Don't Get Behind With Roundup-Resistant Pigweed, Says Arkansas Farmer

From February's National Conservation Cotton and Rice Conference in Baton Rouge, Louisiana:

Wayne Wiggins, of Arkansas, said herbicide-resistant pigweed appeared on his farm rapidly. “I was just stunned at how fast it came on.” He said it’s important to talk with neighbors about their weed problems and be prepared for resistance issues. 

“You’ve got a narrow window. When you get behind, you are over and done.” Wiggins said he uses atrazine on corn for its residual effects. “I’ll use a residual on all my bean fields this year.” 

He said rice is a good rotation crop to address pigweed, but the weed must be controlled on levees.

Source: Bruce Schultz, LSU Ag Center

Hooded Sprayer From Wilmar Aimed Directly At Roundup-Resistant Weed Control

Hooded sprayers were left to rust and rot in the weeds after Roundup Ready became the dominant weed control measure in cotton and other crops in the South.

Now, though, with the shift toward more Roundup-resistant weeds, hooded sprayers have been reentering fields, and more units are being sold.

Roundup-Resistant Ryegrass: Mississippi Schedules Symposium For March 10

Mississippi farmers are a few years into the fight against glyphosate-resistant weeds, a problem that is the focus of a March 10 field day in Stoneville.

Producers will take a close look at ways to manage herbicide resistance in the Glyphosate-Resistant Ryegrass Field Day at Mississippi State University’s Delta Research and Extension Center in Stoneville. Registration begins at 7:30 a.m. at the Capps Center, and the field day concludes with lunch. The program will move indoors if there is bad weather.

Conventional Cotton Herbicide Control: One Approach

Editor's Note: Rusty Harris, Extension Agent in Worth County, Georgia, developed the following systems approach for his farmers who want to grow cotton that lacks herbicide resistance traits:

This program should provide adequate control of palmer amaranth, ipomea morningglory species, yellow nutsedge, bristly starbur, and tropic croton.

Roundup-Resistant Pigweed Management Plan For 2011 From Georgia

R.J. Byrne, Extension Agent in Thomas County, Georgia, has produced a short video (see below) about Georgia's approach for controlling Roundup-resistant Palmer pigweed in cotton. In the video, Byrne interviews Stanley Culpepper, Georgia Extension Weed Scientist.

Here's a supplemental handout that goes into more detail about herbicides, rates and other factors touched on during the video.

Arkansas Resistant Palmer Pigweed Field Day Video From Arkansas

Arkansas Soybean Verification Coordinator, Chris Grimes, discusses this year's experience with trying to control herbicide resistant pigweed in soybean after rain kept researchers from making a much-needed Valor herbicide application.

Louisiana Confirms First Case Of Roundup-Resistant Palmer Pigweed, Water Hemp Issue Also Suspected

Roundup-resistant Palmer pigweed (aka Palmer amaranth) has been confirmed for the first time in Louisiana, according to a memo from Daniel Stephenson, LSU AgCenter Weed Scientist.

The memo was included Sunday morning, September 5, in AMS AG REPORT, the weekly newsletter published by consultant Roger Carter with Agricultural Management Services, Inc., a firm that covers several parishes in east-central Louisiana.

Carter said that Tim White, a consultant in the firm, "has worked on this farm with Dr. Stephenson for several years trying to manage this weed. This particular farm is near Lake St. John."

Stephenson noted in the memo that Roundup-resistant Palmer pigweed already had been confirmed in Alabama, Arkansas, Georgia, Mississippi, Tennessee and several other other states.

Stephenson reported that he had now "confirmed that Palmer amaranth collected from a cotton field in Concordia Parish is resistant to glyphosate."

According to his analysis, 50% of the Concordia Parish population "is approximately 54 times less sensitive to glyphosate compared to the susceptible standard. In other words, if the labeled use rate of glyphosate is 32 fluid ounces/Acre, a producer will have to apply 118 oz/Acre of glyphosate to control 50% of the Palmer population or 723 oz/A to control 90% of the population.”

In a followup memo Sunday afternoon, Stephenson noted that other cases of hard-to-control pigweed were being investigated.

"Unfortunately, LSU AgCenter weed scientists are following up on many other locations throughout Louisiana where Palmer amaranth or waterhemp, another Amaranthus species, have not been effectively controlled by glyphosate," he noted. "Any producer or consultant in Louisiana should be aware of the potentially devastating effect herbicide-resistant weeds can have on their crop. If you suspect that a weed population is resistant to a herbicide (not just glyphosate, ANY herbicide), please contact your local LSU AgCenter county agent.

"AgCenter personnel need to know of these issues so we can help you avoid or mitigate weeds resistance from spreading throughout Louisiana."

- Owen Taylor