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Sudden Oak Death -Alert

As a follow up to the MNLA's e-mail to the membership on the evening of Wednesday, March 17th, we have updated information about the potential introduction of plants infected with the Sudden Oak Death fungus, P. ramorum. The following is a communication from the Maryland Department of Agriculture, combined with additional anticipated questions and answers.

The California Department of Food and Agriculture (CDFA) has confirmed the presence of Phytopthora ramorum in camellia and viburnum at two southern California locations, Monrovia Nursery, Azusu, and Specialty Plants in San Diego County. Suspect plant material was shipped to Maryland in 2003 and 2004.
The pathogen Phytophthora ramorum is responsible for the diseases known as Sudden Oak Death and Ramorum blight. These diseases were first observed in Europe and California around 1993. The host range forP. ramorum is incomplete, but there are at least 58 regulated and associated hosts. The pathogen would be devastating to woody plants in both landscaped and natural areas if it became established in Maryland.

Additionally, CDFA has tested plants from other California nurseries as part of their P. ramorum survey. Samples from eleven other locations have tested positive with PCR for P. ramorum. There is a 90% chance that these PCR positives will be confirmed by culturing. As a precaution, we recommend that all nurseries and plant dealers isolate and hold plant material from California. This will prevent nurseries, plant dealers, and landscapers from selling infected plants.

As a result of the detection in California, the Maryland Department of Agriculture will be visiting establishments that have received host materials from Monrovia Nursery in California over the past twelve months. Our nursery inspectors will be visiting these locations in the next few weeks to examine plants, collect samples, and place holds on suspect material. It is likely that the list of Maryland nurseries to be visited will expand as test results become available and other California facilities are implicated. MDA will be testing plants at our Plant Pathology laboratory in Annapolis.

If you would like more information about testing or are interested in having plants at your nursery sampled, please contact MDA at 410-841-5920. If you are not familiar with the symptoms caused by P. ramorum or would like to view the host list, please visit the California Oak Mortality Force Website or the USDA, APHIS, PPQ website. The North Central IPM Center Sudden Oak Death National Pest Alert

Common Questions (answers summarized from communications with MDA and the National Pest Alert on Sudden Oak Death, published by USDA Regional Pest Management Centers):

What are the symptoms of Sudden Oak Death?
Bark canker hosts infected with P. ramorum have large cankers on the trunk or main stem accompanied by browning of leaves. Tree death may occur within several months to several years after initial infection. Infection on foliar hosts is indicated by dark grey-to-brown lesions with indistinct edges. These lesions can occur anywhere on the l eaf blade, in vascular tissue, or on the petiole. Petiole lesions are often accompanied by stem lesions. Some hosts with leaf lesions defoliate and eventually show twig dieback. Infected plants will begin to show spores and spoil symptoms in the spring - within the next few weeks. Cultures to determine possible infection, however, can be performed on plants before symptoms show.

How does the disease spread in the nursery?
The spread of SOD likely occurs through infected plant material, rainwater, and soil. The fungus releases spores, which may be carried via wind, water, tools (such as pruning shears), clothes, etc.

Can non-host plants be disease vectors if they shared space on the truck with infected plants?
Theoretically, non-host plants could serve as disease vectors, through passing on of spores. The risk of this happening, however, is unknown.

What are recommended handling and sanitary instructions for dealing with suspect plants?
If you suspect trees or plants are infected with P. ramorum, contact the MDA immediately at 410-841-5920. In the mean time, suspect material should be separated from non-suspect stock. Suspect stock should be totally removed from any sales area to prevent unintended sale.
Overhead watering of suspect stock should be avoided, as spores may be spread through water droplets. In addition, all tools and equipment used on suspect stock should be thoroughly cleansed after use.
A listing of plant species known to be host to P. ramorum follows at the end of this newsletter.

Emerald Ash Borer - Update

Secretary of Agriculture, Lewis Riley, issued a quarantine on March 17th, prohibiting the movement of ash trees and materials into, out of, or through the area in southern Prince George's County that received ash trees infected with emerald ash borer in the spring of 2003. Over the next several weeks, the MDA will destroy approximately 500 ash trees within ˝ mile radius of Ed's Plant World, in Brandywine, the unsuspecting recipient of the infected trees. For more information about EAB and the quarantine, please refer toMD Invasive Species Website.

