Diseases
Spongospora subterranea (Wallr.) Lagerh. - Powdery Scab of Potato
Systematic position.
Division Myxomycota, genus Spongospora.Biological group.
Obligate parasite.Morphology and biology.
The cause of Powdery Scab of Potato (S.subterranea) has multinuclear plasmodium to 70mkm in size. They form dense lumps of spores in affected cells. In soil the spores release zoospores to 2.5-4.6 mkm in diameter, which infect tubers and roots of potato. Sometimes they also infect stolons. The parasite can affect tomatoes and others Solanaceae. The disease appears on the tuber surface as deepened star-shaped open ulcers filled with numerous brown lumps of spores. Tumors are formed on the affected roots. Sources of the infection are spores, which can be kept in soil over five years, and affected tubers.Distribution.
Powdery Scab of Potato is registered in Belarus and in separate regions of Northwest, Volga-Vyatka, and Central regions of Russia.Ecology.
The disease appears in conditions of sufficient humidifying and low temperature of soil.Economic significance.
Strongly affected tubers are completely destroyed. The disease reduces significantly food and commercial quality of potato and promotes its affection by saprogenic microorganisms. The most effective control measures against S.subterranea are 5-year crop rotation and presowing fungicide treatment of seed tubers.Related references:
Ginfner K., Chak Z. 1958. Diseases and damage to potato tuber. Budapest: Academy of Sciences of Hungary, p.24-25 (in Russian).Gorlenko M.V. 1968. Powdery scab of potato. Agricultural phytopathology. Moscow: Vysshaya shkola, p.260-261 (in Russian).
Pidoplichko N.M. 1977. Fungal parasites of cultural plants. Guide, vol.1. Kiev: Naukova Dumka, 299 p. (in Russian).
Sizova T.P. 1976. Division Myxomycota. Fungi. Moscow: Prosveshchenie, p.7-12 (in Russian).
Volovik A.S., Borisenok A.B., Erokhina S.A., Zakharova T.I. 1971. Fungal diseases of potato. In: Polyakov I.Ya., Minkevich I.I., eds. Pests and diseases distribution on agricultural crops in RSFSR in 1970 and the forecast of their appearance in 1971. Moscow: MSKH RSFSR, VIZR: p.168-178 (in Russian).