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Disease Control and Pest Management

Effect of Benomyl on Phomopsis juniperovora Infection of Juniperus virginiana. J. D. Otta, Associate professor, Department of Plant Science, South Dakota State University, Brookings, SD 57007; D. J. Fiedler(2), and V. H. Lengkeek(3). (2)(3)Former assistant-in, and former graduate research assistant, respectively, Department of Plant Science, South Dakota State University, Brookings, SD 57007. Phytopathology 70:46-50. Accepted for publication 23 July 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-46.

Growth of Phomopsis juniperovora was reduced in vitro by benomyl concentrations as low as 0.25 mg/L. Benomyl applied as a soil drench to Juniperus virginiana in the greenhouse was translocated to the foliage. Foliage was protected from Phomopsis blight whenever fungitoxicant in the new growth exceeded 3 μg/g of fresh weight. Benomyl applied as a spray to the foliage was not translocated to portions of the foliage protected from the spray. Benomyl applied as a spray to J. virginiana during their third growing season in a nursery significantly reduced: the incidence of Phomopsis blight, the disease severity on infected trees, the length of diseased tissue (mm) on infected trees with pycnidia of P. juniperovora, and the percent of pycnidia containing spores. None of the benomyl spray or drench treatments prevented spore germination or initial infection. Infection studies in the field indicated that J. virginiana was susceptible to P. juniperovora throughout the growing season.

Additional keywords: Phomopsis blight.