Abstract A description is provided for Leveillula cylindrospora . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Powdery mildew of members of the Chenopodiaceae. Mycelium and ascomata form white, then dirty-grey layers on damaged green parts of the host. The fungus is potentially dangerous for some cultivated plants, for example, beet. Records from Italy and Corsica identified as Leveillula taurica s.l. on Beta maritima (Amano, 1986) probably belong in L. cylindrospora . HOSTS: Atriplex halimus, A. sphaeromorpha, A. tatarica, A. turcomanica, Ceratoides fruticulosa, C. papposa, Chenopodium album, C. ambrosioides, C. anthelminticum, C. murale, C. rubrum, Corispermum hyssopifolium, Kochia prostrata, K. scoparia, K. sieversiana, Noaea mucronata, Salsola arbuscula, S. australis (incl. S . iberica & S. ruthenica ), S. canescens, S. kali, S. laricifolia, S. paletzkiana, S. richteri, S. soda, S. tamamschjanae (Chenopodiaceae). [Type host - Ceratoides papposa ( Eurotia ceratoides )] GEOGRAPHICAL DISTRIBUTION: Africa: Canary Islands, Morocco. Asia (temperate areas only): Azerbaijan, Armenia, China, Republic of Georgia, Iran, Israel, Kazakhstan, Kirghizstan, Korea, Lebanon, Pakistan, Russia (north Caucasus, south Siberia), Tadzhikistan, Turkey, Turkmenistan, Uzbekistan. Europe: France, Italy, Portugal, Rumania, Russia (southeastern areas of European part, south Urals), Spain, Turkey (European part), Ukraine (southern). TRANSMISSION: By wind-dispersed conidia. The rôle of ascospores in disease transmission is unknown, although it has been supposed that they can cause the initial stage of the disease, because ascomata containing asci and ascospores have been observed after winter (Gaponenko et al. , 1983, p. 177).