Pink disease

Pink disease, caused by the fungus Necator salmonicolor (syn. Corticium salmonicolor), is a destructive plant disease primarily affecting woody plants. The pathogen colonizes the bark and cambium, leading to necrosis and eventually girdling the branches or trunks, which blocks the flow of nutrients and moisture, causing localized or total plant death.

The host range of this fungus is extensive, especially in tropical and subtropical regions. It affects a variety of economically important crops such as rubber trees, cocoa, coffee, and citrus, as well as numerous ornamental species. The fungus is highly opportunistic, often entering the plant through bark cracks, pruning wounds, or existing lesions caused by environmental stress.

The primary symptom of the disease is the emergence of a conspicuous pink or white powdery mass of fungal mycelium on the surface of branches or stems. As the infection progresses, the bark becomes brittle, starts to crack, and peels away. Foliage on the affected branches typically yellows and wilts, and in severe cases, the infected limb may break off due to structural decay.

Environmental conditions are the main drivers of disease spread. Necator salmonicolor thrives in high-humidity environments with frequent rainfall and warm temperatures, which facilitate the production and dispersal of spores via water splash and wind currents. Dense canopy architecture that restricts airflow creates an ideal microclimate for the pathogen to establish itself.

Effective management strategies include the following:

• Rigorous sanitation, involving the prompt pruning and burning of all infected branches.
• Scraping off infected bark areas and applying copper-based wound dressings to prevent reinfection.
• Improving orchard hygiene by maintaining proper tree spacing and thinning the canopy to reduce humidity.
• Applying preventive fungicide sprays, particularly before the onset of the wet season, to protect vulnerable tissue.