Sudden oak death jumps quarantine

The funguslike microbe that has swiftly killed coast live oaks and other trees in northern California and Oregon has bypassed containment measures and turned up in nurseries to the south, officials announced earlier this month.

During a survey of commercial nurseries, California state pathologists found the sudden oak death pathogen, Phytophthora ramorum, first on camellias at a Monrovia Nursery site east of Los Angeles and then on camellias at Specialty Plants nursery in San Diego County. Samples from other nurseries are also being tested. Pathologists called the Southern California sightings of the pathogen “unexpected” because the dry climate there seemed unfriendly to a funguslike pest.

The announcement raised alarms across the country because California nurseries ship plants nationwide. The states of Georgia and Florida, for example, banned nursery-plant imports from California.

U.S. pathologists first noticed the disease in 1995, when some trees on the north Pacific coast developed oozing sores and died. In 2000, researchers identified a previously unnamed Phytophthora, a relative of the microbe that caused the potato blight in Ireland in the mid-19th century (SN: 8/5/00, p. 68: Available to subscribers at Team corners culprit in sudden oak death). P. ramorum attacks a wide range of species, killing some but doing nothing worse than causing leaf spots in others. Tests have shown that some East Coast species, including some oaks, could catch the disease.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.

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