Phytophthora Root Rot of Commercially Cultivated Proteas in South Africa. S. L. Von Broembsen, Agricultural Researcher, Plant Protection Research Institute, Private Bag X5017, Stellenbosch 7600. G. J. Brits, Agricultural Researcher, Horticultural Research Institute, Tygerhoek Experimental Farm, P.O. Box 25, Riviersonderend 7250. Plant Dis. 69:211-213. Accepted for publication 25 June 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-211.

Phytophthora cinnamomi was isolated from the roots of 63 species of diseased proteas (Proteaceae) in commercial fields in the South Western Cape Province of South Africa. Disease was often associated with poor soil drainage. Aboveground symptoms ranged from wilting and rapid death to chlorosis, decline, and eventual death. P. cinnamomi was associated most frequently with Leucospermum and Leucadendron spp. Pathogenicity of P. cinnamomi to indigenous proteas in eight genera (Leucadendron, Leucospermum, Protea, Aulax, Brabeium, Mimetes, Paranomus, and Serruria) was demonstrated by artificial inoculation.

Keyword(s): disease control.