Geraniums (Pelargonium spp.) are shrub-like perennials that bloom in a range of colors including coral, purple, pink or red. The wavy or lobed foliage is dark green, often with yellow edges or markings depending on variety. A fungal disease causes brown leaves on the plants.
Botrytis blight is a potential fungal disease in geraniums caused by Botrytis cinerea. Left uncontrolled, the disease rots and kills the entire plant. The fungus infects and starts from any area of plant.
The disease starts with the appearance of gray, fuzzy lesions or spots on foliage. The lesions enlarge to cover larger areas as disease progress. Leaves start to turn brown and die. The lesions are often V-shaped and display concentric rings. The fungus gradually spreads to flowers and stems. Flowers brown and die early.
Keep plants clear of weeds and debris and use well-drained soil. Obtain disease-free plants from reliable sources. Avoid watering plants during late afternoons or evening. Recommended chemical control options include chlorothalonil, neem oil or potassium bicarbonate.