Previous View
APSnet Home
Phytopathology Home


Etiology and Epidemiology

Variability in Growth of Phytophthora cinnamomi in Relation to Temperature. G. A. Zentmyer, Professor, Department of Plant Pathology, University of California, Riverside 92502; J. V. Leary(2), L. J. Klure(3), and G. L. Grantham(4). (2)(3)(4)Assistant Professor, and Staff Research Associates, Department of Plant Pathology, University of California, Riverside 92502. Phytopathology 66:982-986. Accepted for publication 4 February 1976. Copyright © 1976 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-66-982.

Growth of 187 isolates of Phytophthora cinnamomi (20 A1, 167 A2 mating type) from 24 countries and 59 hosts was compared at 25 C on potato-dextrose agar. The frequency distribution obtained for these isolates closely approximated a normal curve, with 90 isolates below the mean and 97 above. Colony diameters after 4 days of growth ranged from 41 to 85 mm. Nutrition affected the growth-temperature response; some isolates grew rapidly on one medium and slowly on another medium at 25 C. On minimal medium at 25 C with and without β -sitosterol the mean growth rate for A1 mating type isolates of P. cinnamomi was significantly slower than for A2 isolates; on clear V-8 agar there was no significant difference between the two mating types. At 30 and 33 C on minimal medium, three A1 isolates grew more rapidly than 16 other isolates that included 12 A2 and 4 A1 types. Our studies, plus other reports, indicate that the cardinal temperatures for P. cinnamomi range from: minimum, 5-16 C; optimum, 20-32.5 C; and maximum, 30-36 C.

Additional keywords: nutrition, mating type.