Feb. 11, 2011

Japanese knotweed (Fallopia japonica), giant knotweed (Fallopia sachalinenis), and their cultivars and hybrids on Friday were announced as Nebraska's newest noxious weeds by Greg Ibach, Nebraska Department of Agriculture director. Control of designated noxious weeds is mandated by state law.

Knotweed has been found in 42 states, but currently is in only a few Nebraska counties. 

"This early designation in Nebraska will allow us an opportunity to eradicate the small infestations detected and stop the sale of plants on the ornamental market ," notes a fact sheet of the Nebraska Weed Control Association. "Knotweed has the potential to invade all riparian areas in the state as well as establish in 55% of the state's upland areas that receive more than 20 inches of rainfall annually."

“In order for us to continue being good stewards of the land, we need to work to protect our natural resources from non-native plants that have no value and have the potential to cause damage to our ecosystem if left unchecked,” Ibach said. “This designation in necessary to help county weed control officials work with landowners to address areas of infestation and to prevent the further spread of this invasive species.”

Ibach has the authority to designate weeds as noxious under the Noxious Weed Control Act.

According to Mitch Coffin, manager of the NDA Noxious Weed Program, Japanese and giant knotweed can threaten both open and riparian areas. Plants may spread rapidly and from dense monocultures. In riparian habitats, the weeds can increase the risk of flooding and river bank erosion. Prolific rhizome and shoot growth can also damage foundations, walls, pavement, drainage works, and flood prevention structures.

Other officially designated noxious weeds in Nebraska include: Saltcedar, Canada thistle, leafy spurge, musk thistle, plumeless thistle, purple loosestrife, spotted and diffuse knapweeds, and phragmites. For UNL Extension publications on each of these noxious weeds, visit the UNL Extension Publications website and search for "noxious weeds."

For more information about the Japanese and giant knotweed designations, contact your county weed control superintendent or Coffin at (402) 471-6844.