Evaluation of Systemic Fungicides for Control of Cronartium quercuum f. sp. fusiforme on Loblolly Pine Seedlings. W. D. Kelley, Assistant Professor, Department of Botany, Plant Pathology, and Microbiology, Auburn University Agricultural Experiment Station, Auburn, AL 36830. Plant Dis. 64:773-775. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-773.

Four experimental systemic fungicides applied individually as preplant incorporated soil treatments and as foliar sprays were evaluated for controlling fusiform rust on loblolly pine (Pinus taeda) seedlings. Seedlings were inoculated with Cronartium quercuum f. sp. fusiforme and were evaluated for gall formation after 36 wk. Of the four fungicides tested, only triadimefon (Bayleton) effectively controlled fusiform rust. No stem galls developed on seedlings in soil in which triadimefon had been incorporated as a preplant treatment at a rate of 2 kg a.i./ha. Triadimefon applied as a foliar spray at a rate of 0.56 kg a.i./ha eradicated rust infections that occurred up to 7 days before treatment and provided protection against the pathogen for 14–21 days after application. No phytotoxic effect of triadimefon on seedling growth was observed, and no significant differences were observed between the fungicide-treated seedlings and the controls concerning the presence of basidiocarps of the mycorrhizal symbiont Thelephora terrestris.