Dactuliochaeta glycines. [Descriptions of Fungi and Bacteria].

A description is provided for Dactuliochaeta glycines. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Glycine max (soyabean), G. javanica (= Neonotonia wightii). DISEASE: Red leaf blotch or Pyrenochaeta leaf blotch of soyabean. Symptoms which appear on leaves, pods and stems are small dark brown circular to elliptical or occasionally irregular lesions, 1-2 mm wide with dark margins. With the advancement of infection lesions enlarge up to 2-3 cm wide but often coalesce to form large blotches covering > 50% of the leaf surface. Older lesions become necrotic, grey to dark brown in the centre with a dark brown or nearly black margin. Some lesions are surrounded by a chlorotic halo. Affected leaves become chlorotic and fall. In Ethiopia up to 75% defoliation has been reported in some varieties of soyabean. Initially it was reported that soyabean varieties with pale leaves were more susceptible than those with dark ones (Stewart, 1957) but recently it has been reported that soyabean with dark or light green foliage are equally susceptible (Hartman et al., 1987). Lesions on Neonotonia wightii are generally circular and larger (< 4 cm diam.) than those on G. max. GEOGRAPHICAL DISTRIBUTION: Africa (Cameroon, Ethiopia, Malawi, Mozambique, Rwanda, Tanzania Uganda, Zaire, Zambia, Zimbabwe); Asia (India); South America (Bolivia). TRANSMISSION: By soil-borne sclerotia and pycnidia dispersed by rain-splash. Heavily infected leaves with sclerotia and pycnidia left on the ground may serve as inoculum for the next growing season (Hartman et al., 1987). Primary inoculum is presumed to come from infected Neonotonia wightii which is widely distributed or from alternate hosts but the full host range has not been investigated. Longevity of sclerotia, pycnidia and conidia left in the soil has not been quantitatively assessed.