Plant species regulated for Phytophthora ramorum (these are regulated in whole or in part - see APHIS Website)

Scientific Name

Common Name
Acer macrophyllum Bigleaf maple
Aesculus californica California buckeye
Arbutus menziesii Madrone
Arctostaphylos manzanita Manzanita
Camellia japonica Japanese c amellia
Camellia sasanqua Sasanqua camellia
Hamamelis virginiana Witch hazel
Heteromeles arbutifolia Toyon
Lithocarpus densiflorus Tanoak
Lonicera hispidula California honeysuckle
Pieris formosa Himalaya pieris
Pieris formosa x japonica Pieris 'Forest Flame'
Pieris floribunda x japonica Pieris 'Brouwer's Beauty'
Pieris japonica Japanese pieris
Pseudotsuga menziesii var. menziesii Douglas-fir
Quercus agrifolia Coast live oak
Quercus chrysolepis Canyon live oak
Quercus kelloggii California black oak
Quercus parvula v. shrevei Shreve oak
Rhamnus californica California coffeeberry
Rhododendron spp Rhododendron
Sequoia sempervirens Coast redwood
Trientalis latifolia Western starflower
Umbellularia californica California bay laurel
, pepperwood,
Oregon myrtle
Vaccinium ovatum Evergreen huckleberry
Viburnum x bodnantense Bodnant viburnum
Viburnum plicatum var. tomentosum Doublefile viburnum
Viburnum tinus Laurustinus


Plant species associated with P. ramorum, not currently regulated

Scientific Name

Common Name

Date & Source of Report
Abies grandis Grand fir June 03 (1)
Aesculus hippocastanum Horse-chestnut Dec 03 (3)
Arbutus unedo Strawberry tree Dec 02 (7)
Camellia reticulata Oct 03 (3)
Camellia x williamsii Oct 03 (3)
Castanea sativa Sweet Chestnut Feb 04 (3)
Corylus cornuta California hazelnut Dec 02 (5)
Fagus sylvatica European beech Dec 03 (3)
Kalmia latifolia Mountain laurel Fall 02 (3)
Leucothoe fontanesiana Drooping leucothoe Oct 03 (3)
Pieris formosa var. forrestii Chinese pieris Oct 03 (3)
Pieris formosa var. forrestii x Pieris japonica Oct 03 (3)
Pittosporum undulatum Victorian box Dec 02 (6)
Quercus sativa European turkey oak Feb 04 (3)
Quercus falc ata Southern red oak Nov 03 (3)
Quercus ilex Holm oak Dec 03 (3)
Quercus rubra Northern red oak Nov 03 (8)
Rhamnus purshiana Cascara
Rubus spectabilis Salmonberry Dec 02 (4)
Syringa vulgaris S Lilac 2003 (3) updated Oct 03
Taxus baccata European yew (3)
Toxicodendron diversiloba Poison oak Dec 02 (4)
Vaccinium vitis-idaea - Lingonberry Poland, 2002 (reported by 3)
Viburnum davidii David viburnum Oct 03 (3)
Viburnum farreri (=V. fragrans) Fragrant viburnum Oct 03 (3)
iburnum lantana V Wayfaringtree viburnum Oct 03 (3)
Viburnum opulus European cranberrybush viburnum Oct 03 (3)
Viburnum x burkwoodii Burkwood viburnum Oct 03 (3)
Viburnum x carlcephalum x V. utile Oct 03 (3)
Viburnum x pragense Prague viburnum Oct 03 (3)

location key

1 California Department of Food and Agriculture 2 Oregon Department of Agriculture 3 Department for Environment, Food, and Rural Affairs, UK 4 Everett Hanson, Oregon State University 5 David Rizzo, University of California - Davis 6 Mateo Garbelotto, University of California - Berkeley 7 Eduardo Moralejo, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB) - Balearic Islands, Spain 8 Plant Protection Service, Wageningen, Netherlands

Rationale for lists:

Plant species regulated for Phytophthora ramorum: Regulated plants are those adapted from other regulated lists or were added upon completion, documentation and review of traditional Koch's postulates. Some are regulated in part (such as redwood and Douglas fir), others are regulated in their entirety (such as tanoak and western star flower). Details on regulated articles can be found via links to "Phytophthora ramorum 7 CFR 301.92" and "Recent Modifications to Phytophthora ramorum Regulations" at: The APHIS Web Site Plant species associated with P. ramorum, not currently regulated: Associated plants are those found naturally infected from which P. ramorum has been cultured and/or detected using PCR (Polymerase Chain Reaction). For each of these, traditional Koch's postulates have not yet been completed or documented and reviewed. Though not regulated and not requiring certification under P. ramorum regulations, these plants will be inspected in nurseries and Christmas tree plantations and, if symptoms observed, held from sale pending testing. This list is constantly being updated. The most current version is posted at: The APHIS Web Site Regards,

The MGGA Board of Directors updated March 22, 2004
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