African violets with crown and root rot have the symptoms or drooping leaves around the outside of the plant. The smaller inside leaves appear stunted, eventually turning black and shriveling. Causes of this fungal disease include over-watering, poor container drainage or a crown planted too deeply so moisture builds around the crown and root system. There is no treatment for this leaf problem. Prevent infecting other African violets by disinfecting the container with a water and bleach solution.
Botrytis blight in African violets is a fungal disease that causes the leaves to appear blighted. The symptoms of this leaf problem are dark brown or gray colored leaves with a fuzzy coating. Treat an African violet with Botrytis blight by removing all dead and infected leaves and move the plant to an area with good air circulation. Botrytis blight often happens after a problem with mites, so it is important to control this pest to prevent future leaf problems.
African violets with mealybugs have stunted and distorted leaves throughout the plant. Mealybugs are small, 1/4-inch long bugs with white, soft bodies covered in a waxy substance. The bugs feed on the top and bottom of leaves by sucking sap from the plant. A symptom of a mealybug infestation is a sticky honeydew substance on the leaves. Treat a mealybug leaf problem by applying insecticidal soap spray or botanical pyrethins spray on the top and bottom-side of the leaves according to the application instructions on the bottle. Prevent introducing mealybugs to other plants by inspecting the top and bottom side of leaves for all new plants that come into the home.
A common leaf problem in African violets is water spots on the leaves. Splashing cold water on the plant leaves creates a white or yellow ring where the water falls. This leaf problem is not lethal, but creates an unsightly appearance. Prevent this leaf problem by wiping the leaves after watering. Applying water by setting the container in a tray of water allows the plant to pull water into the container without touching the leaves.