First invasive plant recorded in Missouri found near Dexter

Lori Amos
The Rolla Daily News
Alligatorweed (left) can dramatically reduce habitat for wildlife and fish, interfere with boating and recreational use, and even make flooding worse.

The Missouri Department of Conservation said immediate steps are being taken to eradicate an invasive, non-native aquatic plant known as Alligatorweed, recently found at Otter Slough Conservation Area. 

According to the department in a news release Tuesday, if the Alligatorweed — native to South America — is not eliminated, the fast-growing plant could suppress desirable native wetland plants, which will harm wildlife and fisheries habitats. 

Invasive plants are aggressive, non-native species whose presence causes or is likely to cause economic harm, environmental harm or harm to human health.

The department’s fisheries management biologist, Mike Reed, said the plant grows quickly, forming dense mats that crowd out native species. The invasive plants grow in or along streams, ponds, lakes, ditches and wetlands. 

According to Reed, this is the first time the plant has been recorded in Missouri, although it is found in several southern states. 

Reed said, “We believe the plant was introduced inadvertently by boat, motor, or trailers of waterfowl hunters who had been in southern states such as Arkansas or Louisiana, which have a lot of this plant.”

“The plant spreads by stem fragments very readily,” Reed said.

He said the Alligatorweed can drastically reduce habitat for wildlife and fish, interfere with boating and recreational use, and even worsen flooding. 

The Department of Conservation has implemented a treatment plan to combat the issue by eradicating the plant from Unit 31 at Otter Slough and preventing it from colonizing additional units at the conservation area. 

“Unfortunately, Unit 31 at Otter Slough is being held out of the waterfowl hunting program this fall to allow the unit to be held dry in an attempt to kill remaining alligator weed,” Reed said. 

He said the plant is controlled successfully in southern states using EPA-approved aquatic herbicides and biological control using a beetle specific to the plant. 

The herbicide has been used on the Otter Slough alligator weed population, Reed said. 

But unfortunately, Reed said the beetle couldn’t be used in Missouri because it would not survive the winter. 

To learn more about invasive plants in Missouri, visit mdc.mo.gov. 

Alligatorweed grows quickly, forming dense mats that crowd out native species. These invasive plants grow in or along streams, ponds, lakes, ditches, and wetlands.