The first thing to discuss is the big question - what is an invasive plant? According to the Alabama Invasive Plant Council an invasive plant species is one that displays rapid growth and spread, establishes over large areas and persists. Invasiveness is characterized by robust vegetative growth, high reproductive rate and longevity. Even some native plants can become invasive under the right conditions.
There are literally thousands of species of invasive plants in the United States and we have more than our share in Alabama. As is so often the case, we have brought most of the problems on ourselves. Many were brought for erosion control, livestock grazing, wildlife habitat improvement and as ornamentals for our landscapes.
A question many people ask is why does a perfectly well-behaved plant (in its native habitat) go berserk in their new home? Although the reasons can be varied and quite complex, in general, the new plant lacks the natural controls present in the plant’s native habitat. Sometimes, we use this to our advantage by finding the native pest of a plant and introducing it to our area. This has been done with a non-native musk thistle that has become a serious problem in pastureland and roadsides. A small weevil was found on the thistle in its native land and was subsequently imported and introduced on the musk thistle in our area with good results. Of course anytime a biological control is introduced, we are always concerned the control will become a pest itself. Because of this fear, these organisms are tested as thoroughly as practical to make sure this doesn’t happen.
The 10 worst plants identified by the AIPC, in no particular order: kudzu (you knew this one was there), cogongrass, tropical soda apple, tallowtree (popcorn tree), Chinese privet (I hate it), Japanese climbing fern, invasive roses, hydrilla, Eurasian water milfoil and alligator weed. The last three are aquatic plants threatening our lakes and streams.
As mentioned above, I hate Chinese privet. I have large patches of it on my property and I have tried multiple methods of control. The first method I tried was to fence the area and let the goats eat it. The goats ate every last green sprig on every plant. I had to move them to another area so they would not starve and within a few weeks the privet was growing in this new area that was previously uninvaded. I am through with this natural control measure. My newest assault is to repeatedly cut the plant down and treat the fresh wound with glyphosate herbicide. This is going to take a long time, but at least I don’t have to keep catching the goats which also liked my neighbor’s shrubbery equally as well as the privet. Another approach is to treat the lower portion of the trunk during the fall or winter with an appropriate herbicide. The most effective treatment during this time is a basal spray on the smooth wood of small trees from the ground up to 18 inches high. The optimal timing for application is late fall to early winter when nights are cold, but day temperatures rise into the 50s and 60s. For details on control options, visit this web link: http://tinyurl.com/privetcontrol.
Also, the Alabama Cooperative Extension office in Cullman County will be hosting a meeting called "Controlling Invasive Plants Now" on November 13. For details and to register, visit www.aces.edu/cullman and click on the "Meetings and Events" link.
Tony A. Glover is a County Extension Coordinator in Cullman County.