Leptosphaeria salvinii . [Descriptions of Fungi and Bacteria

Abstract

Abstract A description is provided for Leptosphaeria salvinii [Magnaporthe salvinii] . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Oryza sativa . DISEASE: Stem rot of rice ( Oryza sativa ). Symptoms are usually first seen at the later growth stages. Necrotic lesions begin on the outer leaf sheath near the water line; these spread gradually to the inner sheaths and the stem base. At about maturity lodging may occur and sclerotia will be found within the tissues. Partial sterility is caused and grain becomes light and chalky. Late infection can lead to small tillers but whether the pathogen caused excessive tillering, as earlier reports stated, is in doubt. Sclerotia form conidia when floating free or detached on moist substrata. Symptoms seem to vary with the growing conditions. GEOGRAPHICAL DISTRIBUTION: Widespread with host (CMI Map 448, ed. 1, 1968). Additional records not mapped are: Costa Rica, Indonesia, Laos, Panama, Peru. TRANSMISSION: Probably largely through the sclerotia; the role of the conidium and ascospore has been little studied. Viability of the sclerotium is variable, depending on temperature and substratum conditions (11: 599; 47, 182), and a period of 6 yr has been reported (20: 381). Both sclerotia and perithecia survive high summer temperatures (46, 1574).