Flower and Petal Blight
Ciborinia camelliae
2 host plants · Fungal
Last updated
Brown spots appear on camellia petals, eventually covering entire flowers as they wilt and drop. Ciborinia camelliae thrives in wet conditions with cool temperatures. You'll see the fungus overwinter in spent flowers on the ground. Remove fallen blooms thoroughly, rake debris, bury or compost plant material properly, and consider resistant sasanqua cultivars for fall flowering.
Try several methods over a few seasons. Carefully remove and destroy any diseased camellia flowers. Remove affected tissue promptly, cutting into healthy wood. Improve air circulation by thinning dense growth and avoid overhead watering during susceptible periods. Preventive fungicide applications may help where the problem recurs annually.
Quick Reference
Management
Bloom period through petal fall. Wet spring weather increases severity.
Cool wet conditions on flowers (10-20°C / 50-68°F); rain on bloom critical; Botrytis and Ciborinia both favor high humidity.
Cultural Controls
- Try several methods over a few seasons.
- Carefully remove and destroy any diseased camellia flowers.
- Rake and destroy old leaves, flowers, and other plant debris, especially under the camellias.
- Even spent flowers up in the canopy must be removed.
- Do not put on compost heap unless they are buried.
- Carefully remove the top 3 to 4 inches of soil from beneath plants to eliminate sclerotia in heavily infested soil.
Flower and petal blight is common in areas west of the Cascade Range, where wet springs coincide with camellia and rhododendron flowering season.