Forestry
Useful Links
University of Florida Sites
Other Sites
Division of Forestry
University of Florida Publications
Fern Threatens Pine Straw Industry
Pine straw producers in North Florida are facing a new threat from the non-native invasive plant species called Japanese climbing fern (Lygodium japonicum). The Japanese climbing fern is a perennial climbing and twining, vine-like plant, native to tropical and subtropical areas of eastern Asia and Australia.
The species was brought to the U.S. in the 1930s for ornamental purposes. The widely creeping plants often form mats (Figure 1) and become shrub- and tree-covering infestations. Stretching from slender rhizomes, the vines can climb along tree trunks up to about 20 feet (Figure 2). Within Florida, Japanese climbing fern is distributed throughout the panhandle and south to central Florida. The plant has been found to invade Florida’s natural and managed forest areas alike.
While Japanese climbing fern threatens native biodiversity in our forests, it also has been increasingly a nuisance for private landowners and pine straw producers for the past 5 years. Dense infestations of the species covering the ground between the rows of trees limit or deny access to fallen pine needles, making collection of pine straw difficult or impossible.
Whenever producers attempt to harvest pine straw despite infestation, the mulch is likely to become contaminated with fern fronds and/or spores, which can potentially contribute to the spread of the species. Fronds of the species were discovered earlier this year in pine straw shipped to clients in North Florida. Japanese climbing fern is on the list of prohibited plants (Florida Department of Agriculture and Consumer Services’ Rule 5B-57). This means that any sale, transport or movement of any part of the plant is prohibited.
Florida Department of Environmental Protection (DEP) and other state agencies including University of Florida’s IFAS initiated research and demonstration trials to develop ways of coping with this new threat to Florida’s biodiversity and pine straw industry.
Early trials by the Florida DEP and Northwest Florida Water Management District indicate that glyphosate containing herbicide Rodeo at 1.5% concentration (0.8% of active ingredient) was the most effective for long-term control of Japanese climbing fern (79% mortality at 315 days after treatment). Garlon 3A at 5% concentration showed the best short-term results (100% fern mortality at 42 days after treatment). Garlon 4 at 5% concentrations was the least effective of the three herbicides tried in this study.
Further DEP trials are underway in Hamilton and Calhoun Counties with Accord, Garlon 4 and Vetran 720 herbicides. Research being initiated by IFAS will address spore viability, pine straw contamination and other issues related to potential spread of the fern, in addition to measures controlling fern infestations in pine stands.
Read the Japanese Climbing Fern profile at the Center for Aquatic and Invasive Species Web site.
-- Written by Dr. Jarek Nowak
