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The Effect of Benomyl on the Growth of American Elm Seedlings. B. R. Roberts, Plant Physiologist, Plant Science Research Division, ARS, USDA, Delaware, Ohio 43015; W. K. Hock(2), and L. R. Schreiber(3). (2)(3)Plant Pathologists, respectively, Plant Science Research Division, ARS, USDA, Delaware, Ohio 43015. Phytopathology 63:85-87. Accepted for publication 11 July 1972. DOI: 10.1094/Phyto-63-85.

Benomyl was applied either as a drench to 10-month-old American elm seedlings or incorporated directly as a dry mix into media (sand, soil, potting mix) subsequently planted with elm seed. Benomyl at concentrations of 1,000 and 1,500 ppm had no significant effect on height, dry weight, leaf area, or root:shoot ratio. Germination of elm seed in planting media containing dry benomyl was generally poor. Fourteen weeks after germination, growth was approximately the same in benomyl-treated sand and soil, but substantially greater in benomyl-treated potting mix. The size of inhibition zones around tissue sections from benomyl-treated plants indicates acropetal transport of this fungicide in the xylem, appreciable lateral movement into the phloem, and substantial accumulation in the foliage.