Phytophthora capsici, Corrected Name for the Cause of Phytophthora Blight of Macadamia Racemes

Abstract

One of the causal organisms of Phytophthora blight of macadamia [Macadamia integrifolia] racemes, originally identified as most closely resembling P. nicotianae var. parasitica, is herein referred to P. capsici. Unlike P. nicotianae var. parasitica, the fungus did not produce chlamydospores after mycelial mats were submerged in water at 16.degree. C for 2 wk. It produced abundant ellipsoidal sporangia with a length-to-width ratio of approximately 2.0. The sporangia were readily detachable; substantial portions of the sporangiophore remained attached and resulted in conspicuous pedicels which average 144 .mu.m in length.