Platanus leaf spot

Platanus leaf spot is caused by the fungus Pseudocercospora platanigena, which acts as a serious pathogen for various species of the Platanus genus. This fungal disease specifically targets the foliage, leading to necrosis of leaf tissues and impacting the overall vigor of the tree. It is considered one of the common leaf-spotting diseases in urban environments.

The primary symptom of this infection is the appearance of small to medium-sized spots on the leaves. These spots are often dark brown or black, occasionally irregular in shape, and may exhibit a lighter halo. When humidity is high, a distinct grayish or olive-colored fungal growth can be observed on the underside of the infected leaves, indicating active sporulation.

The pathogen thrives under conditions of high humidity and moderate temperatures. The fungus overwinters primarily in leaf debris on the ground. When environmental conditions improve in the spring, the spores are disseminated through wind and water splashes, landing on healthy foliage to initiate a new cycle of infection.

The damage caused by Pseudocercospora platanigena results in premature defoliation, which severely hampers the tree's photosynthetic capability. Repeated infections year after year can weaken the tree, making it susceptible to other pests and diseases, and significantly reducing the aesthetic value of urban landscape plantings.

Management and prevention strategies are essential for maintaining healthy trees. Key actions include:

• Rigorous sanitation: collecting and destroying fallen leaves to remove the overwintering source.
• Improving air circulation through proper pruning of the tree crown.
• Applying preventive fungicide treatments at the first sign of bud break.
• Utilizing copper-based or systemic fungicides during wet spring periods.