Farmers should initiate weed control to oppose glyphosate-resistant weeds
WEST LAFAYETTE, Ind. – As spring progresses, farmers and other agriculturalists will be seeing more weeds growing throughout their fields.
“Farmers should start thinking about a plan for their herbicide choices to help control the weed problems that they might have,” said Bill Johnson, Purdue Extension weed specialist.
Johnson explains that Indiana has four common glyphosate-resistant weed problems: Marestail is already in many no-till fields that will be planted in soybeans because it can behave as a winter annual or a summer annual. Giant ragweed, common ragweed and common waterhemp are summer annuals and will start emerging as soon as extended periods of warm daytime air temperatures occur.
Although marestail is found throughout Indiana, in southern parts of the weed will usually emerge as early as mid March and continue to emerge through the spring and early summer. Glyphosate-resistant marestail is becoming a bigger problem in northern parts of the state, and growers should plan their weed management programs to combat it.
Johnson said applying burn down herbicides with residual activity to fields will help control marestail and other weeds.
“I suggest farmers apply a pint of 2, 4-D with their burn down program because it is a very inexpensive herbicide,” he said. “The downfall to using 2, 4-D is that farmers must wait seven days to plant after it has been applied.”
Another option Johnson suggests is a herbicide containing saflufenacil, which can be applied in place of 2, 4-D for marestail control. The herbicide is a little more expensive, but there is no delay in planting.
Johnson advises farmers to control other early emerging weeds before they plant by using a residual herbicide with the burn down program and timely post-emergence spraying after planting, if needed.
Selecting which seed to plant also is a crucial part in weed control and herbicide application.
“Although farmers should spray their burn down program before they plant, it is crucial they know what seed they will be planting,” Johnson said. “The herbicide-resistance trait a seed carries will determine what herbicide can be applied to that field.”
Johnson suggests that farmers have a weed control strategy in mind as spring approaches.
“Farmers should know what their worst weed problem is and have more than one herbicide mode of action for it,” he said.
For more information visit the Purdue and Ohio State Weed Guide Web site at https://www.btny.purdue.edu/Pubs/WS/WS-16/WS-16.pdf, or contact Johnson at 765-494-4656 or wgj@purdue.edu
Writer: Sayde Rayburn, 765-494-8402, srayburn@purdue.edu
Source: Bill Johnson, 765-494-4656, wgj@purdue.edu
Ag Communications: (765) 494-8415;
Steve Leer, sleer@purdue.edu
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