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Shoot Blight of Pistachio Caused by Botrytis cinerea. H. A. Bolkan, Associate Professor, Department of Biological Sciences, University of Brasilia, Brasilia, DF 70.910, Brazil. J. M. Ogawa, Professor, Department of Plant Pathology, University of California, Davis 95616, and H. R. Teranishi, Farm Advisor, Madera County, Cooperative Extension Service, Madera, CA 93637. Plant Dis. 68:163-165. Accepted for publication 14 October 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-163.

A shoot blight disease caused by Botrytis cinerea is reported for the first time on pistachio (Pistacia vera) in California. Shoot blighting resulted from initial infection of catkins and racemes and progress of the fungus into stems. Partial girdling of shoots or twigs resulted in shriveled leaves showing necrosis from water stress. Petiole infections resulted in death of individual leaves and/or shoot blight. Incidence of the disease was high on male trees because of the high susceptibility of catkins. The disease was favored by prolonged rainfall and relatively low temperatures. Fungicides applied during full bloom of male flowers and partial bloom of female flowers reduced the number of blighted shoots. Benomyl was the most effective fungicide under field conditions.