Potato wart

Potato wart manifests as fleshy growths on tubers and stolons, which resemble cauliflower inflorescences in appearance. Initially, they are light in color, but as they develop, they darken, rot, and turn into a foul-smelling slimy mass. On stems, leaves, and flowers, the pathogen causes the appearance of green growths; atypical forms of damage, such as leaf crinkling or nodular deformations, are also encountered.

The development of the disease is closely related to soil moisture and temperature, with high humidity (60–80%) and temperatures of +15…+18°C being the most favorable conditions. The pathogen infects potatoes best in light and acidic soils, and the risk of infection increases critically with prolonged continuous cultivation of the crop on the same plot. The parasite's resting spores remain viable in the soil for up to 30 years.

The resistance of potato varieties to potato wart is based on a hypersensitivity mechanism, in which plant cells at the site of zoospore penetration die immediately, isolating the infection site and preventing further development of the fungus. Assessment of resistance is a mandatory stage of state variety testing. Cultivating resistant varieties in the infested zone contributes to the gradual clearing of the soil from infection, as the absence of a susceptible host interrupts the parasite's development cycle.