, including one - waterhemp - that is resistant to three different herbicide chemistries, including glyphosate, ALS-inhibitors and PPO products. Agricultural scientists in the state also have their eye on Palmer amaranth and giant ragweed, watching for possible development of glyphosate and/or ALS resistance.

Dr. Stanley Culpepper - Spread of Palmer Amaranth in Georgia Requires Fine-Tuning Control Programs (.pdf, 777K)
Georgia farmers growing Roundup Ready® and Roundup Ready Flex cotton are tightening up their weed-control programs to meet the challenge of glyphosate-resistant Palmer amaranth. There are at least 19 Georgia counties confi rmed to be infested with this resistant species of pigweed, according to Dr. Stanley Culpepper, extension weed scientist at the University of Georgia.

Dr. Jeffrey Gunsolus - University of Minnesota Weed Scientist Encourages Farmers to Prevent the Spread of Glyphosate-Resistant Weeds (.pdf, 583K)
With cases of glyphosate-resistant common waterhemp and giant ragweed confirmed in Minnesota, University of Minnesota professor and extension agronomist Dr. Jeffrey Gunsolus says farmers need to be proactive in their weed management practices to help prevent the spread and development of glyphosate-resistant weeds.

Dr. Bill Johnson - Purdue University Weed Scientist Urges Farmers to Be Proactive in Controlling Morningglory and Waterhemp (.pdf, 606K)
According to Dr. Bill Johnson, extension weed scientist at Purdue University, morningglory and waterhemp are the two tough weeds that are causing him the most concern due to their potential for developing resistance to glyphosate. Currently, marestail and giant ragweed are confirmed as glyphosate-tolerant in Indiana, and Dr. Johnson stresses the importance of proactive weed-management practices to help prevent more weeds from developing resistance.

Dr. Kassim Al-Khatib - Effective Weed Control and Resistance Management Require a Mixture of Tools (.pdf, 870K)
Currently, Kansas has confirmed three glyphosate-resistant weeds: giant ragweed, common waterhemp and marestail. But according to Kansas State weed scientist Dr. Kassim Al-Khatib, all three resistant weeds resulted from similar farming practices. "Basically, the same diagnosis comes from someone who plants the same crop year after year, doesn?t do the right burndown treatments and, when it comes to a herbicide application in the field, he continues to use the same practices - particularly no diversification in his weed management practices," he explains.

Dr. James Martin - University of Kentucky Agronomist Encourages Farmers to Keep Marestail Under Control (.pdf, 834K)
According to University of Kentucky agronomist Dr. James Martin, farmers continue to struggle with keeping marestail under control. "Marestail has a high degree of tolerance to glyphosate, and farmers need to take the steps to manage it," says Dr. Martin.

Dr. Mike Moechnig - Structure Weed-Control Programs to Fight Herbicide-Resistant Weeds (.pdf, 7806K)
There are currently four herbicide-resistant weed species confirmed in South Dakota: ALS-resistant kochia, ALS-resistant wild sunflower, glyphosate-tolerant common ragweed and ACCase-resistant wild oats. This list may well increase soon if state farmers don't take some countermeasures in their weedcontrol programs, according to a South Dakota State University weed scientist.

Dr. Mike Owen - Stewardship of Glyphosate Must Become a Primary Focus (.pdf, 684K)
According to Iowa State University weed scientist Mike Owen, weed shifts and the evolution of glyphosate-resistant weeds are on the rise. "Stewardship of glyphosate must become a primary focus of our Midwest crop-production systems," says Owen. "It is important that stewardship decisions enhance and preserve crop traits, but are also economically rewarding and environmentally sustainable."

Dr. Ken Smith - Arkansas Farmers Focusing on Resistant Palmer Amaranth (.pdf, 790K)
The pigweed species Palmer amaranth is quickly becoming the number one weed challenge for Arkansas cotton growers. The problem: Much of the Palmer amaranth population is resistant to two popular herbicide chemistries, ALS-inhibitors and glyphosate.

Dr. Larry Steckel - Tennessee Farmers Getting Handle On Herbicide-Resistant Weeds (.pdf, 775K)
Roundup Ready® and Roundup Ready Flex cotton farmers in west Tennessee have dealt with glyphosate-resistant marestail for several years now, and control strategies have evolved, providing an acceptable level of control.

Dr. Robert Wilson - University of Nebraska Extension Weed Specialist Encourages Farmers to Invest More in Weed-Control Program (.pdf, 606K)
In addition to glyphosate-resistant marestail, many farmers in Nebraska are finding palmer amaranth, tall waterhemp and lambsquarters difficult to control with glyphosate alone. "Some farmers try to reduce their weed control cost, allowing some weeds to go to seed which adds weed seed back into the seed bank," says Dr. Robert Wilson, extension weed specialist at the University of Nebraska.

Dr. Bryan Young - Residual Herbicides Keep Glyphosate-Resistant Weeds from Spreading (.pdf, 815K)
According to Dr. Bryan Young, weed scientist at Southern Illinois University, glyphosate-resistant marestail is becoming more of a management challenge for farmers in his state. "Over the last couple of years, we've seen glyphosate-resistant marestail spread to a bigger geography," he says. Glyphosate-resistant common waterhemp has also been confirmed in Illinois. "We anticipate a growing number of fields containing glyphosate-resistant waterhemp in coming years as well."