What exactly are invasive species? Are they from outer space?
UGA’s Center for Invasive Species and Environmental Health defines invasive as any species including its seeds, eggs, spores or other biological material capable of propagation that is not native to a given ecosystem and whose presence causes environmental harm or harm to human health. That is some definition.
A shorter definition would be plants and animals that do not belong here and are taking over the environment. Two good examples that come to mind readily are the kudzu vine and coyotes.
According to the Fish and Wildlife Service, invasive species cost more than $120 billion to control. The wooly adelgid, another import, is devastating the eastern hemlocks in north Georgia.
There are numerous invasive plant species in the southeastern states, at least 263 at last count. Some of the most common trees in our area that are invasive are the chinaberry tree and the Bradford pear. Both are common in our fence rows.
The mimosa and tallow tree (popcorn tree) are two more that are seen in our landscape. We’ve identified the trifoliate orange tree that has tractor tire penetrating thorns growing here in Troup County. It produces a small bitter orange that ripens to a golden yellow color.
The paper mulberry was brought here in the mid 1700’s as a rapidly growing shade tree. It is now widely dispersed throughout the state.
There are numerous shrubs that are invasive as well. The aromatic bush honeysuckle and privets are two that you might think were native due to their prevalence in the landscape. The Chinese privets have the smaller leaves and the Japanese (ligustrim) privets have larger, leathery leaves.
Nadina, leatherleaf mahonia and autumn olive (elaeagnus) were widely planted ornamentals that have moved on to forest edges and open forests.
Japanese honeysuckle, an unwelcome relative of the bush honeysuckle, kudzu, non-native wisteria and all the periwinkle varieties are very common invasive vines. The invasive grasses include bamboo, cogongrass and Johnson grass.
Removing these species from the landscape can be a real headache. There are six species of invasive ferns and 46 species of invasive aquatic plants.
So, how did all this happen?
Many well-meaning folks decided to improve upon Mother Nature. They brought plants from other parts of the world that they thought would improve the landscape. Others brought in plants that would solve the erosion problems such as kudzu.
Somebody had the idea that we should build natural fences which are called hedge rows in Europe. What they didn’t consider was the biological factor. How do they reproduce and how are their seeds dispersed.
Plants with colorful or tasty berries are readily consumed by birds and deposited elsewhere. You’ll see plenty of invasive plants at the base of trees where the birds make a rest stop.
Some plants spread by underground stems called rhizomes such as bamboo, congongrass and Johnson grass. These may be carried from field to field with field equipment and soil when the rhizomes are picked up by the equipment. They can be some of the toughest plants to get rid of, just ask someone who has bamboo or Johnson grass growing nearby. They may also reproduce by seed which causes further problems.
How do get rid of these pesky invaders?
The first step is not to plant them in the first place or allow them to take root. At the home place we allowed a mimosa to volunteer. After about seven years we had baby mimosas popping up everywhere.
I am constantly pulling up seedling privet. Many homeowners plant dwarf nandina. They have beautiful berries that birds carry throughout the yard. An autumn olive (elaeagnus umbellate) has established a foothold as well.
Keeping an eye out for invasive species and pulling them up when first identified is a good start. Be careful about using straw as mulch. Many invasive seeds may be harbored there.
Good equipment sanitation can prevent transfer of invasive species from yard to yard. Eradicating invasive species may take a lot of persistence and sweat equity. Using multiple approaches such has mechanical destruction and herbicide treatment. It may take several attempts.
On tough invasive plants such as cogongrass, call the Georgia Forestry Commission. Cogongrass is a federal noxious weed and any occurrence should be reported. For the UGA herbicide recommendations, call me or stop by at the extension office.
Brian Maddy is the ANR Agent for Troup Cooperative Extension. The Troup County Extension office is located at 114 Church St. in LaGrange and may be reached at 706-883-1675, Monday through Friday, 8 a.m. to 5 p.m.