Sori locular, 1-4 mm, in galls on stems, stolons and tubers. Sporiferous hyphae lining locules, producing spore balls to interior. Immature locules surrounded by brown corky tissue of potato [ Solanum tuberosum ].
Although malformed tubers are conspicuous (see Symptoms) and the spore sori are distinctive, there is no reliable inspection method to detect spores of T. solani on healthy tubers. A quarantine period is necessary to ensure that tubers are free of the fungus.
Related invasive species
- Thecaphora solani
Related Farm Practice
- Canning
- Rooting
- Development
T. solani is a smut fungus attacking tubers and underground stems of Solanum, including potato [ Solanum tuberosum ] and tomato [ Solanum lycopersicum ], in the Andean region of South America. It is not restricted to the higher, cooler elevations, but has been a problem in coastal Peru (Bazan de Segura 1960;Zachmann and Baumann, 1975) and also occurs in Mexico. It may be transported in infected tubers and planting material and, very likely, on their surfaces if they become contaminated with the spores. The fungus survives in the soil and is difficult to eradicate;it can infect at least one common solanaceous weed. Losses of 80% or more have been reported in susceptible varieties. EPPO lists it as an A1 plant pest (OEPP/ EPPO, 1979).
No symptoms are visible above ground. Infected tubers are misshapen or have warty swellings on the surface, and are hard. The whole or only part of the tuber may be infected. Numerous brown-black specks, interspersed with lighter-brown specks, can be seen in the flesh. The specks (spore sori) are 1 to 4 (or more) mm diameter and are filled with rusty brown spore balls. Completely infected tubers later become dry brown powdery masses of numerous spores. Galls resembling deformed tubers develop on the stems or stolons underground, often encircling them. Roots are not infected. On tomato [ Solanum lycopersicum ], galls develop particularly at the junction of the stem and roots.
For more information, see Barrus and Muller (1943), O'Brien and Thirumalachar (1972), Mordue (1988) and Torres (2001).
The principal host is potato [ Solanum tuberosum ], but various other tuber-bearing species of Solanum are attacked, particularly Solanum tuberosum subsp. andigenum, as well as Solanum lycopersicum (tomato), and the solanaceous weed, Datura stramonium (Mordue, 1988).