Tomato – Early Blight on Fruit
Q: I have some beautiful tomato plants this year but something is causing my tomatoes to rot from the stem end. They fall to the ground after the top of the tomato has rotted from the stem. This generally occurs when the color starts to turn. The leaves are turning yellow and dropping. Can you help me remedy the problem?
A: This is a nice example of fruit damage from the tomato disease called early blight. On tomato leaves, the disease starts as a small yellow dot that quickly expands in concentric rings as a “target”. The leaf turns yellow and falls off.
The fungus is present in most soils and can not be eliminated. The best practice to limit the disease occurrence is to mulch under the plant IMMEDIATELY after planting. In this way infected soil can not splash onto lower leaves.
If the disease has just gotten started, spraying upper leaves with a fungicide labeled for garden use like Daconil (click for sources) may be helpful.