Description:
Chinaberry tree (Melia azedarach)
M. azedarach is described as a small to medium-sized shrub or tree in the mahogany family (Meliaceae). Branches are stout, with purplish bark dotted with buff-coloured lenticels. Leaves are twice to three-times compound, alternate, and puberulent to glabrous. Leaflets are 2-8cm long, serrate or crenate, dark green above, often with sparse hairs along the veins, and lighter green and generally smooth below. The inflorescence is a panicle from leaf axils and from leafless nodes on the lower part of the new growth. The perfect flowers are 5-parted. Sepals are green, 1.5-2mm long. Petals are pinkish lavender, ligulate, 1-1.3cm long. Stamens are united into a cylindrical, dark purple tube, 6-8mm long, and cut at the apex into 15-25 slender teeth. Each flower has ten anthers. Flowers are fragrant. The fruit is a stalked, one-seeded drupe that is greenish yellow to yellowish tan, globose, and 1-1.5cm in diameter.
Occurs in:
Natural forests, range/grasslands, riparian zones, ruderal/disturbed, urban areas, wetlands.
Habitat description:
M. azedarach invades along road rights of way, fencerows, and other disturbed areas. It has also been found in upland grasslands, woodlands, and riparian areas in the southeastern U.S. and in southwestern Africa. It grows between sea level and 700m in open dry habitats. It favours old fields, abandoned lots, roadsides, and other disturbed areas. M. Azedarach has begun to invade relatively undisturbed floodplain hammocks, marshes, and upland woods in Florida. In Texas, riparian woodlands and upland grasslands have also been extensively invaded. In Hawai‘i, it is naturalized in dry, disturbed areas, especially gulches and pastures to 610m elevation. In Fiji, it is cultivated or sparingly naturalized at low elevations. States that based on general descriptions of habitat, it is likely that M. Azedarach requires open sun, is not shade tolerant, and is adapted to a wide range of soil moisture conditions. It is highly tolerant of heat and drought.
General impacts:
M. azedarach can invade disturbed and relatively undisturbed areas, and by doing so, it can decrease native biodiversity. It has numerous
Chinaberry tree (Melia azedarach) Distribution in North America shown in green.
defenses against insects and other plant pathogens, giving it a competitive advantage over many native species. Its leaf litter can increase the pH of soils and add nitrogen, significantly altering soil chemistry. Leaf litter of M. azedarach was also effective in reducing aluminum levels in soil. Decaying leaf litter can enhance the soil concentration of mineralizable nitrogen by an amount comparable to nitrogen-fixing legumes. This invasive plant can also successfully reproduce vegetatively, forming dense thickets. These characteristics have contributed to its establishment throughout much of the southeastern United States, where it negatively affects native populations of plants and animals.
Geographical range:
Native range: M. azedarach is native to Southeast Asia and northern Australia.
Known introduced range: It was introduced to the New World and cultivated as a shade or reforestation tree and has spread throughout tropical America, from the southeastern U.S., through some western states, and Mexico to Argentina. It has spread to some Caribbean islands, including Puerto Rico, and is also present in South Africa.
Management information:
Preventative measures: A Risk Assessment of Melia azedarach for Hawai‘i and other Pacific islands was prepared with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived for use in Pacific islands. The result is a score of 14 and a recommendation of: “Likely to cause significant ecological or economic harm in Hawai‘i and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawai‘i and/or other parts of the world.”
If M. azedarach is controlled during the early stages of establishment, the potential for successful management is high. The potential for
Close up of Chinaberry tree (Melia azedarach)
large-scale restoration of wildlands where it has already become established, however, is probably lower due to requirements for longer-term efforts. The best control of M. azedarach, as reported by land stewards/managers, occurs with the appropriate use of chemical methods.
Chemical: In an article describing herbicide control measures for many of the invasive exotic species in Florida,Herbicides and equipment, for the chemical control of M. azedarach. For basal bark treatments (which can be applied to a range of stem sizes, from saplings to large trees) the use of 10% Garlon 4 is recommended. A back-pack sprayer, spray gun or a hand-held spray bottle can be used for application. For cut-surface treatment (which could be tree-injection, girdle (frill) method or a cut stump treatment) the use of 50% Garlon 3A is recommended. Back-pack sprayers or pump-up sprayers are suitable for cut-surface treatments. For foliar spray 1% (high volume) Garlon 3A is recommended. The authors report that the effectivness of the basal bark and cut-surface treatments are ‘excellent’ and that of the foliar spray is ‘good’.
Mechanical: The study into the clonal strategies of M. azedarach state that injury to the plant, by animal-mediated injury at a local scale or by fire on a large scale induced prolific resprouting - thus increasing the density and spread of the species. The authors demonstrate that excised roots initiate the development of adventitious buds and suckers.
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