Alternaria leaf spot of hyacinth

Pathogen and disease type. The leaf spot disease of hyacinths is caused by the fungus Alternaria hyacinthi. As a pathogenic fungus, it primarily acts as a foliar parasite that disrupts the photosynthesis of the plant, potentially leading to weakened bulb development and reduced vitality during the subsequent growing season.

Host plants. The primary host for this pathogen is the common hyacinth (Hyacinthus orientalis). The fungus is known to attack both the foliage and the flower stems. In some cases, if environmental conditions permit, the infection can persist on the bulbs themselves, particularly if they are stored in damp conditions.

Symptoms and signs. The infection manifests as small, water-soaked spots on the leaves, which later enlarge and turn dark brown or black. Under high humidity, a velvety olive-black fungal growth becomes visible on the surface of these necrotic lesions. Eventually, severe infections cause the leaves to wilt, turn yellow, and die prematurely.

Conditions for development. Alternaria hyacinthi thrives in warm, humid conditions with frequent rainfall or heavy dew. The fungus overwinters in infested plant debris in the soil or on infected bulbs. Spores are easily disseminated by wind, rain splashes, and gardening tools, making rapid spread possible in dense and poorly ventilated plantings.

Harmfulness and control. The disease causes significant aesthetic damage and hinders the plant's ability to store energy in the bulb for the next flowering cycle.

• Use disease-free, high-quality bulbs for planting.
• Remove and destroy all infected plant material during and after the season.
• Ensure adequate spacing between plants to improve airflow.
• Apply preventative fungicides when weather conditions favor disease development.
• Maintain low humidity and good ventilation in bulb storage areas.