Source: James Schuster (708) 352-0109 Contact: Bob Sampson (217) 244-0226 Extension Communications Specialist e-mail: rsampson@uiuc.edu

Mowing or trying to pull nimblewill, a grassy weed, only encourages its nodes to sprout, said a University of Illinois Extension horticulture educator.

"This grassy weed can only be controlled with a nonselective herbicide," said James Schuster. "Nonselective herbicides kill most plants that are sprayed. Therefore, only spot treatment of a contaminated lawn is usually recommended."

Nimblewill arrived in Illinois from the South many years ago, he noted. The above-ground plant parts are not cold-hardy and the grass will die back to the ground with the first good frost or freeze of the fall. In the spring, it does not green up till weeks after the Northern grasses have started to grow.

"Nimblewill is a stoloniferous grass," Schuster said. "This means the shoots grow above ground. These stolons grow out from the crown on bare ground and root at any of the nodes along the shoots. The plant has numerous nodes on the shoots and roots and the ability to start new plants from the nodes."

Where there are other grasses, nimblewill grows upward and then flops over by its own weight. The density of the nimblewill shoots tends to help smother other grasses that are mowed short.

"With each mowing, there is a potential for spreading this grassy weed," Schuster noted. "Even bagging the clippings does not stop the spread of nimblewill throughout the lawn or landscape.

"Not all of the nodes are captured in the bag. Some fall to the ground while others stick to some part of the mower and fall off later. Wherever these nodes drop or are blown, there is the possibility that the node will take root and send up a new plant."

When applying a nonselective herbicide to control nimblewill, a border of desired grasses around the weed is generally killed, too.

"This is to minimize the risk of missing any of the active nimblewill," he said. "The nonselective herbicide glyphosate is the product usually suggested for control of this weed. Glyphosate can't kill dormant plants and it does not kill seeds.

"Glyphosate kills through the chlorophyll. Therefore, nimblewill must be green to get control using glyphosate."

Schuster said to follow all label directions and precautions.

"Allow two weeks to make sure the herbicide has a chance to kill the roots before reseeding or sodding," he noted. "Nodes or seeds left behind and not killed often result in more patches of nimblewill in future years."