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Landscape Survival of Fungicide-Treated Azaleas Inoculated with Phytophthora cinnamomi. D. M. Benson, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. . Plant Dis. 74:635-637. Accepted for publication 2 February 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0635.

Containerized Hinodegiri azalea in a pine bark:sand medium were inoculated with oat grains colonized by Phytophthora cinnamomi. Plants were treated with three foliar sprays of fosetyl-Al (4.79 g a.i./L), with two drenches of metalaxyl (0.078 ml a.i./L), or left untreated over the next 61 days before being transplanted to pathogen-free landscape beds. The long-term growth and survival of plants in beds after discontinuation of fungicide treatment was compared to plants in a fourth group left untreated and uninoculated as a control. Only a few fungicide-treated, inoculated plants developed symptoms of Phytophthora root rot after 3 yr in the beds. Plant growth of fungicide-treated inoculated plants over the 3-yr period was comparable to that of untreated, uninoculated controls. However, untreated, inoculated plants were significantly smaller in size, and mortality reached 39% after 3 yr. Results suggest that application of fungicides to inoculated plants in containers was sufficient to prevent Phytophthora root rot after transplanting to pathogen-free landscape beds.