As research has continued, the list of plants known to be susceptible to P. ramorum has expanded. An up-to-date host list is available at http://www.suddenoakdeath.org. Table 1-2 lists native trees, shrubs, and herbaceous plants that have been found with P. ramorum infections on leaves or twigs under field conditions. These hosts develop minor to significant canopy dieback, but are not killed by P. ramorum.
Table 1-2—California native forest species that develop Phytophthora ramorum leaf or twig infections (foliar hosts)
| Scientific name | Common name |
| Abies concolor1 | White fir |
| Abies grandis1 | Grand fir |
| Abies magnifica1 | Red fir |
| Acer circinatum1 | Vine maple |
| Acer macrophyllum | Bigleaf maple |
| Adiantum aleuticum | Western maidenhair fern |
| Adiantum jordanii | California maidenhair fern |
| Aesculus californica | California buckeye |
| Arbutus menziesii | Pacific madrone |
| Arctostaphylos columbiana1 | Hairy manzanita |
| Arctostaphylos manzanita | Whiteleaf manzanita |
| Berberis diversifolia (= Mahonia aquifolium)1 | Oregon-grape |
| Calycanthus occidentalis1 | Spicebush |
| Ceanothus thyrsiflorus1 | Blueblossom |
| Clintonia andrewsiana1 | Andrew’s clintonia bead lily |
| Corylus cornuta1 | California hazelnut |
| Dryopteris arguta1 | California wood fern |
| Frangula californica (=Rhamnus californica) | California coffeeberry |
| Frangula purshiana (=Rhamnus purshiana) | Cascara |
| Fraxinus latifolia1 | Oregon ash |
| Garrya elliptica1 | Silk tassel tree , coast silktassel |
| Gaultheria shallon1 | Salal, Oregon wintergreen |
| Heteromeles arbutifolia | Toyon |
| Lonicera hispidula | California honeysuckle |
| Mahonia nervosa | Creeping Oregon grape |
| Maianthemum racemosum (=Smilacina racemosa) | False Solomon’s seal |
| Osmorhiza berteroi1 | Sweet Cicely |
| Phoradendron serotinum subsp. macrophyllum2 | Mistletoe |
| Pseudotsuga menziesii var. menziesii | Douglas fir |
| Rhododendron spp. | Rhododendron |
| Rosa gymnocarpa | Wood rose |
| Rubus spectabilis1 | Salmonberry |
| Sequoia sempervirens | Coast redwood |
| Taxus brevifolia1 | Pacific yew |
| Torreya californica1 | California nutmeg |
| Toxicodendron diversilobum1 | Poison oak |
| Trientalis latifolia | Western starflower |
| Umbellularia californica | California bay, California laurel, pepperwood, Oregon myrtle |
| Vaccinium ovatum | California huckleberry |
| Vancouveria planipetala1 | Redwood ivy, redwood insideout flower |
Source: U. S. Department of Agriculture, Animal and Plant Health Inspection Service 2012
1Plants have been found naturally infected, and P. ramorum has been cultured and/or detected using PCR, but Koch's postulates (formal proof of pathogenicity) have not been completed as of Feb 2012
2Riley and Chastagner 2011.