ÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝ Forest Plant Pathology & Public Policy:
A Summary of Selected Topics involving the Phytophthera species linked to SOD
Despite a plethora of media articles[1],
the scientifically literate reading public is probably unaware that the
pathogen species of current record is botanically classified as more algae-like
than fungous, that the most commonly infected oak being ìravagedî, the tanoak,
is not a true oak, and that some serious scientists are currently of the
opinion that there is unlikely to be any quick and easy solution to the problem
which will likely run its course over time.[2]
So what is one to make of all the tech-talk about
resting chlamydospores, invading zoospores, proliferating sporangia,
therapeutic phosphonate, and multi-disciplinary crisis generated task forces on
a mission of mercy?Ý The answer is a
tale of a typical California policy issue this time characterized by a Marin
Co. led crisis mode media blitz, formation of the obligatory Task Force, and a rush
to Sacramento for Assembly funding.
Background:
Phytophthera is a mold,
mildew,Ý blight and opportunistic
fungalÝ genus with at least 70 species.
Many of the species are the infecting agent of many forms of root rot what are
well know to agriculturalist, nurserymen, horticulturalists, arborists and
naturalists with a respect for history.Ý
For example, during the 19th century, a water mold known as the late
potato blight (Phytophera
infestans) decimated Ireland's potato crops,Ý
root rot effects plants as diverse as taro, soybeans, roses, raspberries,
rhodedendrons and Port Orford Cedar.
SOD is identified
as starting in Mill Valley, Marin Co. in 1995 in tanoak. Since then its range
is thought to extend from Sonoma Co to Big Sur.Ý The effect has been to raise the specter of an infectious epidemic
among native oak woodland species, a potential fire fuel overload and a threat
to some of this highest priced residential real estate in the county than has
been horticultural adorned with both native and imported exotic plant species.Ý Suseptible native species are thought to include Ýhuckleberry
(Vaccinium ovatum), Shreve's
oak (Quercus parvula var. shrevei), bay
laurel (Umbellularia californica), and madrone
(Arbutus menziesii[3]
ÝRecently riding to rescue is Matteo Gabelotto a forest pathologist
hired one year ago by the UC Cooperative Extension Service to work in the Lab
of Dr. Chapella on the Berkeley campus.Ý
He is reported to be the product of an aristocratic and cultured Italian
family who sports a first rate C.V. with strengths in molecular biology, and a
cosmopolitan perspective and life style suited to the most discriminating of
city and suburban chardonnay tastes.Ý
One of his primary collaborators is Paul Risso, a Plant Pathologist at
UCDavis. And they are part of The California Oak
Mortality Task Force (COMTF). COMTF has a six-member board and seven standing committees:
Education,
Fire Prevention, Funding, Management, Monitoring, Regulation, and Research. Represented are County Commissioners,
Public Relations specialists, State of California Foresters, USDA Forest
Service professionals, Cooperative Extension Agents and Administrators,
nonprofit NGO fund raising specialists, University of California Entomologists,
and various Liaisons.
What Phytophthera looks like under the Microscope:
How
Phytophera Attacks:
Ý
Ý Theories of spread include raindrops, soil, imported
species, mulch, wind and spontaneous generation.Ý The site of attack is primarily above ground, and penetration
through bark is thought beÝ by enzymatic
action, the cambial layer demonstrates signs of infestation. Signs include
bleeding cankers, leaf spots, and stem spots depending on the host species.
Beetles are prominent secondary invaders of infected trees.[4].
ÝSample Actions to Date: as ofÝ 4/2001[5]
The State of Oregon has made a temporary
quarantine on the importation of potentially infected nursery stock and mulch
permanent. There has been discussion in some quarters of the state to
reactivate the Unwelcome Signs at the southern border from the era ofÝ Governor Tom McCall era to all
CaliforniaÝ visitors who might have
Marin County plant material or soil on their shoes. This has been called by
some, payback for recently announced and unprecedented preference for mullet
and Coho claims to Klamath Co agricultural irrigation water at the headwaters
of the Klamath River by the Bureau of Reclamation and U.S.Fish and Game.Ý Their abrogation of a near 100 year contract
with farmers, many of them WW II Cal Vets whose first homes were internment
sheds, was made after the potato, onion, wheat, barley, and Alfalpha seed was
sown in the sandy soil.
Canada has imposed a
quarantine prohibiting the import of nursery stock and unmanufactured
non-propagative material (logs, mulch, etc.) of all oaks (Quercus,) tanoak (Lithocarpus),
Rhododendron spp. and evergreen
huckleberry (Vaccinium ovatum) and
have soil from areas where sudden oak death occurs. This measure was taken to
prevent the entry into Canada of this potentially injurious pest. The ban
covers Germany, the Netherlands and the 7 counties that have SOD in CA.
The measure went into effect March 9, 2001.
Matteo Garblotto, has demonstrated that phosphonate injected into sapling coast
live oak can arrest the growth of SOD cankers. These results are
preliminary and there is much work needed before phosphonate can legally be
used as a treatment for ornamental trees. Phosphonate is a fertilizer and is not registered for use as a
fungicide. It needs to have toxicology work done and further efficacy
testing before it can be registered for use in CA.
The California Assembly version of the $10 million spending plan for Sudden Oak Death was heard by the Assembly Appropriation Committee on April 4 It was approved into suspense file. ACR 5, a joint resolution in support of the addressing Sudden Oak Death in CA and of the CA Oak Mortality Task Force has been approved to the consent calendar.
Summary:
This brief report
is intended to be this lay personís starting point for some thoughts and recent
experiences on the subject matter. It is part of other 2001 SRJC intersession
material posted at www.oslerbooks.com/forest.
Doug Fisk
For Steve Barnhart