The pathogen
The disease is called algal leaf spot, algal fruit spot, and
green scurf; Cephaleuros infections on tea and coffee
plants have been called “red rust.” These are aerophilic,
filamentous green algae. Although aerophilic and terrestrial,
they require a film of water to complete their
life cycles. The genus Cephaleuros is a member of the
Trentepohliales and a unique order, Chlorophyta, which
contains the photosynthetic organisms known as green algae.