Howard F. Schwartz, Colorado State University
Washington State University officials are recommending Northwest farmers be cautious after reports that some pollinator seed mixes elsewhere were found to be contaminated with the weed Palmer amaranth.
“As far as we know, we don’t have Palmer amaranth, and that’s the fear, that these packets of seed will bring it here,” said Drew Lyon, weed science professor at WSU.
A Weed Science Society of America survey has labeled Palmer amaranth “the most troublesome weed in the U.S.” According to the society, some native seed mixes designed to foster habitat for honeybees and other pollinators in the Midwest were found to contain the weed. Seed mixes should be tested to make sure they are free of the weed.
“There’s a big push for pollinator health, and so a lot of people want to plant these things,” Lyon said. “It doesn’t sound like maybe quality control on the end of these companies is great. And that seed is really tiny. It’d be an easy mistake to make, but it could be a costly mistake to make.”
The weed is common in fields across the South and the Southeast, and has been traveling north for several decades. Its small seeds are easily spread by birds and farm equipment, and in birdseed, livestock feed and manure.
Lyon said it’s possible someone could unknowingly order contaminated seed mix online.
The warm-season, broadleaf weed could pose the most risk for irrigated production in the Columbia Basin. The crops growing in July and August would be most affected, Lyon said.
“It’s a very prolific seed producer,” he said. “It’s glyphosate resistant, and ... we use a lot of glyphosate in our ag systems. If we have a weed like Palmer amaranth that’s so prolific and can spread so quickly, and we can’t use Roundup to help us control it, it’s going to become a bit problematic.”
Lyon also advises growers to keep an eye out and be aware of what Palmer amaranth looks like.
“If you see it, pull it before it can set any seed,” he said.
Growers should also alert the university. Researchers would try to confirm the weed and the source of the seed mix and spread the word, Lyon said.
WSU researchers will wait and see if any Palmer amaranth is reported.
“I don’t know if it’s inevitable that it will get here some day, but it seems like things move pretty good,” Lyon said. “As far as I know, we don’t have it in the state right now. And that’s the best situation to be in.”