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How to Manage Pests
UC Pest Management Guidelines
Floriculture and Ornamental Nurseries
Camellia (Camellia spp.)
Disease Control Outlines
(Reviewed 1/02,
updated 1/02)
In this Guideline:
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| Disease (causal agent) | Symptoms |
Survival of pathogen and effect of environment |
Comments on control |
Dieback
(Glomerella cingulata) |
Wilting and dying of branches. Leaves darken and often remain
attached. Branch is girdled by fungus that enters through injuries, including
leaf scars. |
Found in warmer areas of California. Favored by wet, warm
conditions, weakened plants, and injuries. Fungus spores (conidia) are spread
by splashing water. Fungus has a wide host range. |
Prune diseased tissues and protect wounds with a fungicide such
as captan. Avoid overwatering. |
Flower blight
(Ciborinia camelliae) |
Flowers have dry rot with accented veins. Only petal tissues
are infected. First symptoms are small tan or brown necrotic spots in the
center of the flower that enlarge and move rapidly to the base of flower.
Rotted flowers are heavy and easily fall to ground. The fungus continues to
develop, forming a sclerotia in the calyxes of infected flowers. |
Sclerotia survive on or in soil and germinate for several years
producing fruiting bodies (apothecia) that discharge spores (ascospores)
forcibly into the air. |
Where practical, pick up all blossoms because fallen blossoms
either may be infected or may become infected while on the ground. Prevent
sclerotia from germinating by spraying ground with PCNB annually.
Thiophanate-methyl will protect petals from infection but sprays must be
applied frequently as new flowers open. Mulches 4 inches or more deep will help
prevent apothecia from reaching the surface. |
Gray mold
(Botrytis cinerea) |
Necrotic, brown spots. Rot does not move to the base of the
flower as rapidly as the flower blight fungus. Woolly gray fungus spores form
on decayed blossoms under high humidity. |
Favored by cool wet weather. Spores are airborne. Fungus
survives on and in old flowers. |
Avoid overhead irrigation. Clean up plant debris, especially
floral tissues. Protect flowers with a fungicide effective against Botrytis
such as fenhexamid. more info |
Phytophthora root rot
(Phytophthora spp.) |
Plants stunted and low in vigor. Foliage yellows, plant wilts
and dies. Roots rotted. When plants collapse, the stem is girdled at or below
the soil line. Phythopthora cinnamoni is often involved but other
species also infect camellias. |
Phytophthora spp. survive in soil as resting spores.
They are common in stream and ditch water. Infective spores (zoospores) swim
very short distances in soil water. Disease is favored by poor drainage, long
wet periods, and standing water. |
Heat or chemically treat propagation and growing media. Drench
plants on a preventative basis with mefenoxam. more
info |
Camellias are also susceptible to several viruses
and viroids such as color break virus and golden ring spot complex.
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UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Diseases
R. D. Raabe (emeritus), Environmental Science, Policy, and Management (ESPM),
UC Berkeley
M. E. Grebus, Plant Pathology, UC Riverside
C. A. Wilen, UC IPM Program, UC Cooperative Extension, San Diego Co.
A. H. McCain (emeritus), Environmental Science, Policy, and Management (ESPM),
UC Berkeley
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