Jane's Garden 7/13/14: Fighting invasive plants

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A concerned citizen rushed into the Dunnellon Public Library one Friday in mid-June to report there was a little old lady pulling up all the lovely ‘Boston’ Ferns from the front entry flower beds. The staff told her this Boston fern was an invasive alien plant and would be replaced by a Florida native species after the infestation was completely removed. The lady then asked the gardener, a volunteer Friend of the Dunnellon Public Library, how to identify the exotic pest plant.

A thorough information pamphlet, SS-AGR-22, titled “Natural Area Weeds: Distinguishing Native and Non-Native ‘Boston Ferns’ and ‘Sword Ferns,’” by Ken Langeland, professor at University of Florida, is available online at http://edis.ifas.ufl.edu. On June 6, Keith Morin at the Department of Environmental Protection in Crystal River Buffer State Park provided the Friends of Dunnellon Public Library with printed copies of 10 circulars so the friends and public could be informed.

“Help Protect Florida’s Natural Areas from Non-Native Invasive Plants,” circular 1204, also by Langeland, explains the basics. As there are similar native ferns, it is important to correctly identify problem plants.

Tuberous Sword, Nephrolepis cordifolia, was first discovered naturalized in Sumter County in 1933. It was then considered desirable. By 1938, it was under cultivation in Floral City. Today it has invaded natural areas from South Florida north to Georgia in hammocks, pinelands, flatwoods and abandoned lots next to cultivated gardens. Many homeowners are still unaware how damaging this alien plant can be.

Asian Sword Fern, N. multiflora, was found to be “driving out all other plants” on Sanibel Island, Lee County in 1954. By 1965 it had invaded Boca Chica in Monroe County. Since the 1990s, this fern has been listed by the Florida Exotic Pest Plant Council, FLEPPC, as a Category 2 invasive. In 1999 it was upgraded to Category 1, as it actively “alters native plant communities by displacing native species” and the wildlife associated with those communities. A complete list is available online.

The tuberous sword fern leaflets, called pinnae, often overlap the central stem, called a rachis. Its roots have brown tubers, about three-quarters of an inch in diameter, growing along them. Dig up the roots, as pulling generally leaves the tubers underground to re-sprout.

Beneath desirable landscape plants, small re-emerging fronds can be killed with a diluted 1.5 to 2 percent solution of glyphosate herbicide. Apply carefully on a windless day, as glyphosate will kill desirable vegetation, too, if it gets on their leaves and translocates to the roots.

Glyphosate strongly combines with soil particles, where it breaks down chemically within weeks. It has not been found to leach through soil into the aquifer, nor does it cause cancer in lab animals.

Always follow the directions on the label. More is not better. The beds and surrounding parklands at Dunnellon Library will need constant monitoring to detect new alien invasive plants that drift in.

Volunteers are needed to remove invasive plants at state, county and municipal parks, and libraries, churches, schools, trails and greenbelts. Sugarmill Woods has a serious problem with alien Skunk Vine. Rainbow Springs State Park has an ongoing struggle to remove Asian and Tuberous Sword Ferns. Read and learn to identify exotic invasives. Prevent aliens by using native plants in the garden. Remove invasive plants from your property. Share this information with friends and neighbors. Together we can make a difference.

Marion County Master Gardeners will host a session about Invasive plants at 2 p.m. Tuesday, July 15, at Dunnellon Public Library.

Jane Weber is a professional gardener and consultant. Semi-retired, she grows thousands of native plants. Visitors are welcome to her Dunnellon, Marion County, garden. For an appointment, call 352-249-6899 or contact JWeber12385@gmail.com.