Weed Notes: Miscanthus sinensis
TunyaLee Morisawa The Nature Conservancy Wildland Weeds Management and Research http://tncweeds.ucdavis.edu 19 July 1999 Background: Miscanthus sinensis Anderss. is a popular horticultural bunch grass. Many cultivars exist, and have many common names (susuki, fairy grass, eulalia, chinese sedge, japanese silver grass, and maiden grass, etc.). M. sinensis ‘Giganteus’ is primarily grown for the production of bio-energy or paper pulp in Europe and Asia. The quick growing plant also has a use in preventing soil loss in agricultural fields when grown as a hedge. Other Miscanthus species are used for landscaping as well.
M. sinensis prefers full sun and moist, rich soil that drains well. Slight drought can be tolerated once plants are established. New shoots begin to grow from the ground in March or April. Plants tolerate cold climates but do not grow well in hot, humid southern climates. Horticulturists claim it can be grown in zones 5-9, i.e. it can tolerate winter temperatures as low as -26ºC (-15ºF), and can survive as far south as the Florida panhandle. It has been observed escaping along roadsides in North Carolina (Enloe, 1999). Mutoh (1985) observed that M. sinensis populations grew in disturbed areas that had been burned or cut.
Reproduction: M. sinensis has a branched, subterranean rhizome system. It spreads rhizomatously, and pieces of rhizome 4 cm long can be used to propagate the plant (Nielsen, 1987). Research to determine if plants bought from nurseries are self-seeding is occurring currently. Aficionados of bunch grasses feel this plant rarely or never produce seed, although some strains of Miscanthus sinensis seed easily. Replanting with desirable plants after the removal of M. sinensis should occur as Mutoh (1985) observed that Miscanthus invaded soil that had been disturbed by burning or cutting. On the whole, Miscanthus does not seem to pose as aggressive a threat as other invasive grasses.
Mechanical Control: The ability of M. sinensis to reshoot from pieces of rhizome makes control difficult. The whole underground rhizome system must be killed in order to prevent regrowth the next year. Digging out plants will probably result in resprouts and would need follow-up treatments. Similarly, discing and cutting methods may spread rhizome pieces into clean areas.
Burning/Cutting/Grazing: M. sinensis productivity is lessened with defoliation (Huggett, 1997), but the effects of grazing, burning, and cutting in various combinations are not at all consistent. No single approach has yet been shown to be consistently effective, although the amount of Miscanthus present and its seed production can be reduced by using any of them. In Japan, a M. sinensis grassland tolerated being cut 1-5 times over the course of five months (Hayashi, 1994). A study in Korea found that M. sinensis still dominated plots after cutting and was present in uncut burned areas (Che, 1997).
Meanwhile, in agricultural settings, weeding and grazing close to the ground provided control of M. sinensis. Weeding around the crown of planted trees (one-year-old Cryptomeria japonica and Chamaecyparis obtusa) was successful if M. sinensis was cut at a low height (Tange, 1993). M. sinensis grazing in a Japanese conifer plantation provided significant control of weeds (Nogami, 1993).
Chemical Control: As with similar bunchgrasses and Pampas grass, the best control would probably be achieved by using a foliar application in the fall (2% RoundUp or 1% Fusilade) or in the late spring (4% RoundUp or 2% Fusilade) (Enloe, personal communication; Drewitz, personal communication). Lower rates are required in the fall since translocation to the rhizome is occurring at that time. It is unknown how cutting prior to application would affect effectiveness during either season.
References: 1. Che-S., W. Kim and S.H. Che. 1997. Comparison of plant communitystructures in cut and uncut areas at burned area of Mt. Gumo-san. Journal of Korean Forestry Society 86(4):509-520. 2. Drewitz, J. J. 1999, personal communication.
—HUMULUS.DOC— 3. Enloe, S. F. 1999, personal communication. 4. Hayashi, I. 1994. Experimental community ecology in Miscanthus sinensis grassland - change of species composition according to mowing frequency. Japanese Journal of Ecology 44(2):161-170. 5. Huggett, D.A.J. 1997. The effect of timing and severity of artificial defoliations upon the yield of Miscanthus sinensis 'Giganteus'. Aspects of Applied Biology 49:129-136. 6. Kees, H., H. Raab and A. Penzkofer. 1994. Weed management in Chinese sedge (Miscanthus sinensis) - first experiences in Bavaria. Gesunde Pflanzen 46(4):139-143. 7. Kim, Y.J., G.J. Park, S.S. Choi, S.J. Hwang and W.B. Yook. 1995. Ecological studies on weeds in cultivated pasture. II. Effects of pasture management and utilization characteristics of weed development. Journal of Agricultural Science and Livestock 37(2):564-572. 8. Mutoh, N; Kimura, M; Oshima, Y; Iwaki, H. Species diversity and primary in Miscanthus sinensis grasslands: 1. Diversity in relation tostand structure and Botanical Magazine Tokyo, v.98, n.1050, 1985:159-170. 9. Nielsen, P N. Vegetative Propagation of Miscanthus sinensis Cultivar 'Giganteus'. Tidsskrift for Planteavl, v.91, n.4, 1987:361-368. 10. Nishiwaki, A., K. Sugawara and I. Ito. 1996. The effect of cattle grazing on seed production in Miscanthus sinensis Anderss. Grassland Science 42(1):47-51. 11. Nogami, K., Y. Muramoto and M. Nakagawa. 1993. Grazed plants by Wagyu cattle and weeding of Miscanthus sinensis by grazing in young Cryptomeria japonica and Chamaecyparis obtusa plantation. Bulletin of the Faculty of Agriculture, Miyazaki University 40(2):113-119. 12. Tange, T., M. Suzuki, H. Yagi, S. Sasaki and Y. Minamikata. 1993. Influence of the weeding method on the growth of planted trees. Journal of the Japanese Forestry Society 75(5):416-423.
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