How can I effectively prevent and treat mildew on tomato plants?

To prevent and treat mildew on tomato plants, you can:

1. Ensure good air circulation around the plants by spacing them properly.
2. Water the plants at the base to avoid wetting the leaves.
3. Apply fungicides labeled for mildew prevention.
4. Remove and destroy any infected leaves or plants.
5. Consider planting mildew-resistant tomato varieties.