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Mr. Smarty Plants - Oak root resistant hedge for Southern California

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Saturday - December 28, 2013

From: Los Angeles, CA
Region: California
Topic: Diseases and Disorders, Privacy Screening
Title: Oak root resistant hedge for Southern California
Answered by: Nan Hampton

QUESTION:

I live in Southern California and my cypress hedge has oak root fungus. What kind of hedge can I plant that will grow fast and be resistant to the fungus?

ANSWER:

Las Pilitas Nursery, located in Santa Margarita and Escondido, has an article, Hedges, Windbreaks, and Screens with California Native Plants and Theodore Payne Foundation for Wildflowers and Native Plants, Inc. in Sun Valley has an article, Plants Resistant to Oak Root Fungus.

Considering both of the above lists, here are selections that are listed by Theodore Payne Foundation as being "Immune" to the oak root fungus.  They are the evergreen trees or shrubs on the list.

Mahonia aquifolium (Hollyleaved barberry) grows 3 to 6 feet high and Mahonia nevinii (Nevin's barberry) grows 5 to 12 feet high.  [Note that the synonyms for these two use the genus name, Berberis, instead of Mahonia.]  Here is more information about Hollyleaved barberry from Las Pilitas and from Theodore Payne Foundation and here is more information about Nevin's barberry from Las Pilitas Nursery and from Theodore Payne Foundation.

Carpenteria californica (Bush anemone) grows 4 to 8 feet high.  Here is more information from Theodore Payne Foundation and from Las Pilitas Nursery.

Prunus ilicifolia (Hollyleaf cherry)  or Prunus ilicifolia ssp. lyonii (Catalina cherry) grows 10 to 40 feet.  Here is more information from Las Pilitas Nursery and Theodore Payne Foundation.

Calocedrus decurrens (Incense cedar) grows slowly to 60 feet.   Here is more information from Missouri Botanical Garden and Theodore Payne Foundation.

There are certainly species on the Las Pilitas Nursery list that are not named on the Theodore Payne Foundation list.  The Arctostaphylos spp. (Manzanitas) are moderately resistant to the fungus; but here are some evergreen hedge species on the Las Pilitas "Hedges, Windbreaks, and Screens with California Native Plants" list to avoid:

There is another list, Plants Resistant or Susceptible to Armillaria mellea, The Oak Root Fungus, by Robert D. Raabe from the University of California, Berkeley that does include some California native plants.   However, a majority of the plants on the list are not native and, indeed, some are invasive species [e.g., Melia azerdarach (Chinaberry or Persian lilac)] so unless you check each species for its nativity and invasiveness, you should use caution in using for picking a substitute for your cypress hedge.  Here are a few choices from that list, however, that I have checked for nativity and invasiveness:

Garrya elliptica (Wavyleaf silktassel) grows to 10 feet and is evergreen.   Here is more information from Las Pilitas Nursery and Theodore Payne Foundation.

Calycanthus occidentalis (Western sweetshrub) grows to 15 feet, is deciduous but a fast grower.   Here is more information from Theodore Payne Foundation and from Las Pilitas Nursery.

Shepherdia argentea (Silver buffaloberry) is decidous, grows to 6 to 20 feet with spiny twigs.   Here is more information from Theodore Payne Foundation and from Las Pilitas Nursery.  The growth rate has been described as rapid to moderate.

 

From the Image Gallery


Hollyleaved barberry
Mahonia aquifolium

Nevin's barberry
Mahonia nevinii

Bush anemone
Carpenteria californica

Catalina cherry
Prunus ilicifolia ssp. lyonii

Western sweetshrub
Calycanthus occidentalis

Silver buffaloberry
Shepherdia argentea

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