Japanese climbing fern
Native to: Eastern Asia, temperate to tropical
An adventive species that was introduced to Florida as an ornamental plant in the 1930s. It has spread across the SE US from Texas to the Carolinas. It continues to expand its established range and climate models demonstrate that 39% of the US provides suitable conditions.
Habit: perennial vine-type fern, reaching up to 90 feet in length.
Description: The rachis is slender, winding and twining. The sterile pinnae (major segments of the leaf blade) are opposite or alternate on the rachis, triangular in shape, bipinnately compound, superficially resembling miniature fronds of bracken fern (Pteridium). The pinnules (divisions of the pinnae) are pinnate or pinnatifid, with a long and slender terminal lobe. The fertile pinnae are borne on the same fronds as the sterile ones, but they are much lacier in appearance due to the slender, fingerlike lobes of the pinnules. These bear sporangia (spore producing structures) in double rows under the margins.
Distribution in Florida: reported from all counties in Florida except Monroe with densest infestations occurring in the panhandle through North and Central peninsula.
Grows in sun or shade, damp, disturbed or undisturbed areas including floodplain forests, wetlands, and pine flatwoods. Its tiny spores are readily dispersed by the wind and easily hitchhike on clothing, equipment, and vehicles. It can grow so dense that it forms a living 'wall', leading to the elimination of seedlings and other native vegetation. Economically, it is a major problem in pine plantations, causing contamination and harvesting problems for the pine straw industry. It also disrupts natural and prescribed fire by acting as a ladder fuel facilitating fire reaching into the tree canopies.
Since the microscopic spores are easily transported via clothing, wind and possibly water, contamination is a constant threat. Control measures should be employed when the fern is not producing spores, which occurs in the late summer/early fall. If control measures must be employed during spore formation and dispersal, then these areas should be treated at a time when workers will not be traveling to other sites in the same day. Take care not to drive equipment through the fern foliage, as this will also help to minimize spore movement. Thoroughly decontaminate clothing, equipment, and vehicles.
More research needed.
Machinery can be used to remove the large mats of foliage that form over vegetation in areas where compaction is not a concern.
A rust (Puccinia lygodii) of Lygodium spp. in greenhouses is being looked at as a biological control agent to control Japanese climbing fern, although many of the biological control efforts are focused on old world climbing fern (Lygodium microphyllum). More studies are being done to determine the efficacy of other biological control agents for Japanese climbing fern.
Best results have been reported using glyphosate, imazapyr, and metsulfuron methyl, herbicides that inhibit the formation of amino acids in plants. Learn more: Biology and Control of Japanese Climbing Fern