My Nemesis: Japanese Stiltgrass!

Lordy. This stuff is just the biggest flora pest around here. And, at this time of the year, this evil, weedy, grassy pest is going to seed. Ugh.

In case you have not seen it, you may not have a yard, you may not walk on the paths,  and probably don't drive anywhere around where there are is unmowed roadsides. This invasive grass is just taking over where our own grass is supposed to be growing and taking over our native areas. Here is why.

Microstegium vimineum, is an annual grass so its entire life cycle happens in one year. It will germinate, grow and reproduce. Each plant can produce between 100 and 1000 seeds per year. There are no biological inhibitors to this plant as not even deer eat this plant! It can survive in the sun and adapts extremely well to low light levels like what is in the shaded forest floors around here. The plants also root at each node (where the leaf meets the stem) and can spread that way until it is time to flower between August and October.

You may wonder how this plant spreads itself around so well. When I was recently at the Westmoreland State Park in the Northern Neck of Virginia, there was a sign to please wipe your shoes on the bristles provided because the seeds are very sticky and they want to control the spread of the grass. Imagine all the deer, raccoon, dogs and people who walk around or near patches of Japanese Stiltgrass and the potential of leaving with seeds attached to their legs and feet. In addition, the easiest way to spread is through the rain, that is why you will see it around stream beds and runoff areas on highways. Exponential opportunity to spread their reproductive seeds all around the area and beyond. 

In addition, the seeds can stay viable in the soil for up to 5 years! The plants are very shallow rooted and can be hand pulled easily. However, because hand pulling plants disturbs the soil and may expose stiltgrass seed from previous seasons, late season pulling (before seeds ripen on the plant) will avoid the likelihood of seed germination.

Two ways to handle the spread of this lovely, light colored, lanceolate shaped leaved plant:

~ Mow the plants down in the fall BEFORE the seeds are set. BAG the grass when you do this so the potential seeds are removed from your yard. 

~ If you feel confident that your spray will not drift, you can use a spray with the active ingredient of glyphosate (Round Up). It is systemic and kills on contact so you may have some collateral damage. Be careful.

~ Use a pre-emergent crabgrass killer in early spring and again in mid-summer as the treatment only is for 3 months! I have used an organic, Corn Gluten, and also used Preen, a well known crabgrass pre-emergent. Both work well if used before germination in the spring.   And, if you have it popping up in flower beds like me, the pre-emergent killers will not damage bulbs or perennials. So, feel free to spread it in those beds as well.

So, right now, what can you do?

Mow your lawn. Bag your clippings because the plants are flowering right now.

Begin prepping your lawn with appropriate fall activities:  a soil test, over seed your lawn. Once your grass seed germinates, lime and fertilize as necessary. This will get the roots established before the winter temps drop.  Do this before October 15 for best results in our area.

In March, apply your pre-emergent of choice. By this point, the other grass that you want to grow in your lawn, will be fully established.

Check out this website as I found some good information here if you want more background on this annual grass.  http://www.nps.gov/plants/alien/fact/mivi1.htm

Good luck with your control measures! I will be handling this in my yard where it is creeping into my regular vegetation. I will also be giving my neighbors advice about it again this year. The ones who heeded my advice last year really had nice lawns this year!

In addition, I will attempt to the best of my ability to keep my dog from walking into patches of the grass as we have our daily walks!

I really hate this stuff.