scientist. “Known infestation is less than 200 acres, all associated with conservation planting.”
Minnesota and Ohio name Palmer amaranth a prohibited seed. “We’re in eradicate mode, removing the weed, getting rid of the seed and flaming to get rid of plants,” Gunsolus adds. The issue remains: Palmer amaranth is creeping into CRP seed mixes. Even if the state eradicates weeds currently present, the threat still looms. “Iowa had considerably more CRP acres than any other state last year, up to 200,000 new acres, and that increase in demand for native seeds overwhelmed local seed producers,” Hartzler says. “Because of our increased demand our local seed producers had to source out of state and that’s where we think Palmer came in.” In a perfect world, native seed would be grown in the state it’s needed. This would help ensure no outside grasses or forbs make their way in, but when demand exceeds expectation or unexpected weather events hurt seed production it might not be possible. “Anything coming from Kansas, Arkansas—really any southern state that has Palmer is likely to bring it in,” says Kevin Bradley, University of Missouri weed scientist. While Missouri hasn’t identified Palmer in CRP planting specifically, weed scientists are on high alert.
Palmer amaranth is one of nearly 200 different pigweed species, and because they’re all in the same family they tend to look very similar, particularly waterhemp. Use specific plant characteristics to positively identify the difference, and when in doubt call an expert. “Look for long petioles on the leaves,” says Kevin Bradley, University of Missouri Extension weed scientist. “Then combine petiole length with leaf shape to tell if it’s Palmer or waterhemp.”
Learn How to Identify Palmer Amaranth
It’s harder to differentiate the two during early vegetative stages, but Palmer’s petioles will be longer than its broad, diamond-shaped leaves, and waterhemp has short petioles with more elongated leaves. When the seed head is present, female Palmer amaranth will have large, sharp bracts at the base of each flower and longer seed heads. Once Palmer amaranth gets seed heads, do all you can to destroy the seeds it creates without spreading them.