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Nationwide Alert: Sudden Oak Death
A relatively new and deadly pathogen has become established in certain areas of the United States. First detected in California, this pathogen is a deadly invader of trees of the oak species as well as rhododendron, azalea and camellia. Phytophthora ramorum host species may also include Acer (maple), Aesculus (buckeye), (Hamamelis) witch hazel, (Rhamnus) buckthorn, Sequoia, Trientalis, (Vaccinium) blue berry, (Viburnum) viburnum, (Rubus) blackberry,(Syringa) lilac, (Kalmia) mountain laurel, and (Fagus)beech among others. More Info
The Sudden Oak Death (SOD) spreading pest phenomenon was first detected and identified in the central coastal area of California. As time progressed and the tree cankers spread through thousands of tanoaks, live oaks, and black oak, the newly identified fungus was identified and began to infect more and more susceptible botanicals. In 2002, the disease was known to occur only in California and in some southern areas of Oregon, but infected host plants from plant nurseries were transported from locations in western United States over time to states on the East Coast, spreading the disease.
Oak trees are particularly susceptible to this bleeding canker fungus. On host plants the symptoms of leaf spot and twig dieback are evident. Although host plants may not die from the disease, the fungus may transfer from these host plants to oaks and spread throughout oak trees in adjacent areas. Some testing has shown that the most susceptible species of oaks includes the pin oak and the northern red oak, both valuable forestry tree species and both prevalent in Charles County, Maryland, forests.
Infected trees display a black or reddish oozing from cankers that stain bark surfaces and lichens that are growing on it. Trees with cankers may live a few years, but by the time the crown canopy begins to die off, leaves turn from green to yellow to brown and drop off. Oozing sap bleed from oaks may be difficult to diagnose as it dries or is washed from tree trunks by rain (although staining may remain). Under the bark, black lines may indicate the infection but inspection is insufficient to determine Sudden Oak Death since other pathogens may be responsible and testing of tissue is recommended if SOD is suspected. If unusual oak deaths occur in an area, it is recommended to have trees evaluated and tested for Phytophthora ramorum. More Info
Like other states that have discovered the presence of "Phytophthora ramorum" in botanicals in their area, Maryland is taking a proactive approach to possible infection of plants in the State. The Maryland Department of Agriculture is very much involved with prevention efforts. More Info
Dr. David Clement, HGICAlso, the University of Maryland has established a line of "first detectors" through training of Maryland Master Gardeners to educate Maryland citizens about the possible infection of nursery plants such as azaleas, rhodendrons, and camellias. Training of Master Gardeners in the southern Maryland area took place on June 20, 2005. Dr. David L. Clement, Senior Agent, Plant Pathologist, and Director of MCE's Home and Garden Information Center (photo on right), provided four hours of instruction in the identification, control, and specimen submission procedures for southern Maryland Master Gardeners. He advised three plant nurseries in Maryland were found to have infected stock that was radiaticated. He emphasized the proper procedures for identifying P. ramorum and submitting plant materials for testing for the pathogen and encouraged Master Gardeners to be proactive when diagnosing plant disease on botanicals submitted by the public.
For more information, contact Carole Butler
Last updated: 06/27/2007
