A key to Phytophthora species found in Papua New Guinea with notes on their distribution and morphology.

A simple key is given for the most common Phytophthora species found in the soils of Papua New Guinea. Species listed are P. cinnamomi, P. colocasiae, P. cryptogea, P. heveae, P. katsurae, P. megasperma var sojae, P. nicotianae var nicotianae, P. nicotianae var parasitica, P. palmivora and a Phytophthora species placed nearest P. cryptogea. Peronophythora litchii has been included because ofits close resemblance to Phytophthora. All isolations held at Bulolo are listed, together with notes on their morphology.