Good Weed, Bad Weed
By Lloyd Singleton, Extension Agent II
A Lake county resident recently contacted our Extension office with a photo of a “weed” that she thought looked like the one taking over her shady St. Augustine lawn, wanting to know how to get rid of it. I was easily able to identify the plant in the photo as Oplismenus setarius. The name just rolls off the tongue, right? Well, perhaps you’d prefer to use one of the common names, Woods grass or Basket grass when you refer to this underappreciated, native-Floridian, shade-loving groundcover.
What to do with Woods grass weeds?
Woods grass is appreciated for its tolerance of deep shade and our rainy summer months. By winter, the woods grass will subside. In the meantime, there is no selective herbicide appropriate to use in turf, so I recommended one of these three actions:
- Hire an arborist to appropriately thin the trees and increase sunlight to the area
- Mechanically remove the woods grass where unwanted (weed pulling)
- Appreciate the natural beauty of this native groundcover until winter dormancy
Given my recommendation, the resident looked more closely at the photo she sent, and realized that it was not the weed in her turf after all. She followed up by sending actual photos of the weed, skunkvine (Paederia foetida). If she breaks off a few leaves and crushes them, it should have a strong sulfur-like smell. It is a Category I invasive in Florida and is a bad one!
Skunkvine leaves can vary in appearance depending on where it is growing and the age of the plant. These were fairly young and in a relatively shady spot, probably with a tree or some shrubs nearby that also have skunkvine growing in them; that is where we usually see it growing in turf. It roots all along the stem, especially at the nodes and can become quite woody. When it gets woody, it is more difficult to control.
There are several broadleaf herbicides that can be used for control but the best one would depend on where the skunkvine is growing in relation to other shrubs, trees, or etc. The products available to homeowners change quite often; availability also varies by location and retail vendor. The best thing to do for most homeowners would be to call a lawn control professional to handle it. It will probably take a few applications for complete control and it still might come back, so it is important to maintain an eye on the area once it seems to be gone.
Our UF/IFAS Extension weed specialist, Chris Marble has tested herbicides on skunkvine, and the only ones that have been effective are either non-selective (like glyphosate) or can’t be used in St. Augustine (like triclopyr). He reports that several professional pest control companies have had success with different rates of metsulfuron (Manor, MSM, etc.) but that is a pretty powerful herbicide in terms of what it could do to non-target plants and should only be applied by someone who is trained (although it’s not restricted to just professional use).
The moral of the Good Weed, Bad Weed story? Make sure you know what plant you’re dealing with, and UF/IFAS Extension is here to help. Visit our Master Gardener plant clinic at 1951 Woodlea Road, Tavares, Monday through Friday, 9 a.m. – 4 p.m.