Q: In our development, we have Japanese stilt grass around a retention pond that I will be trying to deal with this year. I was hoping to get some practical advice on dealing with it. It’s too big a project for me to do by hand pulling alone (it’s about 1000 linear ft. around the pond). We planted Juncus effusus around the pond the previous fall, but the stilt grass covered everything last summer/fall.
A: The best way to deal with Japanese stilt grass is pre-emergents. Stilt grass germinates earlier than crabgrass so pre-emergents need to be put down by mid February. Any pre-emergent that’s labeled for crabgrass should work for stilt grass also. Corn gluten should work if you want to keep it 100% organic and the extra nitrogen won’t be a pollution problem. I suspect that even though the corn gluten is a shorter term control than others like, Snapshot or Preen, it will last long enough since stilt grass doesn’t have an all season germination period like crab grass.
If you have any stilt grass that does germinate (you will the first year) don’t pull it but rather spray with Roundup or clip the stem just below ground level so as not to pull out a plug of soil (and with it the pre-emergent protection). Once you get a hand on the stilt grass you need to keep the area covered with mulch or a ground cover. The Juncus effusus will work where it’s thick enough but that might take a couple of years of pre-emergent treatments.