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Phytophthora Blight, a New Disease of Macadamia. J. E. Hunter, Assistant Plant Pathologist, Department of Plant Pathology, University of Hawaii, Hilo 96720; R. K. Kunimoto(2), and K. G. Rohrbach(3). (2)Junior Plant Pathologist, Department of Plant Pathology, University of Hawaii, Hilo 96720; and (3)Plant Pathologist, Pineapple Research Institute, Wahiawa, Hawaii 96786. Phytopathology 61:1130-1134. Accepted for publication 26 April 1971. DOI: 10.1094/Phyto-61-1130.

Phytophthora blight of macadamia, caused by Phytophthora nicotianae var. parasitica and Phytophthora palmivora, is a new disease which has been observed following periods of prolonged rain at three locations on the island of Hawaii. Under these conditions, a majority of the racemes and nuts were destroyed. Phytophthora nicotianae var. parasitica but not P. palmivora survives in the dead racemes which remain attached to the branches between flowering periods, and serve as the source of inoculum for new infections. Phytophthora nicotianae var. parasitica is more virulent than P. palmivora.