Observations on Virus Diseases of Cassava in Resistant and Susceptible Varieties I. Mosaic Disease

Abstract

An account is given of the mosaic-disease resistance shown by varieties of cassava in field trials. Experiments showed that a high proportion of the plants of the moderately resistant varieties studied became infected in field trials in which they were exposed to infection by a very large vector population. When conditions favoured the resistance mechanism of the host, no symptoms of infection became evident, and the virus moved to the base of the plant, leaving the upper parts apparently free. Mosaic symptoms appeared more frequently if the growth of the host was interrupted at a time when there was a large vector population.