To learn more about herbicide resistance in weeds in Minnesota, the University of Minnesota Extension weed science team is asking growers to send them weed seed samples from their fields.

Debalin Sarangi, U-MN’s new Extension weed scientist, says they are asking growers to submit seed samples for weeds that survived preemergence or postemergence herbicide treatments.

“We’re targeting common weed species and would like to know if there are any hot spots out there,” Sarangi says. Seed samples can come from a variety of weeds — waterhemp, redroot pigweed, giant ragweed, common ragweed, common lambsquarters, marestail, kochia, foxtails and barnyardgrass.

“Right now, we heavily rely on pre emergence herbicide,” Sarangi adds. “If we lose that, it would be a major loss in regard to waterhemp management.”

Testing for herbicide resistance is free to growers. There is no deadline for submitting samples this year.

To find and submit samples:

Look for weed escapes. Collect samples from a field with a history of herbicide resistant weeds or from a random field where you see weed escapes. Check seed heads for mature seeds. Depending on the weed species, seeds may occur on the seed head, on branches or at leaf axils. Male plants don’t produce seeds.

Collect seeds. Clip weed seed heads from five or more plants per field. Place them in paper bags. Do not use plastic bags as they promote mold growth. Seal the paper bags carefully. Label each with your name and email address; GPS coordinate of the collection site or township and ZIP code; crop and weed names; herbicides applied this season; field history.

Send them in. Ship the seeds to Debalin Sarangi, 411 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108. Or, take samples to your local crops Extension educator.

SHIP IN SACKS: Growers are asked to send seed head samples in paper sacks to prevent them from getting moldy. This sack is full of waterhemp seed heads.

Sarangi says the weed science team will grow the seeds in the greenhouse on the St. Paul campus and screen them for possible herbicide resistance. Results are usually available within six months after submission, he adds, although it may take longer depending on the weed species and the number of samples received.

Extension weed scientists will document where herbicide-resistant weeds are in the state and create distribution maps showing common weeds.

Questions? Contact Sarangi at [email protected] or 612-625-8130.