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Etiology

Distribution of the A¹ Mating Type of Phytophthora cinnamomi. G. A. Zentmyer, Professor of Plant Pathology, University of California, Riverside, CA 92502; Phytopathology 66:701-703. Accepted for publication 12 November 1975. DOI: 10.1094/Phyto-66-701.

Our isolations and reports in the literature show that the A¹ compatibility or mating type of Phytophthora cinnamomi has a more limited distribution, both geographically and by host, than the A² type. The A¹ type has been reported from Australia, Malagasy Republic (Madagascar), Papua New Guinea, South Africa, and the United States; the host list for the A¹ type includes only 11 plants in 10 genera. The A² type is world-wide in distribution, and has several hundred hosts. Most of the A¹ isolates resemble the type culture in cultural appearance, although some vary considerably phenotypically and in growth rate.