Tomato Diseases - Fruit
ANTHRACNOSEAnthracnose is a very common fungus that causes tomato fruit to rot. Symptoms: Small, round, sunken spots appear on the fruit. The spots will increase in size and darken in the center. Several spots may merge as they enlarge. The fungus is often splashed onto the fruit from the soil. It can also take hold on Early Blight spots or dying leaves. Wet weather encourages the development of Anthracnose. Overripe tomatoes that come in contact with wet soil are especially susceptible. Management: Copper sprays offer some resistance. Remove the lower 12" of leaves, to avoid contact with the soil. Don't water the leaves, just the base of the plant. More info and photo from Cornell University Cooperative Extension
BACTERIAL SPECKThere are several bacterial problems that affect tomatoes including Bacterial Speck. Symptoms: Tiny, raised, dark spots, usually with a white border. Management: Copper fungicide at first signs of symptoms. More info and photo from Texas Cooperative Extension
BLOSSOM END ROTBlossom End Rot is as good a description as any. Symptoms: Dark brown/black spots develop at the blossom end of the fruit and enlarge as the fruit rots. Management: Generally attributed to a lack of calcium during fruit set. This could be caused by too much high nitrogen fertilizer or uneven watering, resulting in fluctuations of nutrient availability. Management: Remove affected fruit and provide regular, deep waterings. More info and photo
BUCKEYE ROTBuckeye Rot is more common in Southern states, especially during wet periods. Symptoms: Buckeye Rot is similar to Blossom End Rot, except on green fruit. On ripened fruit the rotting area will appear water soaked, but not dark in color. The rot develops on the area of the fruit that touches the soil. The spot will enlarge and develop concentric rings that resemble a buckeye. The affected area is smooth, distinguishing it from Late Blight, which has a rough surface. Management: Remove affected fruit and keep future fruits from contact with the soil. More info and photo from Virginia Cooperative Extension
GRAY WALLGray Wall is essentially a ripening problem. Symptoms: The green fruits may have a gray cast or gray blotches. Ripe fruit will have green or brown areas on the inside of the fruit. Management: Good growing conditions will prevent gray wall. Make sure plants aren't heavily shaded, are receiving even waterings and fertilizer and that the soil is not compacted around the roots. Cool temperatures and stressed or unhealthy plants also contribute to the problem.More info and photo from Cornell University Cooperative Extension
Read more about tomato diseases that affect the leaves.