Screening cassava cultivars for resistance to the cassava anthracnose disease (CAD)

Forty-seven cultivars of cassava in IITA's trials were screened for their reaction to infection by Colletotrichum gloesporiodes f. sp. manihotis in the field. The following parameters were observed: (a) distance of first canker from the soil, (b) total number of cankers per plant, (c) size of cankers on young stem and shoot, (d) size of canker on material stem, and (e) size of cankers mature stems. Cultivars Isunikankiyan, 81/00110, 82/00142, and 84751 had cankers developing at the lowest level showing that they were infected earlier in life whereas cultivars 81/01476, 30211, 60506, 82/00142, and 30001 had cankers higher up on the stem. These cultivars had tuberized before the onset of the disease hence yield may not adversely affected. Cultivars 81/00401, 82/00058, and 82/00142 had the highest number of cankers per plant whereas the least number of cankers were on cultivars 30211, 80/00141, 4(2)1443, 30337, and 82/00959. Cultivars 81/00086, 82/000142, 81/00401, and 60506 had the largest cankers on young stems and shoots whereas cultivars 30211 and 83/01737 had the smallest cankers. Cultivars Isunikankiyan and 82/00058 had the largest cankers on maturing stems whereas cultivars 83/01737, 30211, and 60506 had the smallest. Cultivars 81/00086, 82/00058, and 83/000765 had the largest cankers on mature stems whereas cultivars 80/01476, 30211, and 83/01737 had the smallest cankers. These results show that cultivars 30211, 80/01476, and 83/01737, with higher resistance to anthracnose disease, can be recommended for further improvement through breeding