Ovulinia

Ovulinia is a specific fungal disease caused by the pathogen Ovulinia azaleae. This microscopic fungus primarily attacks ornamental shrubs of the Ericaceae family, causing a condition widely known as "azalea petal blight." The disease is localized and affects only the reproductive organs of the plant.

The primary hosts of the pathogen are species of the genus Rhododendron, including azaleas. The disease targets only the flower petals. Under conditions of high humidity, the fungus develops rapidly, turning vibrant inflorescences into slimy, brown masses, which completely destroys the plant's aesthetic value during its peak blooming period.

Symptoms of infection appear as small spots on the petals that quickly enlarge and merge. The affected areas become soft and water-soaked. A characteristic diagnostic feature is the formation of black sclerotia on the surface of infected petals; these are dense structures that allow the fungus to overwinter in the soil beneath the shrub.

The development of Ovulinia is favored by long periods of high humidity, fog, and frequent rainfall during the flowering season. The optimal temperature for spore germination is between +15°C and +20°C. The infection spreads via rain splashes and wind currents that carry spores to neighboring flowers and healthy bushes, leading to outbreaks in dense plantings.

To protect plants, a combination of measures is used: sanitary pruning and disposal of infected flowers, collection of fallen petals, and soil treatment with fungicides to suppress overwintering sclerotia. Prevention includes choosing resistant cultivars, ensuring good air circulation within the canopy, and avoiding overhead irrigation on the flowers.

• Collection and disposal of infected plant debris.
• Mulching the soil with fresh bark to isolate spores.
• Application of systemic fungicides (benzimidazoles, triazoles).
• Management of humidity levels during the flowering period.