|My roma tomato plant is wilting and has white spots on the leaves. We were able to get a few good tomatoes out of the plant. Any ideas on what it may be. How can I save it?|
|It sounds like powdery mildew. Powdery mildew is unique among plant diseases in that it doesn't require a wet leaf surface to spread. It can thus thrive during hot, dry weather. The first line of defense is to grow resistant varieties. Next, remember that while the disease is unsightly, it doesn't cause any real harm to many of its victims (though it will damage some plants.)
Here are some general rules for helping control fungal diseases. Start by making sure that your plants are getting enough direct sunlight. (Eight to ten hours a day is generally the minimum for plants that flower or bear fruit.)
You'll also want to make sure that there's enough room between plants for air to circulate freely. Overcrowding not only makes plants more susceptible to diseases, if leaves touch other plants, those diseases can easily be spread. The general advice to inhibit the spread of fungal diseases is to avoid wetting leaf surfaces. In the case of powdery mildew, you can actually inhibit infection with periodic strong sprays of water (not so strong as to damage the plant.) Remove affected leaves. If plants seem infested with powdery mildew, it's best to pull them out and dispose of in the trash, so it doesn't spread, and also clean up any of its leaf litter.
Tomato pollen isn't viable much over 90 degrees, so fruits won't set. What have your temperatures been? Another possibility is that the flowers aren't being pollinated at all. Try gently tapping and shaking your plants in the early morning to see if you can get some fruit to set.