Tebuthiuron [N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]N,N'-dimethylurea] controls small trees in regrown pinyon-juniper woodland chainings. Precise applications by hand minimize cost and damage to forage plants. Little information exists on the applicability of local trials to varying Intermountain sites slated for reinvestment. We conducted 2 balanced factorial experiments at well-separated sites in the Great Basin and Colorado Plateau. Four rates (0.12, 0.25, 0.50, and 0.75 gm a.i. per 130 dm3 crown volume) of tebuthiuron boluses were applied to tree stembase, mid-crown, or dripline placements. Four size classes (12-99, 100-299, 300-599, and 600-1099 dm3 crown volume) of Utah juniper [Juniperus osteosperma (Torr.) Little] and single needle (Pinus monophylla Torr. and Frem.), and Rocky Mountain (P. edulis Engelm.) pinyon trees were treated in September 1985. Defoliation and mortality levels were estimated 24 and 36 months following treatments. Both sites received highly similar amounts of herbicide and cumulative precipitation. Analysis of variance showed that the presence and strength of main effects and first order interactions was largely site-specific. Pinyon was more susceptible than juniper at tither site. Medium-sized and large saplings were apparently more readily defoliated than seedlings and small saplings. Dosage effects were generally nonlinear for both species. The highest, most rapid and most uniform defoliation and mortality of trees resulted from application of tebuthiuron at the stem bases. This placement option has strong operational advantages and minimizes damage to forage plants beneath trees. This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries. The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information. Migrated from OJS platform August 2020
Scholarly peer-reviewed articles published by the Society for Range Management. Access articles on a rolling-window basis from vol. 1, 1948 up to 5 years from the current year. Formerly Journal of Range Management (JRM). More recent content is available by subscription from SRM.