Herbicide Resistant Weeds

Speaker 1: For years farmers have controlled a common weed, such as Johnsongrass and pick weeds in their fields with the herbicide Glyphosate. It was inexpensive and it worked well, but it’s not working well anymore. In areas of Arkansas, Georgia, Mississippi, and Tennessee, weeds have developed a resistance to Glyphosate. LSU AgCenter weed scientist, Dr. Daniel Stephenson, suspects that the problem has reached Louisiana.
Dr. Stephenson: Confirmed it yet, scientifically? No, but we are an eyelash away.
Speaker 1: The issue is a byproduct of the over reliance on Glyphosate. Herbicide resistant weeds could cause serious problems for soybean growers. The pick weed, Palmer amaranth can grow two inches a day and out competes soybean plants for sunlight and water.
Dr. Stephenson: If you’ve got a soybean plant and it’s only growing about an inch every couple of days, and you’ve got that Palmer that’s putting on two inches a day, the Palmer can shade the soybeans, compete with it just being close together.
Speaker 1: Stephenson says growers should make adjustments to keep weeds in their fields from developing resistance to Glyphosate and to ensure Louisiana doesn’t develop the same problems other states are experiencing. Using herbicides in the fields before plants emerge, crop rotations, and narrowing the row space in a soybean field can help in the fight against weeds. Dr. Brooks Blanch says, “Narrower rows build a better canopy and can increase yields.”
Dr. Blanch: You’re getting maximum light interception and maximum photosynthesis per area of ground, and also because of the shading and because of the increased competitive ability of the crop, you’re reducing weed competition as well.
Speaker 1: Stephenson said it’s only a matter of time before Glyphosate resistant weeds officially are confirmed in Louisiana. It’s important that farmers take steps now to get the problem under control. With the LSU AgCenter, this is Toby Blanchard, reporting.