Evaluation of Systemic Fungicides for Control ofCronartium quercuumf. sp.fusiformeon Loblolly Pine Seedlings

Abstract

KELLEY, W. D. 1980. Evaluation of systemic fungicides for control of Cronartium quercuum f. sp.fusiforme on loblolly pine seedlings. Plant Disease 64:773-775. 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. ferbam to control fusiform rust in nurseries and the damage to nursery beds from maneuvering spray equipment through the nursery during wet weather are major concerns of nursery managers. This paper reports results of preliminary screening tests with four experimental systemic fungicides to identify alternatives to ferbam for control of fusiform rust. A preliminary report has been published (3).