Variability in Phytophthora Cinnamomi Rands

Abstract

Nine New Zealand and eight overseas isolates of Phytophihora cinnamomi Rands have been compared for vegetative growth and sporulation under a range of temperatures and pH values. Pathogenicity of these isolates was checked on seven species of conifers. Although variation existed amongst the 17 isolates tested, III no case was this sufficient to warrant recognition of distinct strains of the fungus. No evidence was obtained to suggest that P. cinnamomz III New Zealand has become adapted to cooler climatic conditions. It was shown that sporulation does not occur at temperatures which prevail in soil during the normally wet winter months in New Zealand. Thus it is understandable why epidemic losses tend to be restricted to years when rainfall is abnormally high in autumn and late spring when soil temperatures are sufficient to support sporulation. © 1965, Taylor & Francis Group, LLC. All rights reserved.