Powdery mildew of plane tree

The causal agent of this plant disease is the fungus Erysiphe platani. It is a strictly parasitic organism that specializes in infecting the foliage and tender shoots of trees belonging to the Platanus genus, causing visible surface growth.

The primary hosts of this pathogen are various plane tree species, including the London plane tree (Platanus × acerifolia). The fungus primarily attacks developing tissues during the spring and summer growth flushes, thriving in humid environments.

Clinical signs include the appearance of a powdery white or gray mycelial film on both sides of the leaves, petioles, and soft stems. As the infection progresses, the leaves may become distorted, curled, and brittle, often leading to chlorosis and premature defoliation.

The development of the fungus is accelerated by high humidity levels and lack of sufficient air movement within the tree canopy. Spores are primarily wind-dispersed, allowing the pathogen to spread rapidly across urban landscapes and nurseries during the growing season.

• Sanitation through the removal and destruction of fallen leaves and infected twigs.
• Pruning to increase light penetration and air circulation within the canopy.
• Application of approved fungicides during the early stages of infestation.
• Selection of resistant cultivars if available for new plantings.

The economic and aesthetic impact of Erysiphe platani is significant, as it severely stresses the tree by impairing photosynthesis and diverting vital resources to combat the infection. Chronic infestations lead to stunted growth and increased susceptibility to other environmental stressors and secondary pathogens.