About Sudden Oak Death

Transcription

1 About Sudden Oak Death What's on this page? Description of Sudden Oak Death Regulated and Associated Plants General Plant Symptoms Map of Current Disease Distribution Disease Chronology Description of Sudden Oak Death Sudden Oak Death is a forest disease caused by the fungus-like pathogen Phytophthora ramorum. This pathogen has caused widespread dieback of tanoak and several oak species in the central and northern coastal counties of California, and has to date been associated with 26 different plant species. While some of these species - coast live oak, black oak, Shreve oak and tanoak - sustain lethal trunk infections, other plants get more benign foliar and twig infections. Many of these species with foliar infections play a key role in spread of P. ramorum by acting as a reservoir of innoculum, which may then be spread aerially via wind blown rain. Sporangia and chlamydospores, the most likely propagules of dispersion, are commonly generated on foliage, whereas they have not as yet been found on infested oak bark. The two plants determined to be the greatest sinks for innoculum are California bay laurel/oregon myrtle and Rhododendron spp. Mortality is most common where oaks and these foliar hosts are found growing together. At present, there are 26* species known to be susceptible to the Phytophthora ramorum. 19 of these have been recognized as regulated hosts by the United States Department of Agriculture, Animal and Plant Health Inspection Service - Plant Protection and Quarantine (USDA-APHIS-PPQ), and by the California Department of Food and Agriculture (CDFA). These species are now listed in Phytophthora ramorum 7 CFR Part 301, the interim rule published on by APHIS, identifying what materials are regulated and how. An additional 7 plant species are listed as associated with Phytophthora ramorum. Associated plants are those which have been naturally infected with he pathogen in the field, but which have not yet been listed by the regulatory agencies as hosts.

2 Regulated Hosts Scientific Name Acer macrophyllum Aesculus californica Arbutus menziesii Arctostaphylos manzanita Heteromeles arbutifolia Lithocarpus densiflorus Lonicera hispidula Pseudotsuga menziesii Quercus agrifolia Quercus chrysolepis Quercus kelloggii Quercus parvula v. shrevei Rhamnus californica Rhododendron spp Sequoia sempervirens Trientalis latifolia Umbellularia californica Vaccinium ovatum Viburnum* Common Name Big leaf maple California buckeye Madrone Manzanita Toyon Tanoak California honeysuckle Douglas-fir Coast live oak Canyon live oak California black oak Shreve oak California coffeeberry Rhododendron Coast redwood Western starflower California bay laurel Huckleberry Arrow wood Associated Plant Species Scientific Name Camellia* ** Corylus cornuta** Rhamnus purshiana** Pierus** Pittosporum undulatum** Rhus diversiloba** Rubus spectabilis Common Name Camellia California hazelnut Cascara Pierus Victorian box Poison oak Salmonberry *Camellia and Viburnum are both known to be susceptible in Europe but have not as yet been observed as naturally infected in the United States. ** California hazelnut, Cascara, Pierus, poison oak, Victorian box, and Camellia are plants associated with P. ramorum. To date, however, these plants have not been confirmed as hosts.

3 General plant symptoms Depending on the plant species, infection may occur on the trunk, branches, and/or leaves. Infections on woody portions of the tree are referred to as cankers. Cankers on the trunk of oak trees are the most damaging. Tree death appears to occur when cankers expand in the trunk (girdling) and disrupt physiological function. Diseased oaks are often attacked by other pest organisms -- fungi that decay sapwood (Hypoxylon thourasianum) and bark beetles. In the shrub species the symptoms can range from leaf spot to twig girdling, and do not necessarily result in death of the plant. (See SOD Diagnostic Guide at for more specific information). Phytophthora ramorum appears to thrive in cooler, wetter climates. In California, it is found only in the coastal counties (see map below). The means of dispersal include wind blown rain splash and infested plant material. Plants infected with P. ramorum had been observed in 12 counties along the west coast of California. Those counties are, from north to south: Humboldt, Mendocino, Sonoma, Napa, Solano, Marin, Contra Costa, Alameda, San Mateo, Santa Clara, Santa Cruz, and Monterey. The map below shows the current distribution of the pathogen in California by county, and supports the notion that it tends to thrive in moist micro-climates like those found along the western coast of the state.

