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Tuesday - December 16, 2008

From: Pasadena, CA
Region: California
Topic: Trees
Title: Trees resistant to Armillaria mellea, root fungus
Answered by: Nan Hampton


We had to bring down a 200 year old oak which root system was compromised by Armillaria mellea. We were told the fungus is still present in the soil & it's advisable to plant a resistant species. We're looking to find a native (or non-invasive) faster growing tree that will do well in the hotter and hotter climate of the region and be able to shade the south east face of our house. Any recommendations?


First of all, here is information about Armillaria mellea and similar fungi from the  U. S. Forest Service, Forest Pathology.org and the Integrated Hardwood Range Management Program of the University of California Extension.  The U.S. Forest Service and Forest Pathology recommend removing stumps and as many of the roots as possible of affected trees before planting new trees.  All three of the sources above agree that the use of resistant species is one of the most effective means of controlling the fungus.

The University of California Davis has a list of plants that are highly resistant to Armillaria mellea and there is an extensive list showing plants that are resistant, or susceptible, to Armillaria mellea from Chase Horticultural Research.  Many of the plants on these two lists are not native to California and North America and we would not recommend any of those.  However, here are ones that are native and occur in Los Angeles County, or an adjacent county, that we would recommend:

Acacia farnesiana (sweet acacia)

Fraxinus velutina (velvet ash)

Arbutus menziesii (Pacific madrone) and photo

Prunus ilicifolia (hollyleaf cherry) and photos

Sambucus nigra ssp. canadensis (common elderberry)

Shepherdia argentea (silver buffaloberry)

Acacia farnesiana

Fraxinus velutina

Sambucus nigra ssp. canadensis

Shepherdia argentea




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