Phytophthora Diseases of Orchids in Hawaii

Abstract

In Hawaii, Phytophthora palmivora is a major fungal pathogen of orchids, causing large black foliar rots, root losses, and seedling damping-off of Dendrobium, Cattleya, Epidendrum, Vanda, Paphiopedilum, Laeliocattleya, and a few other intergeneric hybrids. Recently, it has also been associated with blossom spots and rots of Dendrobium and Vanda. Phytophthora nicotianae (commonly known as P. parasitica) also occurs on most of the above orchids. Phytophthora cinnamomi is an occasionally important pathogen of cymbidium roots, and P. cactorum has also been observed on cymbidium, but only infrequently.