It would be nice if the growth of Japanese stiltgrass, Microstegium vimineum, would wait until we were done dealing with garlic mustard for just a little while, but I have seen signs of it germinating here (Central Maryland) in early May. So now is a good time to take a look at how some of the steps I've been taking to get rid of this invasive grass are doing.
This is what a shady, unmanaged area looks like. The arrows are pointing to areas with a high density of stiltgrass seedlings. Also present are plantain, dandelions and violets. |
In the areas treated with the pre-emergent herbicide, Dithiopyr ('Dimension'), I've noticed little to no seedlings of stiltgrass, or other plants for that matter. Reflecting back on the timing, I should have waited until mid-April to apply this material so as to let some of the cool season grasses get started. But it's hard to predict when a warm snap will come along and mess everything up. I |
This area was treated with a pre-emergent herbicide, dithiopyr ('Dimension') at the end of March. I was not able to spot any stiltgrass seedlings in this area. Other plants here are clover, Indian strawberry, and purple lamium. |
One of the most dramatic results was where I used a lawn torch to burn off all the surface vegetation in late summer last year when the stiltgrass was in flower. A few perennial grass plants bounced back after a week, but it was necessary to reseed the area to provide cover for the soil. As I mentioned awhile back burning seem to be most effective in the fall prior to the seed ripening/dispersal. Burning also eliminates the cleistogamous seeds found low on the stem. Burning after seed is dispersed is too late and spring burning just opens the group to germination from the existing seed bank (see this report from the Forest Service.) The burned area seems completely free of stiltgass, as well as some other weeds while the control area is dense with stiltgrass seedlings. |
Here is a comparison of an area that I burned with a yard torch in late summer last year (right side) with an control patch where nothing was done. The burned are was overseeded with a tall fescue blend, nothing for the control. Arrows indicate dense patches of stiltgrass seedlings. |