Scientific name: mikaniamicrantha English name: southamericanclimber, mile-a-minute weed Category: genus Asteraceae (compositae), false Eupatorium genus (mikenia) perennial herb Has now been included in the first batch of alien invasive species in China. Description: Perennial herbaceous or slightly woody vines. The stems slender, creeping or climbing, multi-branching; stem leaves triangular-shaped oval central; flowers white, tubular, bell-shaped canopies Department, aroma, five cracked teeth; capitulum majority of branches often arranged in complex corymb shape, peduncle slender. Mikania species of both sexual and asexual reproduction on both sides. In the autumn and winter when the temperature is below 20 ℃ for sexual reproduction will be in winter, not many flowering plants, Mikania micrantha in this season, has become an important honey plant. The very small seed material, achenes black, pappus white, 0.1 mg per seed, however, the wind drift can be migrated to distant land. Wind spread the seeds are spread widely Mikania important reason for the invasion. Mikania micrantha internode and node can take root, leaf axils of each section of a pair of new shoots can grow to form a new branch line, it is also known as the English name of Mikania "one minute mile." This metaphor of its rapid growth and proliferation. In loose soil, rich in organic matter, the generation of sunny environment, Mikania particularly easy to grow. Mikania common in woodland edges damaged, deserted farmland, lax management of the orchard, reservoirs and canals or river sides. Mikania the source of origin in Central America, where as many as 160 kinds of insects and fungi as natural enemies to control its growth, is difficult to create hazards. Mikania micrantha invasion, because of constraints caused no harmful effects of natural enemies. Mikania micrantha is native to Central America, now widespread in tropical regions of Asia such as India, Malaysia, Thailand, Indonesia, Nepal, the Philippines, and Papua New Guinea, Solomon Islands, Indian Ocean Christmas Island, and Pacific islands including Fiji, Western Samoa, Australia, North Queensland region become the world's tropical and subtropical regions against one of the most serious weeds. About as a weed Mikania micrantha in 1919 appeared in Hong Kong, China, discovered in 1984 in Shenzhen, now widely distributed in the Pearl River Delta region. The species has been included in the 100 world's worst invasive alien species. Mikania micrantha is a hi-positive plants, hi, light and water conditions, growing in areas with better, the average annual temperature above 21 ℃, the requirements of the soil environment in a very low reproductive capacity with the likes of super-climbing vine, After climbing on shrubs and trees, cover the whole plant can quickly form a trend, and can secrete venom, inhibit the growth of other plants. Full coverage of other plants, the result of damage to leaving the plant photosynthesis suffocation. Mikania for 6 to 8 meters of natural secondary forest and artificial fast-growing forest, forest, forest landscapes are a serious threat to almost all species, the use of climbing all the coverage limit the secretion of venom inhibition of photosynthesis and growth of other plants to kill another important means of The parasitic trees, resulting into the woods and die. The typical invasion of Mikania micrantha invasion is the Lingdingyang in the Pearl River estuary Lingding Island, 460 hectares to the island nature reserve 80% of forest damage by Mikania micrantha, an area of serious catastrophic harm up to 80 hectares. The nature reserve where more than 600 monkeys live and pangolins, pythons and other protected animals, these monkeys live on bananas, litchi, longan, orange, and some wild shrubs and trees are covered by Mikania large, difficult to carry out normal photosynthesis their ecological environment has been devastating, threatening the island mangroves, hamadryad monkeys and birds to survive. Turn of the century, Guangdong Province, Shenzhen and Zhuhai has organized a manual removal of Mikania, but with little success, Mikania often come undone loss. Now trying to carry out chemical control and the search for natural enemies of Mikania micrantha to comprehensive treatment. Rampant in the woods in the introduction of Mikania parasitic dodder field, it's tender parasitic Mikania technology, young leaves, young stems above, draw micrantha for its own growth and nutrition. The end result is a small amount of Mikania micrantha the woods there, a few of the Dodder exists, but the forest does not constitute a hazard. Shenzhen researchers after 5 years of scientific research, and found an effective way to inhibit the proliferation of Mikania micrantha. Mikania micrantha is harmful to our country into the most serious against the grass outside one. Experts estimate that China's Pearl River Delta area each year due to flooding caused by Mikania ecological and economic losses of about 5-8 billion. In recent years, Mikania Neilingding Island in Shenzhen, mangroves protected areas spread. Because of the biological properties of Mikania micrantha is not very understanding, after manual removal of Mikania micrantha has been growth, there is no good way to eradicate them, such as Shenzhen Neilingding Island covered large areas of forests have been Mikania, resulting in dead trees, habitat for the monkeys in the woods thus threatened. Now researchers with field dodder inhibition Mikania, micrantha Neilingding the number of the island has been greatly reduced. Local plant experts in the Pearl River Delta has accidentally discovered during the census, the local native species Pholiota adiposa Maple can also inhibit the proliferation of Mikania micrantha. Pholiota adiposa Feng to secrete a chemical to inhibit the growth of Mikania micrantha. Lingding island, including through the cultivation of two plants, and with specific pesticide use, Mikania micrantha hazard area has increased from 5.54 square kilometers down to the present 3.3 square kilometers.
