Restoration Potential: Recovery potential of plant communities from which clidemia has been removed has not been examined. Recent mortality to clidemia in drier sites with a biological control pathogen (Colletotrichum gloeosporoides) may test the potential of native forest recovery. Smith (in press) is concerned about the spread of strawberry guava (Psidium cattleianum) or alien grasses into gaps created by loss of clidemia to biocontrol agents. Alien plants often are successful invaders of such open habitats.
Management Requirements: Smith (in press) is skeptical of the efficacy of manual, mechanical, and chemical means of control (Smith in press). Although many clidemia plants can be manually uprooted, efforts to control small populations have almost always failed. In addition, seedling recruitment is prolific, small plants grow rapidly, and seed banks are large and persistent. Finally, similar to other Melastomes, uprooted clidemia may resprout when uprooted in wet areas. However, long-distance establishments can probably be controlled if effective herbicides are identified. These can be used on slash of manually removed plants, for foliar treatments of larger populations, and on dense mats of seedlings.
However, controlling small populations that represent new long distance establishments in otherwise clidemia-free sites makes sense. This is the strategy being employed at Kamakou Preserve. Biocontrol is often only partly successful, and the recovery of native plant communities following removal of clidemia is problematic (Markin in press, Smith in press). Long-distance establishment sites are in disturbed areas such as trails or roads. Such sites lend themselves to early discovery, and are important because they readily serve as the seed source for further dispersal vectored by humans.
Manual control works for all but the largest plants or those in rocky soil. Mechanical aid such as picks are needed for some plants (Harada pers. comm.).
Effective herbicidal control has apparently not been applied in Hawaii, although control methods have been developed in Southeast Asia (Heong et al. 1982).
Use of Colletotrichum in drier sites is warranted. This herbicide is now permitted on an experimental basis (Tanimoto pers. comm.). Probably the best strategy for areas with little or no clidemia is to vigilantly monitor predictable corridors of invasion and eliminate populations, preferably before seed is set, innoculate nearby populations with available biocontrol agents, and support biocontrol efforts in the state. Retreatments are required at less than six month intervals to prevent seed production.
Management Programs: Volunteer groups have attempted to control infestations in Wailau and Waimanu Valleys with little success (Smith in press). Kamakou Preserve has been successful in preventing the spread of its one known infestation. Other efforts Oahu and elsewhere have generally failed (Smith in press).
Monitoring Programs: Monitoring is now being conducted to assess the effectiveness of introduced biological control agents, particularly to assess the density, extent, and presence of all life stages. This is described below under research programs.
Management Research Programs: No studies on ecology and life-history are known to be in progress. Wester and Wood (1977) and Smith (in press) have summarized observations about phenology, distribution, and ecology of clidemia.
Considerable research to identify potential biological control agents has been conducted, several releases have been made (Nakahara et al. in press), and monitoring of releases is now in progress. The thrips Liothrips urichi was released in 1953. This agent has been judged to be effective in open areas such as pastures and cultivated lands, but has had little effect in shaded sites. The search for biocontrol agents for forested sites lead to the mostly unsuccessful release of three moths during the 1970's. Intensified exploration in the natural range began in 1982. Fourteen insects were identified as potential biological control agents to attack leaves, flowers, and stems. One of these, Lius peisodon, a beetle, has been recently released and is being monitored on Hawaii Island and Oahu (Campbell pers. comm.). Lius has had little overall impact to date, but appears to attack plants in the shade, in contrast to Liothrips.
A fungus Colletotrichum gloeosporiodes was introduced in 1986 (TenBruggencate 1986). This is being evaluated in a number of locations in the state (Tanimoto, pers. comm.). It appears to be successfully controlling clidemia in drier sites, in both shaded and open habitats, but has had little effect in wetter areas. However, Tanimoto (pers. comm.) has not given up on Collectotrichum in wet areas, because the pathogen is very slow acting. Colletotrichum was originally perceived as a microherbicide which needed to be sprayed on target plants because of poor dispersal capacity. It apparently spreads adequately from plant to plant (Tanimoto pers. comm.). A release of the fungus has been made in Pelekunu Valley, and Preserve staff are contributing to its monitoring (Misaki, pers. comm.).
Local herbicide testing suggest little sensitivity to herbicides, although other studies indicate the potential for herbicidal control. Local investigations showed little sensitivity to 2,4-D, dicamba, glyphosate, and triclopyr (Motooka 1987) using the Uyeda drizzle application method (high concentration application to limited area of foliage). Motooka (pers. comm.) characterized it as a relatively herbicide-resistent plant. However, researchers in rubber plantations in Southeast Asia found that 2,4-D amine and triclopyr at 0.7 kg/ha were very effective in control of clidemia (Heong et al. 1982). Differences may be due to application techniques. These studies are a starting point for local research in finding an effective herbicide to supplement manual and biological control methods.
Management Research Needs: If necessary, further studies should be conducted to assess the suitability and effectiveness of additional insect biocontrol candidates. These potential agents have beeen identified for testing and could augment the pathogen, Colletotrichum gloeosporiodes (Nakahara et al. in press, Smith pers. comm.). These studies have been placed on hold until the results of releases of Colletotrichum gloeosporiodes have been evaluated (Markin pers. comm., Smith pers. comm.). Smith (pers. comm.) feels that additional agents may be needed for wet areas, where the pathogen has not been especially effective to date.
Although biological control is the long-term solution to clidemia management, there is a limited role for herbicides. Biocontrol is usually only partially effective and may not prevent the dispersal and range expansion of the species, even though it may reduce the density of infestations when effective. Control of newly established, disjunct populations, which result from long-distance dispersal, is needed to prevent new major infestations and range expansions. Herbicides may be needed to control these outliers, especially if they are too large for manual control. Herbicides are also helpful in wet areas in controlling clidemia slash or uprooted plants which tend to resprout. Finally, herbicides are needed in the control of large populations (several acres) if the native biotic resources at rish are very important. A selective foliar herbicide would be needed for clidemia plants and slash in a chemical control program.
