Hi everyone,
As I gear up for another summer of battling black swallow wort, I thought I'd share what I've tried so far. Last year I was able to control isolated patches of swallow wort by using Round Up poison ivy killer (contains small amounts of triclopyr) by spraying each plant until dripping. I was using 8 ounces of the concentrate in my 1.33 gallon battery sprayer with a bit (maybe 2 oz, I didnt measure) of 80/20 surfactant from tractor supply. That works well for individual plants.
Now, I'm back to tackling my giant monoculture. I obtained some used billboards and put them down mid May. I tried sailing grommets with 4 inch landscaping pins, but that didn't hold. I needed something heavier. I've moved to rocks and milk jugs, which I need more of. The billboards seem to be suppressing growth, but I think being that they're white, they're still letting too much light through. I'm going to get more and double up with two layers. The portions of the photos that show no growth is due to the billboard being blown into a tangle from last winter.
I just wanted to share since I know many of us are struggling to get this terrible invader under control.