Dodder Danger

A new invasive alien plant has appeared in California--a bright-yellow, leafless, parasitic vine called Japanese dodder (Cuscuta japonica), which infests a wide variety of trees and bushes and sucks the life out of them. As of mid-June, this parasite had been sighted at several locations in two counties. It was first found in Yuba County and Redding in early 2005, then at three sites in Contra Costa County.

At an apartment building in San Pablo, the dodder had infested an apple tree, a privet, a rose bush, and other plants. It was removed, along with the infested plants, and buried. At a restoration site on Cerrito Creek on the Albany-El Cerrito border, it was found on willow, plum, and elderberry; on Wildcat Creek in San Pablo, on California live oaks and California buckeyes. Eradication was scheduled within weeks.

The plant spreads both by seed and vegetatively; the long, succulent tendrils break off easily. Once it finds a host, it sends root-like structures called hausatoria into limbs to suck out the tree's water and nutrients. It forms dense tangles and weakens or eventually kills its host.

Japanese dodder is native to Asia, where it is used as an herb, and may legally be imported for such use. Its seeds are used to stimulate the liver and kidneys, as an aphrodisiac, and to treat a variety of ailments including diarrhea and constipation. Imported seeds are supposed to be sterilized, but the California Department of Food and Agriculture (CDFA) has found viable seeds being sold. The U.S. Department of Agriculture has quarantined the dodder, but that may not stop its rapid spread in wildlands, gardens, and orchards. Agency representatives have been visiting ethnic markets and health food stores to collect seeds for testing to make sure viable seeds are no longer for sale.

If you see Japanese dodder, don't try to eradicate it yourself. Instead, inform your local agricultural commissioner or U.C. cooperative extension (in Contra Costa County contact Vince Guise: vguis@ag.cccounty.us). The surest way to get rid of it is to remove the entire host tree or bush down to the ground, double-bag everything, even small fragments, and make sure the bags are deeply buried in landfill. Do not compost!