Oak Death, a serious disease of oaks, caused by Phytophthora
ramorum has NOT been found in Minnesota. However, other Phytophthora
species are causing very serious losses on woody ornamentals in
Minnesota and our research program is identifying these species
using molecular techniques and finding appropriate methods for control.
The highly valued and ecologically important oak population in urban
landscapes and forests of Minnesota is at great risk from the introduction
of Sudden Oak Death and we continue our efforts to look for this
disease on woody plants brought into the state and to do everything
possible to prevent it from getting established.
Many people have heard about Sudden
Oak Death and would like more information. Pioneering efforts on
the etiology of this disease have been carried out by Professor
David Rizzo at the University of California at Davis, a past student
who received his Ph D here in forest pathology. To find out how
to recognize this disease and for general information see the Diagnostic
Guide for Sudden Oak Death. Although Phytophthora ramorum
causes mortality on oak trees in California it also causes branch
and stem cankers, shoot and tip dieback and foliar lesions on other
plants like Rhododendron, Viburnum and Camellia.
Plants that have just foliar symptoms and are shipped to nurseries
in other areas can spread the disease to new locations.
The California Oak Mortality Task
Force web site has excellent information on all aspects of Sudden
Oak Death and the other diseases (branch cankers, shoot dieback
and leaf lesions) that it causes: http://www.suddenoakdeath.org/
Additional information on government
regulations for this disease and up to date lists of plants that
can be affected can be found at: http://www.aphis.usda.gov/ppq/ispm/pramorum/
Each year, woody ornamental nurseries
and home owners throughout the upper midwestern United States lose
countless numbers of shrubs and trees to unknown diseases. One group
causing serious losses is the fungus-like organism called Phytophthora
(the name is derived from the Greek meaning plant-destroyer).
Little research has been done on this pathogen of woody plants in
Minnesota. Our investigations to monitor for Sudden Oak Death have
provided important new information on the Phytophthora
species that are problematic in Minnesota nurseries.
For more information on our research
concerning Phytophthora diseases of woody ornamentals in
Minnesota see our web page: Phytophthora