DATE: 10/24/2005

CONTACT: Vaughan Spearman, (843) 726-3461

EDITOR: Tom Lollis, (803) 284-3343, ext. 241

Plants from Asia don’t belong in U.S. gardens

CLEMSON – Attention American homeowners, landscapers and gardeners! Some plants just don’t belong in your garden.

Many species from China, Japan and other areas in Asia have become environmental nightmares in the United States, according to Vaughan Spearman, area forestry/wildlife agent with the Clemson Extension Service in Jasper County.

“Kudzu (Pueraria Montana) is the perfect example of what is called an ‘invasive species,’” he said. “The ‘vine that ate the South’ was brought into this country by the federal government for practical purposes, to control erosion. It just got out of hand.”

Kudzu can shade out tall trees. None of the natural pests or diseases that would control kudzu in its original environment exist here to control its spread. Growing conditions are favorable for the vine because the United States occupies approximately the same latitude as the area it came from. The seasons, photoperiod and climate are comparable.

“Many of our problem invasives, like Dutch elm disease, were brought to the new world by immigrants. The disease is spread by a bark beetle which entered the United States in a shipment of furniture in 1926. It soon wiped out the American elm,” said Spearman.

“Problem plants are still arriving,” he said. Garden plants from Asia or South America pose a significant threat to gardens and natural areas. Plants like timber bamboo (Phyllostachys bambusoides), and Chinese and Japanese privet (Ligustrum spp.) were first brought to this country by rich plantation owners eager to show off their wealth by traveling to foreign lands and bringing home amazing new plants.

“Timber bamboo, spreading with rhizomes, will completely eliminate all competing vegetation, and the patch can double in size each year if it is not carefully controlled,” said Spearman.

He said that Chinese privet has already choked out much of the bottomland hardwood forests in this country. In some areas nothing grows but this common garden hedge.

Spearman recently took a self guided tour of one of the popular plantation gardens near Charleston. He found a newly invading population of Chinese parasol tree (Firmiana simplex).

“The garden staff told me that the area had developed within the last three years, quickly engulfing a forest of rare American beech (Fagus grandifolia) that used to cover the site,” he said.

Spearman also found other invasive species such as timber bamboo and Chinese and Japanese wisteria (W. sinensis and W. floribunda), choking trees and covering several areas unchecked. He also noted large areas of English ivy (Hedera helix), large maintained hedges of privet and Eleagnus spp., all invasive species and all producing fruit with seeds being spread by wild birds.

The garden also contained a large number of Chinese tallow trees (Triadica sebifera), a huge problem in marsh and wet forest areas. The property also exhibited Sacred Bamboo, or Nandina (Nandina domestica), a common problem at old home sites.

“The worst problem was not that the garden was doing so little to control these problem plants, but that they were selling each and every one in the nursery, with not a one labeled as a potential problem,” said Spearman.

Except for the parasol tree, each of the plants he found at the garden is listed on the Federal noxious weed list, as well as the state invasive species list.

Spearman encourages South Carolina gardeners and landscapers to learn more aboutinvasive species. One way to do that is to stop by the local Clemson Extension office and request a copy of “Nonnative Invasive Plants of Southern Forests” by James Miller. The free publication may also be obtained by writing the U.S. Forest Service’s Southern Research Station, P.O. Box 2680, Asheville, NC 28802.

“Gardeners can help control this problem by not buying or growing any of the species listed in this book,” said Spearman. Parasol tree and Bradford pear (Pyrus calleryana) are not in the book, but they are also very invasive and are listed on the state invasives watch list. You can find more information about the list at: http://www.seeppc.org/southcarolina/SClist.pdf.

“Try to find native or sterile substitutes for these plants, and encourage your favorite nursery to do the same,” said Spearman.

END