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Ozone Injury to Tobacco in the Field Influenced by Soil Treatments with Benomyl and Carboxin. G. S. Taylor, The Connecticut Agricultural Experiment Station, New Haven, 06504; Saul Rich, The Connecticut Agricultural Experiment Station, New Haven, 06504. Phytopathology 64:814-817. Accepted for publication 30 December 1973. DOI: 10.1094/Phyto-64-814.

In field plots under shade tents, soil treatments of carboxin at 5 and 10 µg/g and benomyl at 25 µg/g were tested for their ability to protect tobacco cultivar Conn. 7272 against flecking caused by ozone. Plants growing in soil treated with carboxin had significantly less fleck on their first three leaves than did nontreated plants; but on most of the subsequent leaves the carboxin-treated plants had more fleck than the untreated plants. The plants growing in soil containing carboxin at 10 µg/g were stunted and their leaves developed yellow margins. In the benomyl treated plots, the plants had significantly less flecking on their first eight leaves, but the upper leaves were not protected later in the season. These plants were more vigorous than those in either the carboxin-treated or untreated plots, appeared to have many more fine, white, feeder roots and their roots contained fewer tobacco cyst nematodes.