VIEW ARTICLE

Ecology and Epidemiology

Synergistic Interactions Between Verticillium dahliae and Pratylenchus penetrans in Potato Early Dying Disease. R. C. Rowe, Professor, Department of Plant Pathology, The Ohio State University (OSU), Ohio Agricultural Research and Development Center (OARDC), Wooster 44691 and Columbus 43210; R. M. Riedel(2), and M. J. Martin(3). (2)(3)Professor and former graduate student, Department of Plant Pathology, The Ohio State University (OSU), Ohio Agricultural Research and Development Center (OARDC), Wooster 44691 and Columbus 43210, (3)Current address: Research biologist, E. I. DuPont deNemours & Co. Inc., Agricultural Chemicals Department, P.O. Box 30, Newark, DE 19714. Phytopathology 75:412-418. Accepted for publication 15 October 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-412.

Field microplot studies were conducted on fumigated soil of two soil types over four seasons (1980- 1983) to determine effects of Verticillium dahliae and Pratylenchus penetrans on the development of potato early dying disease. Tests with three population levels of P. penetrans and two of V. dahliae, alone and in all combinations, showed that disease occurred when both pathogens interacted synergistically at population levels that individually had little or no effect. Yield reductions of 25- 50% often occurred in the presence of both pathogens. Yield losses were, however, not always associated with foliar symptom development, but were most pronounced in seasons when high-temperature stress occurred during tuberization. The interaction of P. penetrans with V. dahliae in potato early dying is an important factor that must be considered in the development of disease forecasting and crop-loss predictive systems.