On shoots and both sides of ohia leaves, reddish spots were the first symptom of the rust disease (Fig. 1a). The reddish spots gradually became raised, and tiny bright-yellow uredinial sori appeared on the spots (Fig. 1b). Uredinial sori were produced at the center of these spots and erupted (Fig. 1d). The sori increased in diameter and coalesced after production of urediniospores. Shoot tips and leaves where sori were abundant became brown and deformed.