Disease expression in plants derived from cassava cuttings with different levels of infection with African cassava mosaic virus

Abstract

In the field, three symptom-types of African cassava mosaic virus infection are recognized in the cassava variety TMS4 (2) 1425, namely symptomless, partially symptomatic, and fully symptomatic plants. Main stem cuttings developed into plants with a significantly higher disease incidence than primary branch cuttings, particularly when derived from partially symptomatic plants in which one of the primary branches was healthy. Approximately a 10% disease incidence was observed in plants which developed from main stem cuttings of symptomless plants while those from primary branch cuttings remained healthy. Apart from symptomless plants, the reduced tendency of healthy branches of partially symptomatic plants to show reversion permits them to serve as potential sources of healthy cuttings.