Johnsongrass was introduced in 1830 as a forage crop and for stabilizing ditches. It grows up to 8 feet tall and can produce up to 80,000 seeds. Johnsongrass crowds out desirable plants and destroys food and shelter for birds and other wildlife.
Johnsongrass is an invasive grass that knocks out habitat for wildlife and causes trouble for farmers and ranchers. It grows up to 8 feet tall and resists many control methods. Here's an overview of your most effective methods.
As with many weeds, pulling out Johnsongrass by hand can break the roots. Those broken roots can simply grow back. The same is true with hoeing or tilling.
Before the weed produces a seed head in July, apply a broad-spectrum product such as Roundup® Weed & Grass Killer. It goes down to the root for effective control. Just be careful not to spray it on the plants you like, since it's a non-selective herbicide and will harm the plants in comes in contact with.