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WSU Puyallup Ornamental Plant Pathology

Symptom Guide: Camellia species

Phytophthora (fy-toff-thor-uh)

Phytophthora species are microscopic organisms that cause disease in many plant species, including Camellia species.

You can learn more about Phytophthora and Sudden Oak Death at the links below.

Camellia species

Prized Garden Plants

Camellia species are beautiful ornamental shrubs and flowering trees that can be found throughout neighborhoods and gardens in the Pacific Northwest.

Diversity

There are more than 250 species of Camellia and many more cultivars and hybrids.

Regulated Species

All species, hybrids and cultivars are regulated as proven hosts for Phytophthora ramorum.

Phytophthora ramorum Symptoms

Leaf Lesions

On Camellia, brown lesions tend to form at the leaf tip and are irregular in shape when the plant is infected with P. ramorum. As with Rhododendron, lesions generally appear along the midrib and petiole. Occasionally lesions form at the edge of the leaf.

The lesions appear diffuse and water-soaked. No fruiting bodies (structures resembling pin-heads or molds) are visible.

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Lesions from P. ramorum infection on Camellia sinensis leaves.

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Defoliation

Defoliation often occurs on lower leaves of infected Camellia plants. No canker or dieback symptoms have been observed on Camellia.

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P. ramorum on Camellia (C. japonica) leaves. Lower leaves in photo also have some fungal symptoms with pinhead-like fruiting bodies.

Sunscald

Camellia foliage can be affected by sunscald. Lesions from sunscald have defined margins, are not water-soaked, and are not associated with the midrib. These lesions can become infected with opportunistic fungi such as Pestalotia and Pestalotiaopsis.

Sunscald injury on Camellia leaves

More Resources

Learn more about Sudden Oak Death

More information, including links to youtube videos, about Sudden Oak Death is available here. You can also find information for specific audiences (e.g. nursery professionals, garden managers, master gardeners, etc.) on our Sudden Oak Death Education Program webpage.

View more online symptom guides

There are many additional photos of symptoms on Camellia species in the other guides we have provided here. Viewing multiple photos of symptoms on Camellia species may help you determine if Phytophthora ramorum is involved.

Management

Visit our webpage for Nursery Productions if you are looking for Best Management Practices for managing Phytophthora ramorum. These practices are also useful for managing other Phytophthora diseases, such as those that cause root disease, which can be more damaging than P. ramorum on their hosts.

Plant Disease Diagnostics

Guidelines for submitting a sample

Visit our Sample Submissions Guidelines webpage for information to help determine whether it will be helpful to submit a plant sample for professional diagnostics.

WSU Plant and Insect Diagnostic Laboratory

The WSU Plant Clinic can provide diagnostic services to identify the cause of symptoms on Rhododendrons and other plant species.

Click here to read their instructions for submitting a sample.

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