Effects of Plant Growth Regulators on Development of Pierce’s Disease Symptoms in Grapevine. D. L. Hopkins, Professor of Plant Pathology, University of Florida, Institute of Food and Agricultural Sciences, Agricultural Research and Education Center, Leesburg 32749-0388. Plant Dis. 69:944-946. Accepted for publication 17 March 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-944.

Foliar applications of indoleacetic acid (IAA) at 200 μg/ml and kinetin at 1,000 μg/ml to Vitis rotundifolia ‘Carlos,’ moderately resistant to Pierce’s disease (PD), prevented the development of PD symptoms in inoculated plants in the greenhouse. These treatments also prevented accumulation of PD bacteria in leaves of the plants. In V. vinifera ‘Carignane,’ a highly susceptible cultivar, growth regulators did not prevent PD symptoms. In contrast, ethephon and abscisic acid slightly enhanced symptom development in Carlos and in the highly resistant V. rotundifolia ‘Higgins.’

Keyword(s): xylem-limited bacteria.