Plant Pathology: Extension: Plant Disease Library

Camellia Canker and Die-back

Canker and die-back, caused by the fungus Glomerella cingulata, is potentially one of the most serious diseases of both japonica and sasanqua camellias. Plants weakened by transplanting shock, poor soil drainage, improper nutrition, drought, or other stress factors are more susceptible to infection, but the disease is not limited to weakened plants.

Camellia varieties differ in their susceptibility to this disease. Select cultivars having a high degree of resistance. ‘Governor Moulton’, ‘Professor Sargent’, ‘Rose Emery’, and ‘Woodville Red’ cultivars of C. japonica are somewhat resistant, as are the C. sasanqua cultivars, ‘Daydream’ and ‘Setsugeka’. Avoid stressing and wounding camellias. Plant camellias in well-drained soils and provide adequate fertilization and irrigation to keep plants healthy. Avoid excessive nitrogen fertilization and mulch plants to protect the root system from water and temperature fluctuations and to reduce weeds.

The fungus needs a wound or opening to enter into the plant. Natural leaf scars and lenticels are probably the most common entry point. However, injury by mowers, rodents, yard tools, grafting, etc., create wounds where infection may occur. Warm (65-85° F), wet weather and high nitrogen fertilization favors disease development.

Canker and die-back may occur on plants of any age. The first symptom is sudden wilting of leaves on young twigs. As the leaves wilt, they turn dull green and then brown while remaining attached to the stems. Cankers, which often girdle the branch or twig, form on infected branches. Cankers on larger branches may persist as elliptical, slightly sunken lesions. The bark and wood of the affected branches turns dark brown. If infection occurs through wounds on limbs or at the base of the plant, large limbs or the whole plant may wilt. Pinkish orange pustules or spore masses may be seen around the cankers or on infected twigs during extended periods of wet weather. Spores (conidia) are spread by splashing water.

Prune and burn or discard disease branches and twigs when die-back occurs. Prune four inches below the infected area into healthy tissue. Make cuts just above vigorous side branches. Always disinfect pruning tools after each cut by wiping blades with rubbing alcohol or dipping them into a 10% bleach solution (1 part bleach in 9 parts water). Afterwards, rinse tools with fresh water and apply oil to prevent corrosion and discoloration of metal parts. Fungicide applications to pruning cuts and wounds may reduce potential infection and disease spread. Consult the Georgia Pest Control Handbook for fungicide recommendations.

Jean L. Williams-Woodward, UGA Extension Plant Pathologist - Ornamentals
E-mail any questions or remarks to Jean L. Williams-Woodward