Review of literature on camellia flower blight caused by Ciborinia camelliae

Abstract

Ciborinia camelliae Kohn is the most destructive pest or disease problem of camellias (Camellia spp.) The pathogen is related to common and widespread plant pathogens in the genera Sclerotinia and Botrytinia (anamorph=Botrytis). Sclerotia form in infected petals and remain dormant in plant debris until the next season. In early spring, apothecia are produced from the sclerotia and release windborne ascospores. Infection causes the petals to turn brown and the flowers to fall prematurely. The disease has been identified in Japan (1919), the United States (1938), New Zealand (1993), and parts of Europe (1999). It has now spread over the lower North Island and upper South Island of New Zealand, with isolated outbreaks in Christchurch and Auckland. Control of this disease has proved difficult even though: (1) only camellia flowers are infected, (2) there is no secondary infection, and (3) ascospores are present for only 2–3 months each year. To date, fungicides have given less than satisfactory control of the disease and possible control measures are reviewed. Interest in potential biocontrol agents is growing but remains an unexplored alternative. Resistant varieties offer the best management option for the future.