Old world climbing fern (Lygodium microphyllum) is a plant that originated from South East Asia, Melanesia, Australia, and tropical Africa. It is commonly known as climbing maidenhair fern, snake fern or small-leaf climbing fern. It is an invasive weed that invades open forests and wetlands. In this article we will talk about how to get rid of old world climbing fern.
It was first introduced to the U.S. in the 1960s as an ornamental plant. Once the weed invades an area, it smothers the native plant community in the area. It also interferes with the ecological balance of the ecosystem. The weed also makes forests susceptible to forest fires. This is because of its vines climbing up trees and therefore posing a risk to them in an event of a fire outbreak.
How to identify old world climbing fern
Old world climbing fern has leaf-like parts called fronds which can grow up to 100 ft (30 meters) long. These parts are usually instrumental in the plant’s twining or climbing behavior. This plant spreads over the ground, shrubs and even climbs trees.
Its rhizomes and rachis are usually dark brown to black. The pinnae, which are the leafy branches of the plant, grow from the rachis. They are usually between 2 to 5 inches in length.
The pinnae, on the other hand, contain pairs of leaflets usually known as pinnules. These are usually either fertile or infertile. Fertile leaflets are usually covered by lobes of leaf matter around the leaf margin. This helps in protecting the reproductive tissue.
The infertile leaflets lack elaborate and specialized reproductive systems. Fertile leaflets also have fingerlike projections that contain spores. These are dispersed mostly through the wind.
Underside of leaflets, some produce spores and others don’t.
Natural habitat
Old world climbing fern is mostly found in the moist parts of South Florida. It can also grow in shallow water and dry areas. The plant also likes cypress wetlands, hammocks, floodplains, roadside ditches, and disturbed corridors.
It is usually dispersed by wind and other physical carriers so it has the potential to infest areas far away from the parent plants. The young plants are usually found at the moist buttress of trees. It is an invasive climbing fern which is a non-native plant.
Old world climbing fern invades an area due to its aggressive nature then forms a dense canopy. It then dominates over the native plants and competes with the plants for resources. The plant is estimated to be covering an area of around 200,000 acres of land in Florida. It is considered difficult to get rid of old world climbing fern.
Distribution
Old world climbing fern has spread into many parts of the world because of its aggressive nature. It is native to Africa, Asia, Australia and the Pacific Islands of Fiji and Micronesia. In Florida, the weed has been growing at an alarming rate. It is mostly in South Florida but it is also moving towards Central Florida.
Reports of Old World Climbing Fern in the US
Why is old world climbing fern invasive?
The old world climbing fern competes with other plants for sunlight. This plant climbs trees, forms canopies and can completely engulf the trees. The vine can kill mature trees and smother the undergrowth. This makes the regeneration of the native plant community difficult. As time goes by, the plant forms a thick mat on the invaded land. This leads to a severe alteration of the ecological balance of the ecosystem of the area.
Due to its climbing behavior, it poses a great risk to trees. This is because the plant transports fire. This leads to extensive damage to the trees. The fern is also capable of transporting fire to the wetlands. These wetlands could be used as boundaries to the spreading fire.
How to get rid of old world climbing fern
Old world climbing fern has many effects on the environment. This plant can also invade the residential landscapes and horticultural nurseries. These qualities make it a very undesirable weed which requires control.
There are various ways in which to keep this invasive weed in check so that it can’t continue destroying the environment. Prescribed fire is an effective control method in a specific habitat but can cause colonization by the non-native plants.
Since the ferns thrive in moist conditions, flooding has not been an ideal method to get rid of old world climbing fern. The use of herbicides is the only effective method of control. Studies are ongoing on the biological control of the old world climbing fern. This method is still in its infancy.
Chemical control
This involves the use of chemicals to control or inhibit the growth of the old world climbing fern. The chemicals can also be used to get rid of old world climbing fern. The herbicides are mostly sprayed on the selected plants to eliminate them.
This is because some herbicides are non-selective and they might destroy any plant they come into contact with. This means even the desired plants can be affected by this control method if it is not done effectively. It then calls for caution to be exercised when spraying the chemicals to eliminate the weeds and leave the desired plants so that they can regenerate.
Types of herbicide
Herbicides containing glyphosate, metsulfuron, triclopyr, and imazapic are usually effective in controlling old world climbing fern. The spraying should be done for at least two years and at an interval of six months for effective control. This is because six months after spraying the plant, it grows again from the rhizomes. After 12 months and beyond, the plant grows from spores. Studies show that this method has a success rate of above 96% if it is done effectively.
The herbicides used commonly contain glyphosate and metsulfuron. Triclopyr is not commonly used because it ends up destroying the non-target plant species. This is because it is a non-selective herbicide that will destroy any plant it comes into contact with. Imazapic is rarely used in the control of the weeds because it usually lacks licenses to be used in aquatic areas.
Most landowners use the three herbicides in the control of the weeds. This has however faced opposition because it is believed that the old world climbing fern is developing resistance to the herbicides. Land managers are advised to alternate the use of the three herbicides. This goes a long way in breaking the cycle and therefore making it difficult for the weed to develop resistance to the herbicides.
