Effect of canker size on availability of cassava planting materials in Nigeria

Cassava (Manihot esculenta L.) production is highly limited by cassava anthracnose disease (CAD) which causes significant losses in planting materials. An experiment was laid out at Ihiagwa, Owern in Nigeria with eighteen treatments replicated three times. Disease severity was scored on a scale of 1-5, and disease incidence was recorded as the percentage of infected plants in each host plant line. In all the three trials, TMS 30211 (425 mm) had cankers high up on the stem, showing that they were infected later in life. This will lead to more disease - freestems. Cultivars Akwakwuru (39.6 mm2), TMS 30555 (31.6 mm2), and Nwaocha (43.7 mm2), had the large canker size on whole plant, young stem, shoot and maturing stem. These cultivars had low resistance to anthracnose. In all the trials, TMS 4(2)1425, and TMS 30211, had the smallest canker size (1.80 and 6.3 mm2, respectively) on whole plant, young stems, shoots and maturing stems. TMS 4(2)1425 and TMS 30211 had higher resistance to anthracnose and can be recommended for further improvement through breeding, because plants producing smaller – size lesions survive much longer and would also mature and produce flowers needed for breeding for improving resistance to CAD and other diseases