Beat the heat – with an early start. Make the most of cool mornings. Do yardwork early in the day. Keep yourself hydrated; drink water.
The rot starts out as a brown spot on the flower end of the fruit. As the fruit grows, the spot becomes a tough black or brown lesion. (The rest of the fruit is still edible.) The cure? Keep soil moisture as even as possible – not easy during heat waves. While fruiting, mature tomato plants need about 1 gallon of water per day. If you use a drip irrigation system, tomatoes can get by on 5 gallons a week and still produce abundant fruit. Remember: The secret is consistency.