On lookout for invasive weed
Jefferson County Weed Commissioner Dan Miller wants residents to be alert for an invasive weed sweeping across the state.
The weed is palmer amaranth, and it poses a nuisance because it can grow so quickly and therefore crowd out row crops. A press release from Bob Hartzler of Iowa State University Extension and Outreach indicated the weed is known for its prolific seed production and resistance to multiple herbicides.
Miller said the weed has not reached Jefferson County as far as he knows. However, it is spreading so rapidly that he wants farmers and landowners to be on the lookout for it nevertheless.
Iowa State University Extension field agronomist Rebecca Vittetoe said the weed was first identified in Iowa in 2013. Before 2016, it had only spread to five counties, but she said it has now been identified in 48 of the state’s 99 counties.
Miller said that a few years ago, conservation seeds were running low in Iowa, so a mixture of seeds was brought in from out of state. Unfortunately, this seed mixture contained Palmer amaranth seeds by mistake. Iowa farmers who planted the seed mixture on their Conservation Reserve Program land have been unwittingly spreading the weed.
“This weed needs to be taken care of because it’s very aggressive,” Miller said. “It can shade out row crops, and that can be a real problem.”
The best way to get rid of the weed is to pull it when it’s young or keep it cut so it can’t go to seed, Miller said.
Vittetoe said palmer amaranth can be difficult to distinguish from other pigweed plants such as waterhemp, redroot pigweed, powell amaranth and spiny amaranth. She said hairs on the stem are distinguishing features of redroot pigweed, smooth pigweed and Powell amaranth, while the others, including palmer amaranth, have hairless stems.
The main way of differentiating between palmer amaranth and waterhemp is that palmer amaranth has a longer petiole compared to its leaf. The petiole is the part of the weed that connects the stem to the leaf.
“If the petiole is longer than the leaf blade then you are most likely looking at palmer amaranth,” Vittetoe said.
Vittetoe said she doesn’t want farmers to fear establishing CRP ground, but she does advise them to purchase locally produced seeds.
Miller said any landowners who spot palmer amaranth on their property should call him at 472-2561.