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COA to tackle foreign weed species

Different kinds of dodders are now common in not only coastal sites but also urban areas in Taiwan. A dodder is a leafless parasitical vine with yellowish threadlike stems. It attaches itself to other plants and takes nourishment from the host plant. PHOTO COURTESY OF THE COUNCIL OF AGRICULTURE

To guard against the threat of a possible spread of the parasitic weed known as dodder, the Council of Agriculture (COA) yesterday said it plans to discuss the matter.

The move was a response to two ecologists, who urged council to investigate the potential danger posed by the spread of Japanese dodder (Cuscuta japonica Choisy) in central Taiwan.

Chen Yueh-fong (陳玉峰) and Yang Kuoh-cheng (楊國禎) of Providence University reportedly said that in several sites local vegetation had been taken over by Japanese dodder, an introduced plant.

In particular, in Wufeng township, Taichung County, the plant can be found spread along a 1km stretch of road where it has squeezed out local plants, they said.

Chen and Yang urged the council to take action immediately, noting that the plant is almost ready to blossom.

Other weed specialists, however, said that the plants found were local. Scientists at the Taiwan Agricultural Chemicals and Toxic Substances Research Institute under the COA said yesterday that the plant identified as Japanese dodder, was actually considered a local plant. To further confirm the species at the sites mentioned by the two ecologists, institute researchers took samples from the sites.

"So far, in Taiwan, researchers have identified golden dodder (Cuscuta campestris) as the only exotic species of dodder," Chiang Mou-yen (蔣慕琰), a weed specialist at the institute, told the Taipei Times.

Because of recent public concern triggered by the discovery of introduced fire ants in many counties, the bureau plans to hold meetings on the management of introduced species. Officials said that Japanese dodder would be discussed, in order to prevent a possible biological invasion.

According to Chiang, dodder is a leafless parasitical vine with yellowish threadlike stems. It attaches itself to another plant and is nourished by that plant. Introduced golden dodder seems to be more aggressive then other kinds.

"We've successfully developed a host-specific fungus, which will kill the golden dodder rather the plant that supports it," Chiang said.

Chiang said that this biologically safe method might be used more widely if the spread of dodder is identified as a threat to crops.

Japanese dodder is commonly found in Japan, Korea, Russia, Vietnam, China and Taiwan, officials of the council's Bureau of Animal and Plant Health Inspection and Quarantine said yesterday. In Taiwan, dodder is valued by followers of Chinese medicine, who say drinking tea made with the plant has certain curative effects.

"In a way, human activities assist the spread of all kinds of dodder," Chiang said.

Since the 1970s, the US has listed Japanese dodder as one of the most noxious introduced weeds. The Asian plant is now found in Texas, Florida and South Carolina.

Officials said that so far Japanese dodder has had a greater negative impact on the ecology in the US than in Taiwan.

In Taiwan, various types of dodder are now commonly found in both coastal and urban areas. Bureau officials said that golden dodder deserves more attention than Japanese dodder, as it has been found on 165 different plants since being introduced to Taiwan in the 1960s.

The resulting ugly landscape caused by the spread of dodder has worried many local governments because plants in some parks and traffic islands have become covered in the silky yellow layers of the plant.
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