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7 ft. tall 'super weed' threatens crops in Upper Midwest

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A tough new weed is threatening to crush crops across the Upper Midwest, and a lot of farmers are worried. The “super weed,” palmer amaranth, is highly resistant to herbicides and grows so tall and thick that it can stop combines in their tracks.

Scientists confirmed that palmer amaranth has been found in Iowa and in a few farm fields in South Dakota. It hasn't reached Minnesota or North Dakota yet, but those states are on high alert, according to the Associated Press.

In fact, Minnesota and North Dakota are the only two states where it hasn't been reported yet, according to
Rich Zollinger, North Dakota State University Extension weed specialist. And once the weed gets a foothold, it's virtually impossible to get rid of, said

It can overrun a farm field in just a few years and crowd out crops like corn and soybeans.

“If you think you find plants — kill it!” said Zollinger, according to the AP. “Don’t even think. Just kill it.”

Palmer amaranth, also called "carelessweed," is native to the desert Southwest and northern Mexico, and is now widespread in Southern states. The plants can get to be 7 feet tall, and the stems can grow as thick as baseball bats.

The photo below shows palmer amaranth plants growing between rows in a cornfield.

It also spreads quickly, because each plant can produce as many as a million seeds. Once established, it's incredibly difficult to eradicate because the plants have developed a resistance to many of the most common farm herbicides.

The best defense against the weed is a good offense, as the saying goes. Zollinger says farmers need to be on the lookout at all times for palmer plants, and if they find any they should get rid of them immediately.

They also need to be careful not to transport seeds from the plants on their farm equipment from one field to another.

One possible weapon in the fight against palmer amaranth is the cold winter weather in the Upper Midwest.

Ag researchers in South Dakota plan to keep a close eye on the site where palmer amaranth was found to see if any seeds survive the winter, the Associated Press says. Seeds have not survived cold winters in the past, according to Paul Johnson, extension weed science coordinator for South Dakota State University.

“The weed does have the ability to change. Maybe that will be the change it makes — adapting to a northern climate,” Johnson said, according to the AP.

Herbicide manufacturers are also working to come up with new types of farm chemicals that will be more effective against the plants.

As for Minnesota and North Dakota, Zollinger says it's just a matter of time before palmer amaranth reaches those states, too.

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