Now's the time to develop a plan to how to prevent herbicide resistant weeds from popping up in your corn, soybeans, wheat or sugarbeets next spring and summer..
"Due to the long-term exposure to glyphosate in the corn and soybean cropping system, we are now in a situation where the probability of finding a glyphosate-resistant giant or common ragweed or waterhemp is high," says Jeff Gunsolus, a University of Minnesota extension weed specialist.
To address glyphosate-resistant weeds, Gunsolus says you must reduce total reliance on glyphosate and diversify weed-management practices, putting more emphasis on spring and early-summer weed control and a more focused use of glyphosate in the crop where its weed control is of greatest value to you.
Gunsolus recommends the following:
In all fields:
Select herbicide sequential and tank-mix partners for glyphosate that will effectively control the weeds that have become difficult for glyphosate to control.
Start with a pre-emergence residual herbicide to control early-emerging weeds and reduce the potential for crop yield loss due to weed competition from a delayed postemergence glyphosate application.
Glyphosate and postemergence tank-mix partners should be applied to 3- to 4-inch weeds for maximum effectiveness.
In fields currently infested with glyphosate-resistant weeds
Liberty Link corn and soybeans offer another postemergence herbicide strategy—the use of Ignite herbicide. Application to weeds 3 to 4 inches tall is critical, and best results are achieved when following a pre-emergence herbicide.
Limit glyphosate use in crops where effective herbicide alternatives to glyphosate exist. Target glyphosate use in crops where its weed control is of greatest value to you.
Use inter-row cultivation.
Rotate to early-season competitive crops, such as small grains.
"Take control of the situation now, so your weed seed bank doesn't remind you of your mistakes for many cropping seasons," Gunsolus says.
Source: U of M Extension Service