Abstract

The effect of mosaic virus diseases on dry matter content and starch yield of five local accessions of cassava, “Ankrah”, “AW/17, “Tomfa”, “Dagarti” and “Tuaka” was evaluated. Tomfa showed the highest (95%) incidence of the disease, index of severity of symptoms for all plants (ISS_AP) of 3.70, as well as, for diseased plants (ISS_DP) (3.84) while Dagarti did not show any phenotypic expression of the disease throughout the study period. Most of the accessions displayed mosaic disease symptoms two months after planting but by the fifth month had fully recovered. However, PCR-based testing at 12 months after planting revealed the presence of ACMV in all the accessions while EACMV was observed in Ankrah, Dagarti and AW/17.  Mean tuber (fresh root weight) and starch yield at 12 months after planting (MAP) was significantly (P ≤ 0.05) high in Ankrah while percentage dry matter was significantly higher in Dagarti than the other accessions. A negative correlation between starch yield and cassava mosaic disease incidence implies that a high mosaic incidence particularly in the first three months results in lower tuber and starch yields.

Key words: Mosaic virus diseases, dry matter, starch yield, PCR, disease incidence