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Japanese dodder (Cuscuta japonica)
ODA rating: A

Other common names
Giant Asian dodder, Tu Si Zi

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Images courtesy of Kim Camilli, Texas Forest Service, Bugwood.org.

If images are downloaded and used from the ODA web site please be sure to credit the photographer.

Japanese dodder vines are leafless, 1-3 millimeters in diameter with vibrant yellow-green or gold coloration. Purplish spots are also present. The vines contain no chlorophyll. Japanese dodder has thick, spaghetti-like, robust stems in contrast to native dodder stems which are usually more thread or string-like. Infestations are often large, spreading, and web-like, covering large shrubs and small trees. In contrast, infestations of other dodder species are likely to be smaller, infecting non-woody plants or small shrubs. For example, the invasive alfalfa dodder, common in alfalfa fields in Oregon, is bright yellow but far less robust. Flowers, if present are small, pale yellow to cream colored and are found growing on short dense spikes. In cooler climates plants die back in the winter but in warm regions, the species grows almost continually year-round. In California, most Japanese dodder infestations have been found in residential areas and ornamental plantings. A few escaped riparian infestations have also been discovered. Most finds have been located in neighborhoods populated by people of SE Asian decent. This connection is a result of intentional plantings grown as a source of medicinal herbs. Japanese dodder is unlikely to be found in hot, dry desert climates or at high altitudes but it thrives in temperate climates throughout Asia indicating that its potential habitat in North America is large (Markmann and Marushia 1999). Seed production in California and Texas has not been observed(Markmann and Marushia) and therefore not a contributor to localized spread in these states. Other southeastern US populations, on the other hand, can produce some viable seed, increasing the rate of spread that occurs in that region. Seeds disperse by moving water, soil disturbance or on transported machinery. Bird and animal movement may not be a factor. Asexual reproduction also occurs commonly through stem fragmentation and is a highly effective dispersal mechanism, seriously complicating control efforts. Intentional introduction through seed importation and planting also contributes to new introductions in California. Public education and a strong early detection programs have been initiated to limit this activity. Some infestations are the result of dodder seed contamination in agricultural products imported from foreign sources. This source remains a constant threat to high value agricultural commodity production. USDA-APHIS inspection services have intercepted several contaminated products during routine inspections (Markmann and Marushia), though others undoubtedly escape detection.

In several southern states, Japanese dodder is well established in wild lands, nature reserves, roadsides, and on unimproved property. The species sickens and often kills its plant hosts. The loss of these plants in riparian areas would impact food chains, nesting habitat, streamside shading, erosion control, and a host of related benefits. Taller trees are resistant to the serious effects of infection but the impact on understory species could be widespread. Japanese dodder is a serious economic threat to the agricultural and horticultural industries of many states. It is a Federally listed “A” rated species nation-wide and is restricted from all commerce and transport. Should the species become established in the Pacific Northwest and become widespread, the economic impact would be significant to the horticultural industry, to gardeners, orchard owners, park managers and to businesses associated with the production and care of ornamental plants. Potential impacts include: increased inspection of ornamentals grown for export, loss of markets due to the imposition of quarantines, infested private landscapes would have to be removed and replanted, maintenance costs in parks and public landscapes would also increase. Agriculturally, commercial fruit and nut trees would become infested and need to be removed. The species also serves as a host for several citrus viruses and “yellowing viruses” known to be detrimental to agricultural crops.

Japanese dodder is common throughout eastern Asia. Japanese dodder and other dodders seeds are an ancient Chinese herbal remedy for impotence and improving male libido. It is also believed to provide internal balance by nourishing the kidney yin and yang (Chineseherbsdirect.com). It is the leading ingredient for many leading herbal male enhancement products on the market today. It ranges from China, Taiwan, Hong Kong, Manchuria, Japan, Korea, and Russia (Amur and Eastern Siberia). It is hardy in temperate to warm temperate climates (Markmann and Marushia). Significant infestations are found in Florida, South Carolina, and Texas (Markmann and Marushia). In California, Japanese dodder has been located in Shasta, Yuba, Contra Costa, Sacramento, Los Angeles, and seven other counties. The Shasta county infestation, located in Redding, is the most northern infestation identified. It was not controlled but died naturally during the winter. (CDFA weed alert). 

Distribution in Oregon
This plant is not currently known to occur in Oregon.

Biological controls
Biological control agents are not used on "A" listed weeds in Oregon. This weed is being managed for eradication.
Informational links:
Oregon WeedMapper