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Etiology

A Bacterial Leaf Spot Caused in Yam Bean by Pseudomonas syringae pv. phaseolicola. Robert G. Birch, Graduate student, Department of Plant Pathology, University of Hawaii, Honolulu 96822; A. M. Alvarez(2), and Suresh S. Patil(3). (2)(3)Assistant plant pathologist, and professor, respectively, Department of Plant Pathology, University of Hawaii, Honolulu 96822. Phytopathology 71:1289-1293. Accepted for publication 20 March 1981. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-1289.

A bacterium causing leaf spot of yam bean, Pachyrrhizus erosus, in Hawaii was identified as Pseudomonas syringae pv. phaseolicola on the basis of in vitro biochemical properties; symptoms induced in yam bean, Red Kidney bean, and detached bean pods; remission of toxin-induced systemic symptoms at elevated temperatures and behavior in a microbial assay for antimetabolic toxins. It is distinct from Pseudomonas syringae pv. syringae and pv. tabaci in each of these aspects. Also, the phytotoxin produced by the yam bean pathogen in culture and in the plant strongly inhibits ornithine carbamoyltransferase activity, which is typical of pv. phaseolicola. Yam bean may be a significant alternative host for the bean halo-blight pathogen in tropical regions.