Answer: The white film on the leaves is probably powdery mildew. It's a fungal disease and you can stop the spread by removing affected leaves as soon as you notice the problem. To avoid, make sure there's plenty of air circulation around your plants and provide full sunshine (partial afternoon shade if your summer weather is really hot). Overwatering can cause root rot which results in wilting. If you've improved the drainage your plants may recover and begin putting out healthy new growth. Sounds like you've dusted with Sevin, which is an insecticide, not a fungicide. I'd avoid using such a powerful insecticide on flowering plants; it's toxic to bees and bees can't resist visiting brightly colored flowers. They can pick up residue and take it back to their nests. Hope your gerbera daisies regain their health.
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