A Pest You Never Want To See

Sudden oak death (SOD), the plant disease caused by Phytophthora ramorum fungus, was originally discovered in California, where it has killed a large number of oak trees. It’s called sudden oak death because it appears to kill an oak tree in just a few weeks. In 2001 SOD was discovered in a southwest Oregon forest. Last year it was found in British Columbia, Oregon, and Washington on camellias and rhododendrons in nurseries. The infected nursery plants were destroyed, but SOD requires vigilance by horticulturists and home gardeners alike.

Susceptible plants. Oregon myrtle and rhododendron are carriers. SOD is known to affect more than 60 species, including Douglas fir, oaks (except white oaks), witch hazel, and yew.

Transmission. The fungus is spread by windblown rain and carried by infected nursery stock.

Symptoms. Leaf spotting on many plants (such as camellias), rapid twig and branch dieback (on madrones and others), or girdling cankers that quickly kill the tree (on oaks and tanbark oak). It’s always wise to avoid buying any plant with unhealthy-looking leaves.

Treatment. Prune out and burn branches associated with leaf spotting or twig dieback. While there is no viable chemical control, SOD is being studied.

INFO: Visit www.suddenoakdeath.org or call 888/703-4457, or call your county cooperative extension office.