Dogwood powdery mildew

The causal agent of this disease is Erysiphe pulchra, an ascomycete fungus. It functions as an obligate biotroph, meaning it relies entirely on the living tissues of the host plant to derive nutrition, which significantly weakens the physiological status of the affected dogwood trees.

This pathogen specifically affects various species of dogwood, most notably Cornus florida. The impact is significant in both landscape horticulture and commercial nurseries, as the disease can render plants unsellable and severely impair the growth of young specimens.

Symptoms typically manifest as white, powdery fungal colonies on the leaves. As the infection progresses, the foliage often shows symptoms of chlorosis, necrosis, and curling. Severe infestations lead to the distortion of young shoots and the stunting of flower buds, negatively impacting the tree's overall structure.

The development of Erysiphe pulchra is favored by warm days and cool nights, coupled with high humidity or poor air circulation within the canopy. These environmental conditions are ideal for the rapid production and wind dissemination of conidia, which spread the infection throughout the garden.

Integrated pest management (IPM) is essential for controlling this disease. Key strategies include:

• Selection of resistant cultivars;
• Pruning to improve light penetration and air movement;
• Application of specialized fungicides such as sulfur-based products or systemic triazoles.