Smilax rotundifolia, commonly called roundleaf greenbrier, may be seen climbing up fence posts or wrapping itself around your favorite ornamental shrub. It is one of several species of Smilax but the only one Trimec lists on its label as being effective in killing. Suited to U.S. Department of Agriculture plant hardiness zones 7 to 10, roundleaf greenbrier is native to Florida -- though it is not considered an invasive vine there, it can be hard to keep in check, even with herbicide. Control it by digging up bulbs or spraying it with herbicide.
A Thorny Vine
Reaching heights up to 20 feet, roundleaf greenbrier is a fast growing evergreen vine with round, shiny leaves and stems with prickly thorns. In the fall it puts out deep purplish to black berries which are a food source for wildlife. It prefers filtered shade to part sun, requires an adequate amount of water and is used in some parts of the country as a Christmas decoration. It grows from a cluster of underground bulbs, sending out new shoots if one dies, so it may take more than one application of Trimec to kill this vine.
Smilax Growing in Turf?
Trimec Classic is a selective herbicide that contains the active ingredient dimethylamine salt of 2,4-dichlorophenoxyacetic acid. Apply it directly to roundleaf greenbrier after it has emerged from the ground. Is it designed not to harm warm- or cool-season turfgrasses, so you can spray roundleaf greenbrier growing in your turfgrass without injury to the turf. Mixing ratios vary based on the type of turf. Treat 1,000 square feet of zoysiagrass (Zoysia spp.) by mixing 1.2 ounces of Trimec Classic to 1/2 gallon of water. Apply when roundleaf greenbrier is actively growing. You can apply two broadcast applications twice a year, 30 days apart. Trimec Classic is not suited for use on some grasses like carpetgrass (Axonopus affinis).
A Trimec for Senisitve Grasses
The Trimec Southern formula contains less dimethylamine salt of 2,4-dichlorophenoxyacetic acid than Trimec Classic, so it can be used on warm-season turfgrasses in the southern United States during the heat of summer with less chance of injury to turf. When roundleaf greenbrier is actively growing and grass has emerged from dormancy, mix 0.25 ounce Trimec Southern to 10 gallons of water to treat roundleaf greenbrier growing in bermudagrass (Cynodon spp.) or fescues. This will treat up to 1,000 square feet. If a second application is needed, wait at least three weeks before reapplying. Do not apply more than the recommended rate on the label or injury could occur to your turfgrass.
Both Trimec formulas are corrosive, with Trimec Classic causing irreversible eye damage, so wear eye protection whenever handling these herbicides. When working with either herbicide, cover exposed skin with long sleeves and long pants, and wear chemically resistant gloves. Do not spray where drift can land on water or vegetable plants you intend to eat. Do not allow herbicide to run off into a body of water because it is toxic to fish. Trimec Classic and Trimec Southern are not available in all states, and some states may require a license to purchase or apply the products.
- PBI Gordon Corporation: Trimec Classic Label
- W. P. Law Inc.: Trimec Southern Label
- University of Florida IFAS Extension: Controlling Weedy Vines in the Landscape
- Online Plant Guide: Smilax Rotundifolia
- Cornell University Cooperative Extension: Crop and Pest Management Guidelines
- University of Arkansas Research and Extension: Flower and Garden
- Texas A & M Extension: Carpetgrass
- Photo Credit Brand X Pictures/Brand X Pictures/Getty Images