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Morphology
Mikania (Figure 2) Mikania micrantha is a perennial herbaceous or woody vines, stems slender, creeping or climbing, multi-branched, pubescent or glabrescent, childhood green, nearly cylindrical, the old stems light brown, with a number of rib. Middle stem leaves triangular-shaped oval to ovate, 4.0 ~ 13.0 cm, width of 2.0 ~ 9.0 cm, base cordate, even near halberd-shaped, apex acuminate, rough edges with a few jagged teeth or shallow wavy circle, two non- Mao, the base from 3 to 7 veins; petiole length of 2.0 ~ 8.0 cm; the upper leaves gradually smaller, have short petioles, flower heads most of the side branches often arranged in complex corymb shape, inflorescence gradually thin, the top Capitulum flowers open first, followed by down gradually opening up, capitulum length of 4.5 ~ 6.0 mm, with flowers four, all for the strong gender flower bracts 4, narrow elliptic, apex acuminate, some urgent sharp, green, long 2 ~ 4.5mm, total bud oval base has a small linear bracts (outer bract), length 1 ~ 2mm, flower fragrance; Corolla white, ridged, long 3 3.5 (- 4) mm, the Ministry of bell-shaped canopies, 5 teeth crack, achene length of 1.5 ~ 2.0mm, black, coat, with 5 edges, are glands, crested 32 ~ 38 (-40) of bristle composition, white, length of 2 ~ 3.5 (-4) mm.
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Geographic distribution
Mikania (Figure 3) located in India, Bangladesh, Sri Lanka, Thailand, the Philippines, Malaysia, Indonesia, Papua New Guinea and the Pacific islands, Mauritius, Australia, Central and South American countries, the southern United States. Guangdong, Hong Kong and Macau.
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Biological properties
Slow initial growth of M. micrantha seedlings, seedling height at 1 month was only 11cm, leaf area 0.33cm ². But with the growth of seedling age, growth is facilitated, the internode easily the roots, stretching from the soil absorb nutrients, so the nutrients can be strong stems vegetative propagation, but also much faster than the growth of seedlings, Mikania the growth of a section one day almost 20cm. Including Lingding Island, a section of Mikania micrantha branching out in a year in the growth of all sections of the total length of 1007m. Because of its spreading fast, so that some scholars called for the "one minute mile weeds." Fruit period: in Canton next year from August to February. In the laboratory under controlled conditions, Mikania seeds in the 25 ~ 30 ℃ 83.3% germination rate, germination rate at 15 ℃ was 42.3% lower than 5 ℃, 40 ℃ higher than that under the conditions of poor germination. Light conditions conducive to seed germination, dark and difficult to germinate. Seeds before germination may have a 10d or so "after-ripening period." After the seeds mature natural storage 10 ~ 60d, germination rate was higher the longer the storage time, germination rate is lower.
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Hazards
Mikania (Figure 5) Mikania micrantha is a perennial vine, wrapped in its proper habitat, climbing trees and shrubs at the plant, the weight of its canopy top, with the main impeding photosynthesis and then attached to the main cause of death, is the world's most dangerous and harmful plants. In China, the main hazards Mikania natural secondary forest, plantations, mainly on the local 6 ~ 8m almost all of the following species, in particular, a number of small forest canopy density against the most serious. Serious harm has mangrove tree species, Macaranga, crape myrtle, mountain Vitex, Ficus; serious harm has lantana shrub species, acid vine fruit, white acid vine fruit, plum Ilex, Rhus, under the leaves beads, red back Guangxi, etc.; against heavier tree species have longan, sapodilla, juniper, neem, guava, hackberry, litchi, paniculata, iron holly, sassafras, camphor tree, tallow; against heavy shrubs There myrtle, citrus seasons, Huashan alum, to peach, flower buds and other dogs. Neilingding Island in Guangdong, Guangxi Development typical white wood - thorn Kwai - Oil vertebral evergreen broadleaf forest community, almost covered by Mikania micrantha, in addition to the big white high Katsuragi, the thorn bushes have all been covered by the following Kwai, growth was seriously affected communities in the shrub and herb species composition was significantly reduced. Woodland trees, forest trees are Mikania wound edge, there shoot blight, stem blight phenomenon, showed obvious retrograde succession.
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Control Measures
Mikania (Fig. 6) the use of herbicides, "Cao Ba Wang" (Bentazon) and "picloram" (TORDON) treatment Mikania seeds, chemical and concentration of 0.4% of the "Cao Ba Wang", 0.2% of the "picloram." With 70% ethyl (Sulfometuron Methyl), Sulfometuron trade name, dosage was 0.1g / m², 2,500 times diluted with water spraying. Sulfometuron application should avoid the attention of other sensitive plants (eg Ficus, wild hemp storage, such as trees and shrubs Lantana and other Compositae, Cruciferae, Gramineae) in order to free from injury. Damage by controlling the plant field dodder, field dodder parasitic and death micrantha can make the coverage of Mikania from 75% to 95% to 18% ~ 25%, better controlling the plant's hazards, and will not have other plants within the plots as an important fruit trees, food crops, vegetables and other damage to landscape plants. Purple mite short to be used for controlling the plant, through vaccination purple wax eggs to be short, after 3 months, can Mikania vine leaves into a piece of yellow curls, 6 months later, Mikania leaf yellowing, edges do not neat, horizontal narrow, over time, gradually withered Mikania micrantha. Aphis citricola Quedui Mikania also has good control effect.