Diseases

Tobacco root rots

Nicotiana tabacum L.

The disease is represented primarily by black root rot, caused by the fungus Thielaviopsis basicola, and dry root rot, caused by Olpidium nicotianae.

In the reference 35 varieties crop Tobacco, where this is mentioned in the description.

The primary pathogen of black root rot in tobacco is the soil-borne fungus Thielaviopsis basicola, also known as Berkeleyomyces basicola or B. rouxiae. In seedlings, the disease manifests as wilting and root necrosis, while in mature plants, it results in stunted growth and characteristic black-brown lesions on the root system. Microscopic examination of infected plant tissues reveals characteristic chains of brown-black thick-walled chlamydospores.

Dry root rot of tobacco is caused by the fungus Olpidium nicotianae (synonym O. radicis), leading to thinning, shriveling, and subsequent necrosis of the roots, which triggers wilting in young plants. Although there is no international classification of pathotypes for the black root rot pathogen, the variability in the aggressiveness of its isolates is well-known.

Genetic resistance to Thielaviopsis basicola in tobacco is inherited as a dominant monogenic trait derived from wild species, specifically Nicotiana debneyi. In breeding practice, cultivar resistance is assessed descriptively; relatively resistant forms include such varieties as Trapezond 245, American 307, and Ostrolist 451.

General information about the subject — on the page Root rots.

Sources8

Varieties of Tobacco 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.