Plants Resistant to Oak Root Fungus

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Compiled by the Theodore Payne Foundation for Wildflowers and Native Plants, Inc.

 

Armilleria root rot is one of the most damaging diseases of trees and shrubs around the world. Symptoms of infection include reduction in growth, yellowish or undersized foliage, premature leaf drop, branch dieback in the upper crown, and rapid browning and death of the entire plant during summer. Larger plants may survive for a long time in a chronically diseased state. The mushroom (spore-producing) stage of the fungus develops annually in autumn and the first part of winter, as mushrooms appear on or near wood that is undergoing decay. To minimize the risk of developing Armilleria, care properly for oaks. Avoid summer water and do not under plant within 6 to 10 feet on either side of the trunk.

KEYS TO FLOWER COLOR:

B

blue

R

red

KEY TO RESISTANCE LEVEL:

  

G

green

V

violet/purple

1

Immune

O

orange

W

white

2

Highly Resistance

P

pink

Y

yellow

3

Moderately Resistance

 

 RESISTANT TREES

  • 1   Abies concolor, White Fir  –gorgeous tree, best at higher elevations; give shade in hot situations

  • 1   Acer macrophyllum, Big-leaf Maple

  • 2   Acer negundo, Box Elder

  • 1   Calocedrus decurrens, Incense Cedar – aromatic conifer with upright pyramidal form; easy to grow

  • 1   Cercis occidentalis, Western Redbud

  • 2   Chamaecyparis lawsoniana, Port Orford Cedar

  • 1   Fraxinus velutina, Arizona Ash

  • 1   Juglans californica, S. California Black Walnut and J. hindsii, N. California Black Walnut

  • 1   Pinus radiata, Monterey Pine and P. torreyana, Torrey Pine

  • 3   Platanus racemosa, Western Sycamore

  • 2   Pseudotsuga menziesii, Douglas Fir

  • 1   Sequoia sempervirens and selections, Coast Redwood
RESISTANT SHRUBS
  • 3   Arctostaphylos spp., Manzanita  P/W

  • 1   Berberis aquifolium, Oregon Grape and B. nevinii, Nevin’s Barberry Y

  • 1   Calycanthus occidentalis, Spice Bush R

  • 1   Carpenteria californica, Bush Anemone W

  • 2   Cephalanthus occidentalis, Button Willow  W

  • 3   Philadelphus lewisii, Mock Orange W

  • 1   Prunus ilicifolia, Holly-leaf Cherry and P lyonii, Catalina Cherry W

  • 2   Prunus virginiana demissa, Western Chokecherry W

 

SUSCEPTIBLE TREES AND SHRUBS (avoid):

Ceanothus spp., California Lilac  B/V/W;  Fremontodendron spp. and selections  Y; Heteromeles arbutifolia, Toyon, Christmas Holly W;  Lithocarpus densiflora, Tanbark Oak; Rhus ovata, Sugar Bush  P/W; Sequoiadendron giganteum, Giant Sequoia; Thuja plicata, Canoe Cedar