Ethephon Stimulates Abscission of Eastern Dwarf Mistletoe Aerial Shoots on Black Spruce. W. H. Livingston, Graduate Research Assistant, Department of Plant Pathology, University of Minnesota, St. Paul 55108. M. L. Brenner, Professor, Department of Horticultural Science and Landscape Architecture, University of Minnesota, St. Paul 55108. Plant Dis. 67:909-910. Accepted for publication 31 January 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-909.

Ethephon, an ethylene releasing agent, was sprayed at 1,250, 2,500, and 5,000 μg/g on black spruce (Picea mariana) branches infected with eastern dwarf mistletoe (Arceuthobium pusillum). At the two highest concentrations, the numbers of seeds and aerial shoots on infected branches were reduced 90–100%. Ethephon treatment resulted in partial dieback of dwarf mistletoe brooms.