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Ecology and Epidemiology

Origin of Phytophthora cinnamomi: Evidence That It is Not an Indigenous Fungus in the Americas. G. A. Zentmyer, Professor, Department of Plant Pathology, University of California, Riverside, CA 92521; Phytopathology 67:1373-1377. Accepted for publication 16 May 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1373.

Cultures were made from roots from 373 native Persea trees and cultivated avocado trees (Persea americana) in 18 countries including Mexico and countries in Central and South America and the Caribbean. The root samples were collected from 11 species and varieties of Persea and from five other related genera in the Lauraceae. Phytophthora cinnamomi was not recovered from any trees in native, undisturbed sites, or from undisturbed soils in southern California avocado areas, but was readily recovered from roots of trees brought into cultivation and affected with root rot. These data indicate that it is unlikely that P. cinnamomi is an indigenous fungus in the Americas.