Avocado Sunblotch

Abstract

The sunblotch disease of avocado has been known for over 50 years. It was first described as a physiological (Coit, 1928) or genetic (Home, 1929) disorder. Shortly thereafter, Horne and Parker (1931) transmitted the causal agent from diseased scions to healthy rootstocks. By 1941, graft transmissibility of the agent was well established (Horne et al., 1941). Hence, the causal agent was considered to be a virus, and like some of the other plant viroids was studied as such for many years (Whitsell, 1952; Wallace, 1958; Wallace and Drake, 1962; Desjardins et al., 1980).