VIEW ARTICLE

Identification of Four Phytophthora Isolates Previously Unreported from Arizona. Jerald E. Wheeler, Postdoctorate, Biologisches Institut II, Freiburg, West Germany; Alice M. Boyle, Professor, Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 61:1293-1296. Accepted for publication 11 May 1971. DOI: 10.1094/Phyto-61-1293.

Arizona isolates of Phytophthora from Rosmarinus officinalis, Leucophyllum frutescens, Washingtonia spp., and Petunia spp. were identified as P. parasitica on the basis of morphological and physiological similarity to citrus isolates of P. parasitica from Arizona and California. Colony characteristics and distinguishing characters of sporangia were similar to those of an Arizona isolate of P. parasitica from citrus. Ooospores seldom developed in pure cultures or when the five were paired in all possible combinations. Malachite green reduced growth of all isolates at concentrations above 0.10 µg/ml. Optimum growth of all isolates occurred at 30 C, and was entirely inhibited at 38 C. All isolates used mannose, xylose, maltose, fructose, dextrose, and sucrose as a carbon source except the rosemary isolate, which did not use xylose. Asparagine was the most favorable source of nitrogen for all isolates. All isolates infected rosemary and sweet orange stems and fruits, but differed in virulence. Only the petunia isolate was pathogenic to petunia.