Cape Ivy (Delairea odorata, an invasive plant originating from South Africa, was introduced to the U.S. as an ornamental vine in the late 1800’s. It subsequently escaped into the wild and has infested coastal areas from California to Oregon.

The plant grows tenaciously in wetlands and streams, smothering native plants and often dominating the riparian understory. Under the right conditions, it may also spread into a forest understory, shrub thickets and grasslands. The vine tends to form a thick carpet and is considered poisonous. Preliminary research has indicated a toxicity to aquatic organisms.

The California populations of cape ivy produce little viable seed. Nonetheless, the plant is still very difficult to control because of its ability to resprout from small fragments. Any fragments left behind after removal can result in a reinfestation. Successfully removing cape ivy generally requires several control treatments.

Notably, the plant is not a dominant understory species in South Africa. This implies that there are control mechanisms that keep the vine in check in its native range. Several insects have already been identified that feed on the ivy, and it is possible that these organisms could be effective biocontrols in the future.

In the San Luis Obispo Coast District, an effort to remove cape ivy has begun in the Chorro Willows area of Morro Bay State Park. The initial treatment consisted of herbicide application by a commerical contractor with three follow-up treatments over several months. New cape ivy populations will be controlled by chemical or mechanical means.

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