Cause Saprophytic fungi that live on the excrement of cottony camellia scale and soft brown scale, common camellia insect pests. The fungus Atichia glomerulosa (sexual Seuratia millardetii) called false sooty mold has been found in Washington. This fungus lacks hyphae, is not parasitic and does not seem to be associated with scale insects. Sooty mold typically causes little damage to plants aside from an aesthetic problem. Very heavy fungal coverings on leaves may interfere with photosynthesis and cause some plant decline.
Symptoms Dark, brown-black, powdery fungus growth over leaf surfaces. Severe black fungal growth will almost completely cover the upper leaf surface. Black fungal growth may cover anything that the excrement falls on including other plants and even the walls or windows of an adjacent house.
Cultural control
- Control the scale insects. Consult the PNW Insect Management Handbook.
- If desired, hand wipe leaves to remove extremely heavy coverings of sooty mold.
- Wash honeydew from plants with a strong stream of water. Choose a time when leaves will dry quickly.
Reference Gills, I.M. and Glawe, D.A. 2008. Characterization of Seuratia millardetii on Camellia species and in artificial culture. North American Fungi 3:215-229.