4 In addition to California, the pathogen has been seen in Curry County in the southwestern corner of Oregon, where it is undergoing eradication. In Europe, P. ramorum has been identified on plants in Germany, Spain, France, Poland, Belgium, Sweden, Italy, the Netherlands, and the United Kingdom. It should be noted that on some of the affected species the symptoms are hard to detect, or to differentiate from those of other pathogens. For this reason you are encouraged to contact your county's Cooperative Extension or Agricultural Commissioner's office for help with identification of hosts, determining the presence of the pathogen, or sampling the plant.

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6 A CHRONOLOGY OF PHYTOPHTHORA RAMORUM, CAUSE OF SUDDEN OAK DEATH AND OTHER FOLIAR DISEASES 01/03 P. ramorum is isolated from Camellia in a nursery in the UK. 12/02 P. ramorum is isolated from over 150 nurseries in the UK. France, Belgium, Netherlands, Sweden, Italy, Germany and other European countries also report widespread infestations. First Sudden Oak Death Science symposium is held in Monterey. Over three hundred people attend. Eight new plants associated with P. ramorum are announced: California Hazel, poison oak, salmonberry, cascara, Victorian box, and Pieris (the last from nursery stock in UK). Everett Hansen, OSU along with Rizzo and Garbelotto name another new Phytophthora found on dying oaks and infecting leaves of California bay laurel. Phytophthora nemorosa has a similar geographic range as P. ramorum but is considered less virulent. The P. ramorum isolates from Europe are determined to be a different mating type from those isolated in California indicating that the pathogen did not come from Europe to California or vice-versa. 11/02 Scientists at the U.S. Department of Energy's Joint Genome Institute in Walnut Creek and the Virginia Bioinformatics Institute in Blacksburg are receiving $3.8 million from Federal agencies to decode and study the genomes of Phytophthora ramorum and Phytophthora sojae. The European Union issues regulations for P. ramorum. 10/02 The Canadian Food Inspection Agency adds a certification program to their Phytophthora ramorum regulations allowing shipments of fieldgrown plants into Canada from uninfested counties of California following

7 9/02 7/02 5/02 4/02 inspection. Phytophthora ramorum found on two shipments of rhododendron in Spain. Australia introduces regulations preventing the import of host species from countries known to have Phytophthora ramorum. CDFA and USDA-APHIS added only the affected plant parts of Coast redwood and Douglas-fir to state and federal quarantines. Governor Davis's administration supports SOD research and response with a $2 million commitment in 2002/03 State budget. UC Researchers confirm Coast redwood and Douglas-fir are susceptible to Phytophthora ramorum. Humboldt and Contra Costa Counties are confirmed to have Phytophthora ramorum. Two informational meetings held for resource professionals in Humboldt county hosted by UCCE, 175 attendees. United Kingdom bans imports of plants and wood from parts of U.S. to prevent spread of Sudden Oak Death. Poland's Phytophthora ramorum findings on rhododendron plants in nursery setting are reported to the U.S. England confirms Phytophthora ramorum findings on Viburnum tinus in nursery setting. The scope of infestation includes 15 known host species, 10 confirmed counties, and the following eight state parks: Austin Creek State Recreation Area, China Camp State Park, Jack London State Park, Pfeiffer

8 Big Sur State Park, Samuel P. Taylor State Park, Sugarloaf Ridge State Park, Henry Cowell Redwoods State Park, and Mt. Tamalpais State Park. 3/02 2/02 1/02 Media reports that Phytophthora ramorum DNA has been detected on maple in Foresthill, Placer County (furthest inland finding of Sudden Oak Death). Unless samples are cultured, Placer County will not be classified as a regulated county. Assemblypersons Nation and Migden introduce AB2251 to continue California's Sudden Oak Death program. First of two public hearings is held in Petaluma on interim APHIS Sudden Oak Death regulations. USDA Animal Plant Health Inspection Service (APHIS) releases interim federal regulations for Sudden Oak Death. These regulations will oversee interstate movement of host material. Media reports that Phytophthora ramorum has been detected on redwood. Unless isolates are cultured from samples, redwood will not be classified as a host. 12/01 11/01 Senator Boxer announces $400,000 in agricultural appropriations for Sudden Oak Death research. Marin County Supervisor Cynthia Murray convenes the second Sudden Oak Death Summit. Phytophthora ramorum confirmed on UC Berkeley campus.

