VIEW ARTICLE

Ecology and Epidemiology

Survival and Host Range of Phytophthora citrophthora in Ohio Nurseries. W. W. P. Gerlach, Former Graduate Research Assistant, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Wooster 44691, Present address of senior author: Standard (Phillippines) Fruit Corp., P. O. Box 362, MAKATI, Rizal, Philippines; H. A. J. Hoitink(2), and A. F. Schmitthenner(3). (2)Associate Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Wooster 44691; (3)Professor, Ohio State University, Columbus 43210. Phytopathology 66:309-311. Accepted for publication 26 August 1975. DOI: 10.1094/Phyto-66-309.

Phytophthora citrophthora survived freezing to –21 C in several nutrient agar media, only if incubated at 4 C during 4 days prior to freezing. It survived –31 C on hemp agar after 4 C conditioning. In the field, it survived in infected leaves from the fall of 1973 until May 1974, both on the soil surface and buried 10 cm deep. Cultures originated from mycelial fragments, and not from other structures. Roots of several woody ornamentals, and/or shoots of others, were susceptible to infection. Shoots and roots of Euonymus radicans var. argenteo marginatus and Rosmarinus officinalis, in addition to those of Pieris japonica, were susceptible. It was concluded that the distribution of P. citrophthora is determined largely by the presence of infected susceptible hosts.