The Clarion Call

Unfortunately, regrettably, lamentably, Dr. Powel was right. Resistant marestail is almost a fact of life in the Mid-South and Southeast, and resistant Palmer amaranth is spreading.

Not only is resistance spreading geographically, it is spreading to other species.

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It’s almost universally accepted that the first line of defense in preserving glyphosate and ALS technology begins with tank mixing them with residual herbicides. Applications of residuals can begin as early as immediately post-harvest, all the way through layby.

Recommendations from the Louisiana State University Ag Centers say all of that: The best way to delay or prevent weed resistance is through the use of tillage, crop rotation and herbicides with different modes of action.

Any weed scientist will tell you that total reliance on glyphosate is simply going to get you in trouble, and the manufacturer of Roundup agrees.

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“Dr. Stanley Culpepper told me that in 2005, there were about 50,000 acres with resistant Palmer amaranth in Georgia. In 2007, he said it was more like 250,000 acres,” says Dr. Jennifer Ralston, Monsanto Technology Development Manager. “At Monsanto, we want to communicate the fact that there is weed resistance developing, and provide management solutions so that growers can be successful with the Roundup Ready system.”

“To say that (resistance) has changed our thinking and our way of life is an understatement,” says Dr. Alan York, William Neal Reynolds Professor of Crop Science and Extension Specialist at North Carolina State University. “It’s time we started to take resistance management more seriously.”

Adds Ralston, “The reality is, that if we don’t change the way we do things, resistance is going to continue to grow. We have to change our practices.”

“Practically speaking, the best thing we can do to head off resistance is greater diversity in the chemistry we are using,” adds York. “We are recommending in North Carolina a minimum of two modes of action in corn and soybeans, and a minimum of three in cotton.”

Caption:
Marestail control vs. resistance.

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