Viola odorata and Viola tricolor
Leaf Spots (fungi – Alternaria violae, Cercospora violae): Chlorotic spots on lower leaves, centers later turn brown. Usually on lower leaves first. Regular sprays with a foliar fungicide will control the disease.
Anthracnose (fungus – Colletotrichum violae – tricoloris): Browning or blotching of leaves. Spots may be small at first, but later enlarge. Spots may coalesce. Sunken, elongated dark brown to black lesions may appear on stems. In severe cases entire plant may be killed. Regular foliar fungicide applications will control this disease.
Scab (fungus – Sphaceloma violae): Small, green water-soaked dots. These later enlarge to form circular scabby spots. They may be gray-to-white surrounded by a dark-green border. Lesions may extend along a leaf veins and cause the veins to become distorted. Wilting of the leaves may result from petiole infections. A regular spray schedule with a foliar fungicide
Damping-Off (fungi – Rhizoctonia spp., Pythium spp., and Fusarium spp.): Plants wilt and die suddenly. A dark sunken area may be seen on the stem at or near the soil line. Use sterilized potting soil. Remove and destroy diseased plants.
Cotton Root Rot: (See the section on Cotton Root Rot)
Southern Blight: (See the section on Southern Blight)