ASCOCHYTA BLIGHT OF LENTIL AND ITS CONTROL IN ETHIOPIA

An Ascochyta sp. was consistently isolated from ascochyta blight-affected lentil (Lens culinaris Medik.) seed and plants. The fungus was pathogenic only to lentil and not to any of seven other legume species tested. Based on the cultural and morphological characteristics, pathogenicity and host range tests the causal fungus was identified as Ascochyta lentis Vassilievsky. The symptoms of the disease on lentil leaves, stems and pods are necrotic lesion speckled with brownish pycnidia. The seed-borne nature of the fungus was confirmed. In a 3-year field trial, chlorothalonil (Bravo 500), benomyl (Benlate) and a mixture of tridemorph and maneb (Calixin M) provided the best disease control and highest yields. The hot-water and dry-heat treatments at 55-degrees-C for 25 min and 70-degrees-C for 24 h gave partial inhibited fungal growth from seed. None of the 139 accessions tested was immune; 35 were identified as resistant, whereas the remainder were moderately resistant to susceptible. Seed transmission of the fungus varied in different genotypes according to their resistance reaction.