Camelia Petal blight is a fungal disease. Flowers rapidly become brown, heavy with water, discolored and rotten. Individual flower veins become darker than their surroundings. Fungal spores may survive five years in the soil and are spread by wind.
Other conditions may look like petal blight. These include buds that dry out and drop and flowers that turn brown and sticky especially at the tips. These conditions are usually cultural or varietal. Adverse cultural conditions include overhead water, weather extremes, too much or too little water, or too much sun.
Sasanqua Camelias do not get Petal Blight. Non chemical control is cultural. Good housekeeping is essential. Pick all infected flowers off. Rake up all decayed blossoms and leaves. Discard (do not compost.) Replace with fresh mulch. Chemical controls include Green Light Fung-Away and Bayer Disease Control. Apply according to package directions throughout the bloom season. It is very important to begin spraying buds as they begin to develop and open.