Pink disease

Pink disease, caused by the fungus Erastia salmonicolor (syn. Corticium salmonicolor), is a serious phytopathological condition affecting a wide variety of woody plants. This basidiomycete fungus primarily attacks the bark and cambium layers of tree stems and branches, often leading to canopy dieback or the total death of the host plant if left untreated.

The host range of Erastia salmonicolor is extensive, impacting both industrial and fruit-bearing tree species. Key susceptible crops include rubber (Hevea), coffee, cocoa, citrus, eucalyptus, and various temperate fruit trees. The disease is most devastating in tropical and humid subtropical environments where climatic conditions facilitate rapid pathogen growth.

Diagnosis of the disease typically relies on the visual appearance of the fungal growth on the bark. The symptoms progress through several distinct stages:

• Initial emergence of thin, white, cobweb-like mycelial strands.
• Development of a characteristic pink or salmon-colored encrustation.
• Deep longitudinal cracking of the bark and cambium decay.
• Yellowing and wilting of foliage on affected branches.

Environmental conditions are the primary drivers of disease spread. High relative humidity, warm temperatures, and frequent rainfall provide the necessary moisture for spore germination and mycelial spread. The pathogen is easily disseminated by wind-blown spores and rain splashes, particularly exploiting fresh pruning wounds, natural cracks in the bark, or insect-caused injuries.

Management strategies focus on a combination of cultural practices and chemical control. Pruning and destroying infected branches during the dry season is crucial for reducing inoculum pressure. Improving orchard ventilation through proper tree spacing helps lower humidity around the canopy. Additionally, the application of copper-based fungicides serves as an effective barrier to protect healthy tissues from infection.