Diseases

Tomato Late Blight

Solanum lycopersicum L. var. lycopersicum

A fungal disease of tomato caused by the oomycete Phytophthora infestans. It affects all plant organs, forming necrotic spots and a specific mold, and is regulated by resistance genes Ph-1, Ph-2, and Ph-3.

In the reference 17 varieties crop Tomato, where this is mentioned in the description.

The pathogen of the disease is the oomycete Phytophthora infestans, in the populations of which races with varying virulence to tomato are distinguished, in particular T0, T1, and T2. The interaction between the pathogen and the plant follows the 'gene-for-gene' principle, where races T1 and T2 are capable of overcoming resistance conferred by the Ph-1 and Ph-2 genes.

Symptoms manifest as watery spots on leaves, stems, and fruits, which become covered with a characteristic whitish sporulation mold when humidity exceeds 75%. Subcutaneous brown spots appear on the fruits, leading to subsequent softening of the tissues.

Breeding for resistance relies on genes introgressed from wild tomato species, among which Ph-3 is considered the most effective. In the international classification of varieties, resistance to the pathogen is designated by the code Pi.

General information about the subject — on the page Late 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.