|Botrytis Blight||Petals turn brown and fall. Leaf spots form, especially where faded petals have fallen. Flower buds are killed before opening.||Botrytis cinerea||Space plants to insure good air circulation. Maintain low humidity. Avoid watering late in the day. Remove crop debris. Apply a fungicide to protect plants.
|Cercospora Leaf Spot||Tan spots with reddish-brown halos develop on leaves.||Cercospora||Water in a manner that keeps moisture off the leaves. Apply a fungicide to protect plants.|
|Powdery Mildew||Yellow areas form on leaves. These may become purplish. White, cottony fungal growth forms on the lower surface of the leaf.||Erysiphe polygoni||Apply a fungicide as soon as any mildew is observed.
|Virescence||Flowers are green and may be stunted. Leafy shoots grow from the flower parts. Plants decline and die.||Phytoplasma||Discard infected plants. Maintain good insect control.|
|Viruses||Leaves may be mottled, have yellow spotting, dead flecks, line or ringspot patterns. Plants may be distorted or have flower color breaking, or few flowers.||Hydrangea ringspot, tomato ringspot, impatiens necrotic spot||Plant virus-indexed cuttings. Maintain good insect and mite control. Destroy infected plants.|
Cercospora leaf spot.
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