Stilt Grass is in Bloom

I have been watching my invasive Japanese stilt grass, Microstegium vimineum, to try and cut it down it before it started blooming.  On Sept. 2 I noticed that just about every plant starting to bloom.  (I am in zone 7a, so if you are in a cooler zone, this may be happening very soon in your area.)  My plan was to weed whack it down just when the flowers were forming so that it would not have time to regrow new flowers and set seed this season.  Since stilt grass is an annual, if I can deplete the seed bank, I should be able to bring it under control.  Several references agree that Microstegium seeds remain viable for up to 7 years.

Japanese Stilt Grass in bloom

One nasty feature of this grass is that it also has a set of self-fertile flowers hidden down in the stem.  These are known as cleistogamous flowers.  So it is necessary to cut these off as well as the upper exposed flowers at the stem tips.

A cleistogamous flower in the stem about 4 inches off the ground.

On Sept 3 I used my gas-powered string trimmer to cut down all the plants I could find growing in the woodland edges.  I made one pass to cut the tops and a second pass closer to the ground to go after the stem flowers.  Cutting the plant in smaller pieces may reduce the likelihood of an fertilized seed from maturing (I sound like a lawyer).  In some areas I found that the stilt grass would bend over, rather than getting cut on the first pass.  So the second low pass was really needed.  Where ever possible I tried to avoid any natives I saw.  These included some Panicled Tick Trefoil, Jumpseed and some, as yet unidentified goldenrods.

For some smaller areas, with other species mixed, in I hand pulled the plants.  Since stilt grass has relatively shallow roots, it comes up more easily than perennial grasses and herbs.

If I can keep this up for a few more years I may be able to eliminate scenes like this:

Stilt grass has filled area to left.  Area to the right is less disturbed
(unmown) and shows less invasion by the stilt grass.