It can be very discouraging to have nice big healthy plants with lots of damaged fruit. This is caused by sudden changes in soil moisture, just like this year when we get lots of rain followed by hot dry conditions. Watering regularly and consistently will help prevent this. It can also be caused by a lack of calcium in the soil that can be corrected by using Rot-Stop, which corrects calcium deficiencies and prevents this disease. For other insects and diseases on tomato plants we recommend the Green Light Tomato and Vegetable Spray, which contains neem oil.
Neem oil is an amazing product that is relatively new to the market.
It is not only a safe and effective insecticide, but is also the best fungicide there is for edible plants. It is very safe and works to fight most plant diseases. So if your not sure what's wrong with your plants, use this product and it will prevent most insects and diseases. Another product to keep in mind for tomato plants is Blossom Set, which will pollinate the blossoms so they will set fruit. It will increase the yield on your plants.