Mechanical Site Preparation and Early Chemical Tending in White Spruce: 19-year Results

A white spruce outplanting trial, with about 480 trees, was established on a fertile mixedwood site in Ontario (47°N, 84°W) in 1967 to study the effects of two site preparation methods and early chemical tending on the development of the crop species and non-crop woody vegetation. Nineteen-year results are presented. Early chemical tending of white spruce resulted in a significant increase in growth on the drum-prepared block, but not on the blade-prepared block. On the drum-prepared block, mortality of white spruce outplants did not differ significantly between herbicide-treated and untreated plots. On the blade-prepared block, mortality was significantly greater with herbicide application than without it. Similar non-crop tree and shrub species were found on sites prepared with both sharkfin drums and angle-dozer blades. However, woody weeds were less abundant on the herbicide-treated plots than on the untreated plots. Key words: white spruce outplant performance; chemical weed control; 2.4-D and 2,4,5-T; mechanical site preparation; herbicide efficacy; silvicultural efficacy; early tending; sharkfin drum; angle-dozer blade.