November Weed of the Month: Palmer Amaranth

November’s Weed of the Month is Palmer amaranth (Amaranthus palmeri). This fast growing weed has developed resistance to multiple herbicide modes of action so it is difficult to control. Palmer amaranth produces a lot of seed, up to 250,000 per plant, and is highly competitive. It spreads quickly and will cause extensive corn and soybean crop losses.

Palmer amaranth is native to the arid southwestern United States and northwestern Mexico. It was accidentally introduced to the southeastern United States and became the most troublesome weed in cotton production, by far. It developed resistance to many herbicides with multiple modes of action and spread to row crop fields in much of the eastern half of the country. This dreaded weed was discovered in Minnesota in 2016.

Palmer Amaranth weeds

Palmer amaranth plant with seed spikes. (photo provided by the Minnesota Department of Agriculture.)

Palmer amaranth can be distinguished from closely related waterhemp and other pigweeds by a long petiole length and very tall flower and seed spikes. Unlike other pigweeds, Palmer petioles are often longer than the leaf blades. A petiole attaches a leaf to a stem. The flowering spike is much longer than that of other pigweeds. Leaves of some Palmer plants have a whitish V-shaped mark on them. Palmer amaranth is a summer annual that commonly reaches heights of 6-8 feet but can reach 10 feet.

If you find this plant, please report immediately by calling the Arrest the Pest at 888-545-6684 or emailing

Palmer amaranth detected in Minnesota

 ST. PAUL, Minn. – Crop scientists at the University of Minnesota and officials at the Minnesota Department of Agriculture (MDA) urge farmers to check fields for Palmer amaranth, an aggressive weed that can put corn and soybean crops at risk. A plant detected in a native seed planting plot on a Yellow Medicine County farm was confirmed today to be Palmer amaranth. This is the first confirmation of the weed in the state.

The MDA asks possible infestations to be reported by contacting the MDA’s Arrest the Pest line by phone at 1-888-545-6684 or by email at Landowners are encouraged to email photos of suspected infestations for identification.

“We encourage landowners to scout fields now before harvest for Palmer amaranth and report any possible infestations to the Minnesota Department of Agriculture,” said Geir Friisoe, MDA’s Director of Plant Protection. “The quicker we’re able to identify and start managing this weed, the better our chances will be to minimize the impact to our ag industry.”

Palmer amaranth

Palmer Amaranth has been found in Minnesota and the Department of Agriculture wants farmers to keep an eye on their fields to help nip this in the bud before an infestation can occur. (Photo by Bruce Potter)


Palmer amaranth can grow 2 to 3 inches a day, typically reaching 6 to 8 feet, or more, in height. Left uncontrolled, a single female Palmer amaranth plant typically produces 100,000 to 500,000 seeds. It is resistant to multiple herbicides.

It has been found in 28 other states, including Iowa, South Dakota, and Wisconsin.

“Palmer amaranth infestations have caused substantial yield losses and greatly increased weed management costs in cotton, soybeans, and corn in the southern states,” said Extension agronomist and crops leader Jeff Gunsolus. “This is a disconcerting, though not completely unexpected, discovery in Minnesota. We have been discussing proper identification procedures with crop consultants over the last three or more years.”

Close-up of Palmer amaranth

Palmer Amaranth has been found in Minnesota fields and it’s important for farmers to watch their fields in order to avoid an outbreak in farm fields across the state. (Photo by Bruce Potter)


Extension and MDA officials commend the grower and crop consultant who quickly contacted Extension after discovering a suspected Palmer amaranth plant. The weed is on MDA’s prohibited-eradicated noxious weed list, requiring all above- and below-ground parts of the plant be destroyed. Transportation, propagation or sale of the plants is prohibited.

MDA and Extension continue coordinating action steps to address the weed.

The MDA is investigating how the weed may have been introduced to the state.

In August, an Extension blog updated steps for both prevention and management at

Further information is available at

Blog Post: Science, Emotion, and the GMO debate

250px-Monsanto_logo.svg5. @FarmBureau @agricaster the truth behind gmos is that they take away the farmers fundamental rights….

4. @FarmBureau @agricaster environmental companies are fighting gmos to make money..? No Monsanto is pushing gmos to make money….

3. @FarmBureau @agricaster why is it that Monsanto does not have to undergo 3rd party testing?

2. @FarmBureau @agricaster if you would like the viewer to develope an onion give them view from both sides not just a slanted perspective…

1. @FarmBureau @agricaster  this is pro gmo propaganda….

There is something going on here that I don’t understand.  This is a series of  Twitter responses to the story I wrote on GMO’s here about a week ago.  It’s from someone with the handle Death to Monsanto, or @gmomgtg. Let’s talk about these responses.

First of all, “Death to Monsanto” isn’t a credible way to get attention.  How about, “The Truth about Monsanto,” or “What Monsanto isn’t telling you?” Death to Monsanto makes you sound like a gun-toting radical who’s looking to get into the corporate office and start mowing down any human beings you can find.  Not okay.

1. “This is pro GMO propaganda” was the first response.  Okay, if it’s just propaganda, tell me why?  What makes your stand against GMO’s any less propaganda and more believable science?  Please, be specific.  I’d like to know the truth.  It’s what journalists are SUPPOSED to do for a living, in spite of the fact that most of my colleagues seem to have forgotten this.

It’s hard to know what the truth is about GMO’s if you don’t farm for a living.  That’s why Ag has to step up and speak up for their industry. (Photo from

It’s hard to know what the truth is about GMO’s if you don’t farm for a living. (Photo from

2. “..give them a slanted prospective.”  I reached out to an organization called Friends of the Earth, who had a lot to say in an email, but I didn’t hear back from them.  I can’t talk to people who won’t call back or email me.  After all, I do work under deadlines.  I’d have no problem if Death to Monsanto wanted to be my interview guest and fill me in on the evidence that GMO’s are a threat to our health.  After all, I have kids that like to eat, and as their parent, I don’t want to feed them stuff that’s bad for them.  Duh.

3. “…3rd party testing.”  Now that’s interesting to me, and something I didn’t know.  If it is true, tell me WHY.  That tweet caught my attention.  Don’t make accusations and then not back them up with the facts.  It ruins your credibility.  Anyone can make accusations without supporting facts, and there’s a lot of that type of crap going up on the internet.  By the way, do folks reading this know the internet is NOT regulated, and folks can post anything they want?

4. “…make money?”  Do you watch the news?  There are people in this country who make a whole lot of money by being professional “conflict entrepreneurs.”  It’s their way of staying in the news and staying relevant.  See Al Sharpton for proof.  And I have to ask:  when did it become a CRIME to make money?  You see politicians on the news bemoaning how the rich don’t pay their fair share?  Why don’t you check THEIR bank balances?  Those politicians have their hand in the proverbial cookie jar, and they’ve made and hid their share of money too.  That, my friends, is the ultimate hypocrisy, and it’s rampant in Washington.  It doesn’t matter what your political affiliation is, either.

5. “take away farmers fundamental rights?”  Please tell me how, because that’s something I’d like to know.  The other side of the issue showed me how it SAVES farmers money by lowering the cost of inputs, for example.  Can you give me an example of how it takes away farmers “rights?”  I’d sure like to know more about that, if it’s true.

In short, don’t make accusations and not back them up with facts.  That’s all I’m asking, and I don’t think I’m expecting too much.  I’m not looking for a verbal smackdown, because that’s the strategy of folks who have no science or facts of any kind to back up their position in a debate, so they just shout you down.  Show me science that proves GMO’s are something I need to be worried about.  I’d like to know.