Greenbriar, also called cat briar, is a woody vine that will cover everything in its’ vicinity. It has thorns and wraps around trees, shrubs, fences, and any other support available. Because it has very waxy leaves, most herbicides will not affect it.
Greenbriar native to North America. It is in the genus Smilax, which includes about 12 to 15 species. It is in the Liliaceae family, closely related to Daylilies, Lilies, and Yucca. All of the Smilax are climbing vines.
All of the Smilax plants grow through an extensive underground rhizome system. This means they can pop up yards from the main plant, making it very hard to kill. The plants are either male or female, with the female plants having berries that range in color from black or blue to red when they ripen. Birds eat the fruit while many forest animals eat the foliage and tubers.
Since birds eat the fruit, they spread the seeds throughout their range. This is one reason the weed can spring up in your landscape. When the seed germinates, it starts to develop the large underground rhizome network that lets it spread even further.
Greenbriar can survive in shade and can survive deep in the crown of a shrub or forest. It may spend two or three years developing its rhizome network before emerging from the plant canopy. It then goes up trees, shrubs, and other weight bearing structures. It can completely cover a tree and the weight of the vines may cause the tree to break.
The goal of controlling greenbriar is to send herbicide down the extensive rhizome and tuber network to kill them all. Because of the waxy leaves, this can be difficult. There are a couple of ways that are recommended to kill greenbriar.
First, if you can untangle the greenbriar from the plant or structure it is attached to, you do that and lay the vine out on the ground. Carefully paint the leaves with Roundup. Wait two weeks, then cut the greenbriar at the ground level. This will have given time for the Roundup to reach the roots and kill the rhizomes and tubers.
It is often impossible to disentangle living greenbriar from the trees or shrubs it is attached to. In this case, you must cut every vine at ground level and immediately pain the cut vine with Roundup. The new cut will wick the Roundup to the rhizomes and tubers. This method is very labor intensive because it is vital you cut every vine and paint it with Roundup. Miss one vine and you have left a reservoir of food for the rhizomes and tubers and they will spread again.
One of the frustrating things about controlling greenbriar is that it is likely to reoccur in the same place. If it does so, cut the new shoots and paint them with Roundup. Repeat this procedure until no more greenbriar comes up in that area.