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Chileno Valley Oaks, Dana Hooper



Agri-fos is used to increase the plant's resistance to infection. If the plant is in the early stages of infection, Agri-fos may delay to onset of symptoms.

There is no cure for Sudden Oak Death, and there is no chemical available to kill the fungus. The best we can do is improve the tree's resistance.

Agri-fos is applied during the late fall or winter, and must be applied on an annual basis. For this reason, limit Agri-fos applications to high value trees.


Sudden Oak Death (SOD)
is a new, but widespread disease, affecting portions of europe, the eastern United States and central California. The effects of Sudden Oak Death were first noted in California in the mid-1990's, and the fungus Phytophthera ramorum was first identified in 2001.

For more background information, please refer to:

Plants Affected by Sudden Oak Death (SOD)


Services by Pacific OpenSpace, Inc.

Remove Plants that Spread the Disease
Pacific OpenSpace helps you reduce the spread of Sudden Oak Death. An important strategy is to remove plants that may spread the disease to your oaks. The most common plant to remove is California Bay (Umbellularia californica). Rhododendron is another plant known to spread the disease. It is common in landscapes, but infrequent in natural areas. We keep current with the latest research on Sudden Oak Death. If other plants are identified as significant disease vectors, we will control them as well.

Site Management
Spores in wet soil can splash up onto branches during the winter. One theory is that these spores can infect the plant. This idea has not yet been proven or disproven. It is prudent, however, to trim up oak branches that are close to the ground, so that Phytophthera spores cannot splash up onto the foliage.

It is also worthwhile to open up the stand to improve air circulation. It is possible that allowing better air movement will reduce the period of time that surfaces are wet, during which Phytophthera spores could infect the plant.


California Oak Mortality Task Force
US Department of Agriculture - APHIS