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Disease Detection and Losses

Evaluation of a Selective Medium for Detecting Pseudomonas syringae pv. papulans and P. syringae pv. syringae in Apple Orchards. T. J. Burr, Assistant professor, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456; B. Katz, research technician, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456. Phytopathology 72:564-567. Accepted for publication 17 August 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-564.

A selective, differential medium (PSM) devised for isolating Pseudomonas syringae pv. papulans (Psp) from plant tissues inhibited growth of most microorganisms and facilitated growth of some other Pseudomonas spp. including P. syringae pv. syringae (Pss). The medium proved superior to four other selective and differential media. Psp and Pss could be distinguished visually by differences in colony morphology. PSM was used to isolate Psp and Pss from dormant apple (Malus pumila ‘Mutsu’) buds, leaf scars, blossoms, fruits, and leaves and from five common orchard weeds.