There is increasing concern in more northern states about the tremendous weed problem in the South — most notably the dreaded herbicide resistant Palmer amaranth.
The notorious weed has been making appearances in Ohio fields.
“It has been found in more than one location in Fayette County,” said Mike Earley, an agronomist with Seed Consultants, Inc. “If we catch it at two or three inches we are able to control with Cobra, or Flexstar or Prefix, which is a Dual/Flexstar premix. About the only other thing to do for it is Liberty.”
Palmer amaranth is in the pigweed family, so it looks similar.
“The leaf petiole is going to be longer than the leaf if you break it off from the stem. That is the first identifying factor and it has a hairless main stem,” Earley said. “It is tough to identify if you don’t know what to look for.”
The seed is getting into Ohio in a variety of ways.
“It is coming out of different places,” Earley said. “It is coming from cottonseed for dairies that pass through the manure. Seed from CREP acres is another source. If you are going to sew some new CREP acres, be sure to have the seed tested to make sure you’re not planting resistant Palmer amaranth. The seed coming out of Texas is all Roundup resistant. It is a tough weed and something we don’t want to mess with.”
Weed control specialist Mark Loux and his team at Ohio State University Extension have been closely keeping tabs on the Palmer amaranth situation in Fayette County and around the state.
“We started looking for it a couple of years ago more aggressively. We haven’t really found it in our surveys that we do, but people contact us and we go out and see what is going on. We do have a pretty good idea of what is out there. We probably have about eight sites,” Loux said. “We have one multi-site area west of Washington Courthouse that we are tracking and it is radiating out. The rest are individual fields here and there. We don’t really have any other areas where there are a lot of fields infested.”
The key is to quickly identify the weed and take proper control measures.
“We are in a preventative mode here in the state. As soon as we identify an infestation, we try to link up a local dealer or supplier with that grower. We want to make sure they know the most important thing is preventing those plants from going to seed. If we get to the next step, where we know we have a field with a history of the plants, then we make sure they have the information they need to get a more aggressive program in place,” Loux said. “We do not want this weed here and we are doing everything we can to keep it out. The guys in the South have been battling this and it has doubled their herbicide costs. Once it reaches about three inches tall, the weed specialist in Tennessee recommends just tearing up the field and starting over. It is a matter of getting the right herbicide in place and implementing it.”
Loux urges farmers to be vigilant about keeping Palmer amaranth out of their fields.
“It is difficult for me to get across how problematic this weed is. I can’t overestimate it. It combines all of the different characteristics of the various aggressive weeds we have into one and it is really a pain in the neck,” he said. “I am cautiously optimistic. The state knows we need to keep this out. We have information in place on this and we certainly do have herbicide programs that can control it. If we do find a field that is infested and get somebody on it with an aggressive herbicide program I think we will be in good shape. Except for the one area around Washington Courthouse, we kind of held steady from last year to this year. I hope we stay there.”
For more on identification and management of Palmer amaranth, visit http://u.osu.edu/osuweeds/super-weeds/palmer-amaranth/.