Pigweed plagues Louisiana farms

Louisiana Department of Agriculture & Forestry

BATON ROUGE – A weed originally discovered in Georgia continues to spread across the south and has been known to be present in Louisiana for some time. “Initially, glyphosate, the active ingredient in the popular herbicide Roundup, would kill the weed. Unfortunately, the weed has become resistant,” said Louisiana Department of Agriculture and Forestry Commissioner Mike Strain, D.V.M.

Palmer Amaranth (a type of pigweed) started plaguing Louisiana farms in 2010. Since this pigweed has become resistant to certain herbicides commonly used to control the weed, it is becoming a real problem for corn, cotton and soybean farmers. It can also be troublesome for other crops.

“One of the best methods of control is to prevent the introduction of the seeds on a farm so the plant does not get a foothold. This can be done by cleaning equipment before moving it between fields and ensuring custom harvesters are thoroughly cleaning their equipment before entering a new farm,” said Strain. “In addition, the weed control research done by the LSU and Southern ag centers is essential to protecting our state’s crops and the agricultural industry.”

Pollen transfer from herbicide-resistant pigweeds to other pigweeds can occur over very long distances. Pigweed found in Mississippi and Tennessee has recently proven to be resistant to a different group of herbicides, further limiting control options for this weed.

In addition to cleaning equipment, it is best to alternate use of herbicides that still show effective control. But preventing the introduction and spread of resistant pigweed to the farm through diligent cleaning of equipment is still the best way to avoid introduction of the invasive plant.