Bacterial Blight of Kiwifruit in California. K. E. Conn, Department of Plant Pathology, University of California, Davis 956126. W. D. Gubler, and J. K. Hasey. Department of Plant Pathology, University of California, Davis 956126, and Farm Advisor, University of California, 142-A Garden Highway, Yuba City 95992. Plant Dis. 77:228-230. Accepted for publication 3 November 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0228.

Flower bud rot, blossom blight, and leaf spot of kiwifruit (Actinidia deliciosa) have been observed in numerous commercial orchards in California since 1986. As the diseased flower buds develop, petals become yellow-orange, then brown, and the entire bud falls from the vine. Fruit may be small, misshapen, or fail to set. The bacterial pathogens Pseudomonas syringae and P. viridiflava, in addition to the saprophyte P. fluorescens, consistently have been isolated from both symptomatic and asymptomatic vines throughout the spring. In pathogenicity tests, P. viridiflava caused significantly more flower bud rot and blossom blight, but not leaf spot, than P. syringae. P. fluorescens was not pathogenic.