Herbicide application
Extensive snake fern infestations are usually sprayed using helicopters. Small and scattered infestations are usually spot treated using a backpack sprayer or handheld equipment. Sometimes the fronds extend up to the tree where herbicides cannot be applied. The fronds should be cut and the herbicides are sprayed around the root portion of the old world climbing fern. This method is usually known as poodle cutting. After treatment, the sections should be constantly monitored. This should be at an interval of 6 months and any regrowth spotted should be sprayed.
The herbicides are usually mixed with water. An effective glyphosate solution requires one to put 4lbs per gallon. This is then applied at a rate of 7.5 pints per acre. This should be done when the non-target plants are dormant. On the other hand, the application of a solution that contains 60% of the metsulfuron is usually encouraged.
Once the spraying is done, spot treatment of the old world climbing fern is usually applied after one year or one and a half a year. It can also be mixed with a little concentration of the metsulfuron solution for the best results.
A recent study of the success rates of application of the herbicides yielded positive results in getting rid of old world climbing fern. Herbicides containing glyphosate yielded an 87% reduction of the weed population. The application of herbicides containing metsulfuron yielded a success rate of 99% after the one-year re-spraying.
Biological control
This is the use of living organisms such as insects, nematodes, bacteria, and fungi to get rid of old world climbing fern. These either destroy the plant or inhibits its growth. Most of the agents used usually feed on the target plant at various stages of its lifetime.
A defoliating moth called Austromusotima camptonozale was introduced in South Florida to deal with the populations of the plant. The experiment never made much of an impact and it was abandoned. Another moth called Neomusotima conspurcatalis was introduced in the target area and it proved to be an improvement of the last experiment. The moth has been successful in wiping out the fern’s population in some areas. Even though it is has been proven to wipe out the weed, its impact is considered limited.
Another agent that was released to contain the population of the invasive weed is the leaf galling mite. It is commonly known by its scientific name Floracarus perrepae and was released in 2007 across Florida. Its impact is also not clearly known but there have been reports of the success of the method.
Mechanical control
This involves the use of physical activities to inhibit the growth of a weed. These methods are aimed at causing injury, killing or even making the growing conditions to be unfavorable to the weed. The methods are usually effective if they are accompanied by other methods of control. These methods include;
Weed pulling
The weed can be controlled by this method. It involves the removal and uprooting of old world climbing fern from the soil. It requires one to pull gently because violent pulling will make the plant to break and some parts of the root will remain. This will lead to the regrowth of the plant. Disposal of the uprooted plant is also important. This is because the careless disposal of the plant will only lead to the spread of the plant because of the spores produced. The method is only effective in areas with scattered or small infestations.
Prescribed fires
This method involves the use of fire to destroy predetermined plants under specific desired conditions. The ferns are burned under a controlled environment so as to destroy them. This method is effective in regaining the area’s ecological balance which the fern had destroyed.
This is because it improves the fire resilience of the native plant community and also encourages regeneration of the vegetation. The only downside of this method is that it gives the invasive non-native plant species a chance to thrive. This is because they are likely to regenerate and recolonize the area again with ease.
Photo by Amy Ferriter, State of Idaho, Bugwood.org
Flooding
This involves the saturation of an area’s soil for a period of about two months. The method is effective such that it cuts the oxygen supply to the plant. The method has been found to suppress established old world climbing fern.
Its seeds are also destroyed because the oxygen necessary for their germination will not be available. This means that the seeds will be destroyed and therefore the plant population will be phased out. This method however has is not very effective because the plant thrives under moist conditions.
Bonus: 5 quick facts about the old world climbing fern
- The old world climbing fern has some medicinal value. The plant can be used to reduce urine volumes and prevent inflammation in the body.
- Old world climbing fern is a perennial plant meaning it can survive for more than 2 years. It can also propagate via the distribution of various parts of the plant.
- The plant’s leaves can be used to make ornaments.
- Old world climbing fern produces reproductive and non-reproductive leaves.
- The plant does not have flowers. Instead, it produces spores.
Conclusion
In conclusion, the old world climbing fern is an invasive weed that causes a lot of harm. It raises the cost of maintaining forests and rangelands through herbicides spraying. The numerous research resources used to come up with the control measures are expensive.
It reduces forest cover by acting as a propagator of wildfires. It interferes with the ecological balance of the invaded area. Therefore, it is prudent enough if urgent measures are taken to manage the invasion of the weed. Once the other control methods are fully operational, the control of the weed will be more effective.
References
- University of Florida: Natural Area Weeds: Old World Climbing Fern (Lygodium microphyllum) https://edis.ifas.ufl.edu/ag122
- Everglades Cooperative Invasive Species Management Area: WORKING TO PROTECT THE EVERGLADES FROM INVASIVE SPECIES https://www.evergladescisma.org/the-dirty-dozen/old-world-climbing-fern/
- S. Department of Agriculture: Old World Climbing Fern https://www.invasivespeciesinfo.gov/profile/old-world-climbing-fern
- BioOne Complete: Tolerance of Old World Climbing Fern (Lygodium microphyllum) Spores to Herbicides https://bioone.org/journals/Invasive-Plant-Science-and-Management/volume-4/issue-4/IPSM-D-11-00017.1/Tolerance-of-Old-World-Climbing-Fern-Lygodium-microphyllum-Spores-to/10.1614/IPSM-D-11-00017.1.short