9 10/01 9/01 8/01 7/01 6/01 China Camp Back Ranch Campground closes to remove and destroy about 80 hazardous trees. Park trails have another 70 potentially hazardous trees to remove. Alameda and Solano Counties are added to the ZOI by the BOF after confirmation from CDFA that both counties have Sudden Oak Death and are now regulated counties. California coffeeberry, Toyon, and California honeysuckle are confirmed as new hosts. COMTF issues sampling guidelines for Phytophthora ramorum. CDFA defines and requires "official" samples for regulatory purposes. The Legislature passes, and Governor Davis signs, AB 62 (Migden) authorizing funding and spending based on task force recommendations. Funds are allocated as follows: monitoring $440,000; management $1,796,000 earmarked largely for affected counties; research $480,000; education $221,000; regulation $420,000; and administration $243,000. South Korea imposes a quarantine on oak products from California. Oregon identifies and confirms Sudden Oak Death in Curry County. Infected areas are quarantined and under regulation. Plans for eradication of host material begins. Governor Davis and the Legislature provide $3.586 million to address Sudden Oak Death in the 2001/02 budget. Senator Boxer introduces a bill in the US Senate calling for $70 million to address Sudden Oak Death. Congresswoman Woolsey introduces a similar bill in the House of Representatives.

10 5/01 4/01 3/01 2/01 1/01 The California Department of Food and Agriculture issues emergency regulations that require permits to be issued by an authorized agricultural official to move host plants or materials within or from infested areas. Researcher Matteo Garbelotto develops a molecular diagnostic tool using polymerase chain reaction (PCR) to identify the presence of Phytophthora ramorum. Phytophthora ramorum is recovered from madrone and bay laurel. The Board of Forestry and Fire Protection (BOF) passes a resolution declaring a "Zone of Infestation" (ZOI) for the counties of Marin, Monterey, Napa, San Mateo, Santa Clara, Santa Cruz, and Sonoma. In July 2001, the zone is expanded to include Mendocino County after confirmation by the California Department of Food and Agriculture (CDFA). Canada issues Sudden Oak Death quarantine. Researchers recover Phytophthora ramorum from rainwater collected beneath coast live oak stem infections and from soil collected around diseased coast live oak. Huckleberry and Shreve oak are confirmed as Phytophthora ramorum hosts. Phytophthora ramorum is recovered from rhododendron plants in a Santa Cruz nursery. Oregon institutes a quarantine that bans wood from California hosts that have not been kiln dried. This is an interim rule good for 90 days.

11 The Federal government appropriates $3.5 million for Sudden Oak Death research and monitoring. 12/00 State legislators introduce bills to establish a statewide program to address Sudden Oak Death: SB31 (Chesbro); AB53 (Wiggins); AB62 (Migden); and ACR (Nation). 11/00 Marin County Supervisor Cynthia Murray convenes the first Sudden Oak Death Summit. The United States Department of Agriculture (USDA) Undersecretary of Agriculture Jim Lyons pledges $2.1 million in federal funding. Governor Davis pledges $100,000 in state funding through the Department of Forestry and Fire Protection (CDF). 10/00 8/00 7/ The first COMTF general member meeting is held in Vallejo. The theme for the meeting is "What is Sudden Oak Death?" About 150 people, including press attend. The California Oak Mortality Task Force (COMTF) is formed. It is a voluntary consensus group that brings together public agencies, nonprofit organizations, and private interests to address Sudden Oak Death in California in a comprehensive and coordinated manner. U.C. researchers identify the cause of Sudden Oak Death to be a previously unknown forest pathogen: Phytophthora ramorum. Researchers came together to look at the death of oaks and tanoaks in Marin. Emergency funding of $70,000 is provided by U.C. and $85,000 from the USDA Forest Service.

12 1995 Large numbers of tanoaks are observed to be dying in Mill Valley, Marin County. Reports also from Santa Cruz and Monterey.