Think You've Seen Weed Pressure? Think Again.

Prairie Gleanings

The longer you put off getting serious about weed resistance managment, the more it could cost you.

Published on: August 22, 2011
There are some things in life you have to see for yourself to really appreciate them. Unfortunately, Arkansas’ invasion of Palmer Amaranth, commonly called pigweed, is just such a situation.

As part of Dow AgroScience’s Crop Technology Media Summit, we flew to Batesville, Ark. to witness the pigweed problem. At a farm near Newport, Ark., farmer Malcolm Haigwood explained the situation.

In 2005, the first pigweed problem was identified in eastern Arkansas, near the Tennessee border. In 2006 and 2007, the weed didn’t make much of an appearance. Then, in 2008, it came back with a vengeance. Today, farmers are fighting full-blown infestation. In many instances, conventional post-glyphosate programs have proven ineffective.

The only thing separating these two fields is a dirt road. It took one pre-emergence and three post-emergence applications to keep the one in the foreground clean. The field in the background got two poorly timed post-emergence glyphosate applications. By the way, the crop in the background is also soybeans.

During the discussion, Haigwood pointed out a clean soybean field, right across the road from one over-run by pigweed. The difference? Herbicide application management.

In both fields, glyphosate was the primary post emergence herbicide of choice. The over-run field got two post apps of glyphosate. The clean field got three post apps of glyphosate, along with three other chemistries. The clean field also had a pre-emergence herbicide applied.

University of Arkansas weed specialist Bob Scott says it’s not a matter of if Illinois will have a pigweed program, it’s a matter of when. A lot of Arkansas farmers are relying on hoe crews to get pigweed infestations under control.

To date, glyphosate resistant waterhemp has been getting the most press in Illinois. A number of new herbicide tolerant crops are on the horizon, including tolerance to 2,4-D and dicamba. Still, these options won’t be available for at least a couple more years.

Witnessing the situation in Arkansas, I’d say now is the time to get serious about weed resistance in our state. The days of $15/acre glyphosate are probably over. It is in Arkansas. Those folks are now paying around $65/acre to control weeds.

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