Japanese climbing fern (Lygodium japonicum) is a non-native, invasive vine which was introduced as an ornamental plant around 1900 and has become naturalized through the Southeastern Coastal Plain from the Carolinas to Texas.  It is native to East Asia, the East Indies, and Australia.  The plant occurs as scattered individuals to tangled masses of dense canopy which can eliminate the underlying vegetation and overtop small trees.  The climbing, wiry vines may girdle small diameter shrubs and tree saplings, representing a threat to bottomland hardwood reproduction.  The fern is also common in established stands of southern pines, and movement of the fern through dissemination of commercial pine straw is a concern.  It can be problematic during prescribed burning as a fuel ladder to canopy trees and is not controlled by the use of fire.  As is typical of invasive species, it reproduces prolifically by rhizomes and spores.  Spores are extremely numerous, long-lived, and readily disseminated by wind, water, animals, and machinery.  Few studies have documented distribution, site factors affecting the occurrence of the species, or effectiveness of control measures.

Results/Conclusions

In Florida forests, Japanese climbing fern is most abundant in forest sites of the panhandle and North Florida.  Site hydrology is very important to the occurrence of this plant, which is suited to hydric conditions.  The forest litter layer of pine stands appears to provide an environment fostering occurrence of the fern even where soils are well-drained.  The fern is also common in the understory and mid-story of bottomland hardwood forests having high soil organic matter and good moisture holding capacity.  The area infested by Japanese climbing fern appears to be increasing, but there is a need for research to determine the species distribution and to predict new infestations.   Herbicides which inhibit the formation of amino acids in plants, specifically glyphosate, imazapyr, and metsulfuron have shown the most promise for direct control.  Metsulfuron provides the best selectivity with respect to minimizing impacts to associated vegetation, and many native grasses of the region are tolerant to the herbicide.  Imazapyr provides lasting control but may be absorbed by the roots of associate vegetation and the potential for injury to hardwood trees is a concern.  Glyphosate is effective in controlling the fern, but associated vegetation will be adversely effected if sprayed.  Herbicide control measures should include products with different modes of action to mitigate the development of herbicide resistance.