Appendix D. Symptoms Associated with P. ramorum

Symptoms of 

Phytophthora 

ramorum

Ramorum Foliar 

Blight and 

Dieback

Foliar Blight and Dieback Hosts

Selected Hosts:

- Camellia - Camphor

- Rhododendron - Loropetalum

- Pieris - Osmanthus

- Viburnum - Douglas-fir

- Kalmia (Mountain Laurel) - Grand fir

- Syringa (Lilac)

Page D1
Appendix D. Symptoms Associated with P. ramorum

Camellia

• Symptoms can be subtle –

pinhead lesions

• Look for irregular-shaped brown 

lesions on leaves

• Lesions can be on leaf tips, mid 

vein, edges of leaves

• Leaf drop due to P. ramorum 

infection is common with 

camellias

P. ramorum infected camellia leaves (photos provided by C. Blomquist, CDFA)

Photo: N. Grunwald, USDA ARS Photo: C. Blomquist, CDFA

Page D2
Appendix D. Symptoms Associated with P. ramorum

Camellia

Pinhead lesions

P. ramorum infected camellia, C. Blomquist, CDFA

 

Page D3
Appendix D. Symptoms Associated with P. ramorum

Camellia 

 

 P. ramorum infected camellia leaf, flower buds and leaf petiole, S. Tjosvold

As with other hosts, many of the visual symptoms will occur where water 

tends to collect following irrigation, or on lower plant parts in areas which 

stay wet for longer periods of time.

Some of the images are representative of advanced symptoms which were 

found with greater frequency in the early years of the program. With the 

current surveys and policies, it has become rarer to encounter advanced 

symptoms. As a result, visual surveys have become more challenging and 

may require a more thorough inspection inclusive of lower foliage and 

stems.

As with most hosts, P. ramorum lesions typically extend through the leaf, 

with the lesion appearing identical on the upper and lower surfaces.

Page D4
Appendix D. Symptoms Associated with P. ramorum

Rhododendron

 

 P. ramorum infected rhododendron leaves, S. Tjosvold

 P. ramorum infected rhododendron stems and petioles. Infected rhododendron flower bud.

Photo: J. Parke, OSU Photo: E. Hansen, OSU

Photo: E. Hansen Photo: S. Tjosvold Photo: S. Tjosvold

Page D5
Appendix D. Symptoms Associated with P. ramorum

Pieris

P. ramorum infected Pieris leaves, stems, flowers, N. Osterbauer, ODA

Page D6
Appendix D. Symptoms Associated with P. ramorum

Viburnum

 P. ramorum infested viburnum, Oregon Department of Agriculture

 P. ramorum infested viburnum, Jennifer Parke, Oregon State University

Page D7
Appendix D. Symptoms Associated with P. ramorum

Viburnum

P. ramorum infested viburnum, Oregon Department of Agriculture

P. ramorum infested viburnum leaves, J. Parke, OSU

 P. ramorum infested viburnum

Page D8
Appendix D. Symptoms Associated with P. ramorum

Kalmia

P. ramorum infested Kalmia stems and leaves, Oregon Department of Agriculture

 

Kalmia leaves infested by P. ramorum, DEFRA, UK

Page D9
Appendix D. Symptoms Associated with P. ramorum

Kalmia

Appendix D. Symptoms Associated with P. ramorum

P. ramorum infested Kalmia foliage, J. Fallacy, WSDA

Syringa (Lilac)

P. ramorum infested Lilac foliage, Scottish Agricultural Science Agency

Page D10
Appendix D. Symptoms Associated with P. ramorum

Camphor

 P. ramorum infested camphor tree leaves and green branches, C. Blomquist, CDFA

Loropetalum

P. ramorum infested Loropetalum leaves, C. Blomquist, CDFA

Page D11
Appendix D. Symptoms Associated with P. ramorum

Osmanthus

 P. ramorum infested Osmanthus fragrans, C. Blomquist, CDFA

 O. fragrans leaves, C. Blomquist P. ramorum infested O. heterophyllus, C. Blomquist

Page D12
Appendix D. Symptoms Associated with P. ramorum

Osmanthus

 P. ramorum infested O. heterophyllus plant and leaves, C. Blomquist, CDFA

Conifers

 

Grand Fir, Photo: Santa Clara Dept. of Ag. Douglas Fir, Photo: Dave Rizzo, UCD

Page D13