Biological Research Needs: More detailed life history and demographic information may aid in statewide control efforts. Most current information about growth rates, seed viability, and dispersal is largely anecdotal. No such research is needed in the preserves, but is suitable for University researchers to be carried out in a diversity of sites in the state.
Global Range: Clidemia is native to tropical America, including parts of South and Central America and the Caribbean islands (Wagner et al., 1990, Smith in press). Where it has been observed in its native range in Trinidad, it occurs at low density in early successional plant communities (Nakahara et al. in press). Wester and Wood (1977) describe it as a uncommon constituent of secondary rain forest. It is now a pest in much of the Paleoptrics (Wagner et al. 1990), including Oceania, Southeast Asia, and the Indian subcontinent (Smith in press).
It was originally reported from Oahu in 1941, and was considered a noxious plant by 1957 (Smith in press). By 1988 it had expanded into all suitable habitat, with a range over 100,000 ha. Although its distribution has not been systematically studied, small, multiple infestations were reported from all major islands except Kahoolawe and Niihau in the 1970's and 1980's. These reports suggest continued expansion of clidemia on neighboring islands.
Stem: The French Guiana Palikur use leafy branches in a decoction drunk by women having too copious menses. Leaf: In a decoction to cicatrize old wounds; infusion is antidysenteric and antispasmodic; macerated in cold water for a woman's antiseptic genital bath to remedy haemorrhaging. Infusion used to treat stomachache and as an enema in French Guiana.
Stewardship Overview: Clidemia, which forms monospecific subcanopy stands in native forests, is one of the most disruptive alien plants in Hawaii. It is very widespread on Oahu where it spread very rapidly, and has recently become established on almost all the other major islands. Its potential range is very great, essentially all wet and mesic habitats below 1,500 m. Clidemia's success as a weed is due to high production of seed, prolific establishment from seed, rapid growth and maturation, broad environmental tolerances, and availability of dispersal vectors. It is a threat to Kamakou Preserve and potentially a threat to lower elevations in Waikamoi Preserve. Biological control is the long-term solution, and two partly successful biocontrol agents have been released. More are probably needed. Control of long-distance establishments is worthwhile, even though the effectiveness of control efforts has been limited. Research is needed on an effective herbicide to augment manual techniques in controlling new invasions and long- distance establishments.
"Shrubs 0.5-3 m tall; young branches rounded, hirsute. Leaves opposite, 5-16 x 3-8 cm, ovate to oblong-ovate, apex acute to short-acuminate, base rounded to subcordate, subentire to crenulate-denticulate, 5-nerved, upper surface sparsely strigose, lower surface finely bristly, margins ciliate; petioles 0.5-3 cm long. Pedicels 0.5-1 mm long in fruit; hypanthium 3-3.5 mm long, moderately to sparsely finely bristly, usually with a mixture of gland-tipped and stellulate hairs; receptacle bearing a conspicuous ring of fimbriate scales surrounding style. Calyx lobes broadly ovate to truncate in fruit, ca. 0.5 mm long, the linear external teeth projecting 2-4 mm. Petals white, 8-11 mm long, 4-5 mm wide, glabrous. Staminal filaments ca. 2.5 mm long; anthers 3.5-4.5 mm long, dorsal spur at base ca. 0.25 mm long. Berries 6-9 mm long; seeds 0.5-0.75 mm long."
It was introduced to Hawaiʻi in the 1940s; by 1978 it had spread to over 90,000 acres (360 km2) of land on Oʻahu. In 1972 Koster's Curse was first spotted on the Big Island. In Sri Lanka it is quite invasive in wet zone and upcountry forests, especially invading gaps in the forest, preventing other native species from emerging.
The plant grows 1–5 metres (3 ft 3 in–16 ft 5 in) tall, depending on habitat.
The black berries are up to 8 millimetres (0.31 in) long and taste a bit like a deeply flavored blueberry. Each fruit contains more than 100 tiny (0.5 mm) seeds. It flowers and fruits all year, if conditions are moist enough. A large plant can produce more than 500 fruits in a single year. The seeds are dispersed by birds, feral pigs, other animals, and humans. Sheep will not eat the plant, and the tannin inside the fruits is poisonous to goats. The seeds can remain viable in the soil for up to 4 years.
The human edibility factor of this berry has not been fully explored. The tannin inside of the fruit is not harmful to humans and a delicious syrup may be made from the fruit. The syrup has a beautiful indigo blue color and may be used to enhance and remove the bitterness of teas such as yerba mate.
The epithetonhirta means "scrubby" in Latin. "Koster's curse" is a commonly used name in places where the plant grows as a noxious weed, such as Hawai'i. Koster was the man who between 1880 and 1886 accidentally introduced seeds of C. hirta to Fiji in coffeenursery stock, where its problematic nature was first noticed around 1920 (Paine, 1934; Simmonds, 1937). Originally only known as "the curse" for the damage it did to coconut plantations, its vernacular name became a model after which those of other invasive plants were patterned, such as Ellington's Curse on Fiji, McConnel's curse in Australia, Curse of India in East Africa or Burbank's Folly in the Pacific Northwest.
Koster's curse can form dense thickets that smother plantations, pastures and native vegetation.
Manually pulling plants out of the ground supplemented by herbicide application is an effective but temporary control method. The thrips species Liothrips urichi from Trinidad is being used to biologically control C. hirta; it was first employed on Fiji in 1930 (Simmonds, 1933).
Introducing the plant to Australia can be fined with up to 60,000 (Australian) $.