''Miconia crenata'', (syn. ''Clidemia hirta''), commonly called soapbush, clidemia or Koster's curse, is a
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...
invasive plant species
An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...
in many tropical regions of the world, creating serious damage.
Description
''Miconia crenata'' is a densely branching perennial shrub normally growing 0.5–3 m tall, but sometimes growing 5 m tall, depending on habitat.
The branchlets are covered in large, stiff, brown or reddish-colored hairs. The simple leaves are oppositely arranged, oval-shaped in outline with a broad base, pointed tips, and almost entire to crenate or finely toothed margins. The leaves are also sparsely covered in hairs above, while more densely hairy beneath; and also have five distinct veins that run in an almost parallel fashion from the leaf bases to their tips.
The flowers are arranged in small clusters at the tips of the branches. Each flower has five white, or occasionally pale pinkish, petals and five distinctive stamens that have a claw-like appearance. The base of the flower is swollen into a cup-shaped structure which is moderately to sparsely covered with a mixture of bristly and sticky hairs.
The small, rounded fruit are berries and are either dark blue, purplish or blackish in color. Each of these berries contains over 100 light brown colored seeds.
Distribution and habitat
Native from tropical areas in the
Americas
The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World.
Along with th ...
(
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
to
Paraguay
Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...
as well as the
Caribbean region
The Caribbean region of Colombia or Caribbean coast region is in the north of Colombia and is mainly composed of 8 departments located contiguous to the Caribbean. This species grows in dry to wet tropical climates up to 1200 m of elevation.
Vernacular names
"Koster's curse" is a commonly used name in places where the plant grows as a noxious weed, such as
Hawaii
Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...
. It was introduced to Fiji in the late 1800s, likely by a coffee planter named William Parr who shared his seeds with others across the region; however the introduction was apparently misattributed by locals to a neighboring sugar planter named Köster. Other common names reported for this species are soapbush and clidemia.
As an invasive species
This species is native to much of tropical America, but is an invasive species in Southern Asia, East Africa, and some oceanic islands (like Hawaii and Australia) with warmer climates. It is a potential weed of wetter pastures, open grasslands, plantations, roadsides, wetter open woodlands, riparian zones (banks of watercourses), forest margins and rainforests. ''M. crenata'' can form dense thickets that smother plantations, pastures and native vegetation. Disturbance is a key element in the establishment and invasion of the plant. Wildfires, landslides, windstorms and other forms of soil disturbance (such as pig rooting) accelerate the dominance of this weed (Smith Undated; Peters 2001).
In its native environment plants are confined to open areas and only become dominant about twelve months after disturbance, such as in slash-and-burn agricultural areas (Burkhart Pers. Comm, in Smith Undated). All new range extensions in Hawaii begin along the open edges of trails or other disturbed areas.Global Invasive Species Database. Clidemia hirta (shrub). Web. 2006. In Hawaii, ''M. crenata'' is replacing the endemic species that formerly dominated the forests and threatens their extinction. Elsewhere, it is regarded as one of the most problematic invasive species in the Comoros Archipelago, on La Réunion, in the Seychelles and on Mauritius. 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.
Control strategies/biological control
In order to keep the weed out of an area the primary management objective should be to minimize and prevent disturbance (Smith Undated). Manually pulling plants out of the ground supplemented by herbicide application is an effective but temporary control method. The
thrips
Thrips (order Thysanoptera) are minute (mostly long or less), slender insects with fringed wings and unique asymmetrical mouthparts. Different thrips species feed mostly on plants by puncturing and sucking up the contents, although a few are ...
species ''
Liothrips urichi
The Clidemia thrips, ''Liothrips urichi'', is a thrips species from Trinidad. It is used as a biological control agent to stop the spread of '' Clidemia hirta'' (Koster's curse), an invasive plant species
An invasive species otherwise known ...
'' from
Trinidad
Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...
is being used to biologically control ''M. crenata'' and is very effective in pastures but much less so in woodlands; it was first employed on Fiji in 1930 (Simmonds, 1933). Controlling feral pig populations (''Sus scrofa'') has been widely suggested as an effective means to reduce the spread of ''M. crenata'', as ground disturbance by these exotic mammals is strongly linked to the successful establishment of ''M. crenata'', as well as a number of other invasive plants such as ''Morella faya''.
Although sheep have been shown to control most weeds in plantations, they will not eat ''M. crenata'' (Francis, 2004).CABI. “Koster’s Curse.” Datasheet. https://www.cabi.org/isc/datasheet/13934. According to Mune and Parham (1967), no effective chemical control for ''M. crenata'' exists. However, Teoh et al. (1982) report that ''M. crenata'' may be killed by applications of triclopyr. Norman and Trujillo (1995) have found that a
mycoherbicide A mycoherbicide is a herbicide based on a fungus. As a biological agent, these "mycoherbicides... work by producing toxic compounds that dissolve the cell walls of targeted plants". Unlike traditional herbicides, mycoherbicides can reproduce themse ...
containing ''Colletotrichum gloeosporioides'' f.sp. ''clidemiae'' as the active ingredient was effective against ''M. crenata''.
Policy and law
''M. crenata'' has been nominated as among 100 of the "World's Worst" invaders by the IUCN Invasive Species Specialist Group and it has been listed as a noxious weed in Queensland and the Northern Territories (Australia) and Hawaii. It is not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.
Occurrence in Australia
An infestation of ''M. crenata'' was found in Julatten (near
Mount Molloy, Queensland
Mount Molloy is a rural town and locality in the Shire of Mareeba, Queensland, Australia. In the the locality of Mount Molloy had a population of 254 people.
It is a historic mining and timber town, north of Cairns in Queensland, Australia.
...
) in 2001. This outbreak threatens to spread into the
Mount Lewis National Park
Mount Lewis National Park is national park in both the Shire of Mareeba and Douglas Shire of Far North Queensland, Australia. It is adjacent to both Daintree National Park and Mount Spurgeon National Park. It is part of the Wet Tropics of Queens ...
and
Mowbray National Park
Mowbray is a national park in Queensland, Australia, 1441 km northwest of Brisbane. The park forms part of the Wooroonooran Important Bird Area, identified as such by BirdLife International because it supports populations of a range of bi ...
. Community-based efforts to control the plant in Julatten are coordinated by the Mitchell River watershed management group.
In New South Wales Australia, there is a hotline number for citizens to call and report to the Department of Primary Industries any noticed occurrences of the plant.