Ovulinia azaleae
Ovulinia azaleae is a plant pathogen affecting azaleas and rhododendrons. Ovulinia petal blight Ovulinia petal blight is commonly referred to as Ovulinia flower blight, Azalea flower blight, and Azalea flower spot. First reported in the 1930s on the Belgian-Indica hybrids, petal blight can attack most azaleas under favorable weather conditions. Infected flowers first exhibit small spots, about 1 mm in diameter, which appear water-soaked. The spots enlarge rapidly and become very slimy, causing entire petals to become slimy and limp, usually within 2–3 days after initial infection. Infected areas of flowers soon become tan or light brown, and eventually entire flowers turn prematurely brown. Infected flowers dry and generally cling to the plant longer than uninfected flowers do. One to 20 (commonly two to five) small, black sclerotia (a fungal resting stage) form on an infected flower 6–8 weeks later. They appear first as small white areas on the dried petals and slowly become dark as they mature. Caused by the Ovulinia azaleae fungus, the disease develops during periods of moist weather at flowering time. Early- and late-flowering cultivars or species tend to escape the disease. The fungus overwinters as sclerotia on diseased petals adhering to plants, on the soil