Geraniums (Pelargonium spp.) are shrub like perennials with round, wavy foliage and single or clustered flowers in shades of coral, red, purple, white and pink. The plants thrive in warm weather and well-drained soil. A fungal infection causes spots to appear on geraniums.
Geraniums are susceptible to botrytis blight caused by Botrytis cinerea. The disease can infect plants during at any stage of growth. The fungal growth is favored by heavy moisture and high humidity.
Botrytis blight is characterized by the appearance of distinct spots or lesions on foliage and flowers. The spots have concentric rings and are sometimes V-shaped. Spots gradually grow in size to form large patches that eventually rot the entire plant. Flowers brown entirely and drop. During advanced stages of disease, infected plant areas develop gray, fuzzy growth.
Keep plant free from weeds and debris. Grow geraniums in well-drained soil. Obtain disease free plants from reliable sources. Do not use overhead irrigation methods. Chemical control options include the use of chlorothalonil, potassium bicarbonate or Bacillus subitlis.