Then cool and dry. Older seeds are more easily injured by this treatment. Use recommended protectant fungicide. Whitish powdery growth on leaves and stems. Leaves die from base of plant.
Affected plant lose vigor and cease growth.
Spray with recommended fungicide as soon as mildew appears. Small, roundish spots with gray or whitish centers. Several spots may run together, killing the entire leaf. Spray with recommended fungicides two or three times during the season. Many virus diseases affect zinnias.