Diseases

Tomato Early Blight

Solanum lycopersicum L. var. lycopersicum

A fungal disease of tomatoes caused by Alternaria solani, characterized by the appearance of dry spots with concentric zoning. It affects all above-ground plant organs, including fruit, and can lead to stem death.

In the reference 9 varieties crop Tomato, where this is mentioned in the description.

The primary causal agent of tomato early blight is the fungus Alternaria solani Sorauer, though the roles of Alternaria alternata and Alternaria tomatophila are also noted. The disease affects all above-ground organs, manifesting as round, dark-brown spots with characteristic concentric zoning in a target-like pattern. Under high humidity, a velvety black coating of sporulation forms on the spots, and affected tissues eventually dry out and crack.

Stem infection often manifests as elongated spots capable of causing breakage and plant death, while on the fruit, the disease localizes near the peduncle as depressed dark zones. Although no classical races have been identified for the pathogen, there is significant intraspecific variability in the aggressiveness of isolates. In breeding, resistance to Alternaria solani is encoded by the designation As, and resistance to Alternaria stem canker, caused by Alternaria alternata f. sp. lycopersici, by the code Aal.

General information about the subject — on the page Alternaria blight.

Sources8

Varieties of Tomato mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.