This cool-season grass is the curse of restorationist!! Its growth is aggressive, it is difficult to eradicate, and it destroys plant diversity by creating a monoculture. Preliminary research shows that there are negative effects on wildlife as well.
The adage, “Know thy Enemy,” is very true in restoration work. At first, I thought this to be a wetland plant, but soon discovered that it can thrive quite well in upland areas. It reproduces by seed and rhizome. It is clonal so the rhizomes are the main growth method with their peak growing time in late summer and a second growth spurt in fall. These rhizomes dominate by creating dense patches of grass or by shooting further away and setting up a new patch of grass. In early spring, it is one of the first plants to emerge and because of its sod-forming nature, native plants are shaded out and outcompeted for resources.
Below is a picture of 2 “clumps” of RCG and a close up of the ligule. When you break the leaf from the stem, this papery sheath, known as a ligule, remains. The only other grass I know of that does this is orchard grass and while that’s not desirable in a prairie, orchard grass isn’t as dominating as RCG.
There is no one right way to remove this. Each person needs to decide whether they want to use mechanical means, chemical means, or some combination of both. There is a thorough menu of options listed on the Invasive Plants Association of Wisconsin (IPAW) website shown below.
Whatever method or methods are chosen, we need to accept that RCG is persistent and tenacious so eradicating it means we have to be as well! I have marked 36 stands in our prairie. Over the last 3 years, I have tried a number of different treatments. Although the patches are not spreading, they aren’t going away either. This year, I’m going to dig up the patches to break up the rhizomes and stimulate the dormant root buds. Once they have resprouted, I’ll dose them with a low dose of sethoxydin mixed with crop seed oil and a small vial of Miracle Gro®. Sethoxydin is a grass-specific herbicide so the surrounding forbs will not be affected. The crop seed oil will help the herbicide to penetrate the tough cuticle of the RCG leaves and the Miracle Gro® will make it want to suck up all that delicious herbicide! One other to note, the herbicide is UV sensitive, so it’s best if it is applied on a cloudy day or early morning. I vow to do everything I can to eradicate it and protect the native plants. RCG has met its match in my prairie!!