Disease and Fungus on African Violets

Botrytis Blight

• The fungus Botrytis cinerea is responsible for this blight disease. Initial symptoms include lesions occurring on the leaf's underside that are small and water-soaked. Often, there's a fuzzy coating on the leaf, which eventually turns dark brown to gray. The flowers also show similar signs of blight damage. High relative humidity and poor air circulation contribute to the well-being of this fungus. Preventive measures include spacing the plants apart enough so that leaves from other violets do not come in contact with other plants. This fungus spreads by direct contact with a diseased leaf.

Crown or Root Rot

• The fungus Pythium ultimum is the cause of crown and root rot, and is generally attributed to over-watering. This fungus infects plants in any stage of growth and causes the leaves to wilt and the crown of the plant and associated roots to become soft, mushy and dark in color. To prevent this disease, use a pasteurized soil mixture and ensure the container allows for proper drainage. This is a general rule of thumb for most fungal diseases, as they require moist conditions to grow and spread.

Powdery Mildew

• Mildew grows in moist, cool climates with poor air circulation. Symptoms include a powdery substance that is light gray in color and shows up on the petioles and stems of the African violet. Powdery mildew reduces the bloom lifespan of an African violet and compromises the entire plant. To prevent this mildew from forming, maintain the violet in a container with good drainage properties and ensure there is an adequate amount of air circulating around the plant.

Petiole Rot

• Petiole rot commonly occurs where the the plant stems or leaves come in contact with the pot. The fungus is aggravated by salt accumulation on the rim of the pot. Keep the rim of the pot clean -- or cover it with tinfoil to prevent rot. Salt can also be removed from the soil by heavy watering that flushes soluble salts through the pot and out of the soil.