Stimulation of Resinosis and Apparent Inhibition of Blue Stain Development in Ponderosa Pine by Paraquat
Abstract The effects of stemfrill application of paraquat solution concentration (1, 8, 16, and 30 percent), volume (5, 10, and 20 ml), and date of application (8-9 July and 21-22 August) on resinosis in sapwood of Pinus ponderosa were evaluated. The greatest yield of extractives resulted from treatment with 10 ml of an 8 percent solution applied 8-9 July. No qualitative changes in oleoresin composition attributable to paraquat application were detected by gas-liquid chromatography of the terpene fraction. Blue stain development was inhibited above treatment frills. This inhibition was greatest following treatment with 20 ml of 8 percent paraquat applied on 8-9 July. Growth of Ceratocystis montia, a fungal symbiont of the mountain pine beetle was prevented by paraquat at concentrations above 5 ppm in malt-agar medium. Forest Sci. 25:569-575.