Forest insects and diseases active in immature interior spruce stands in the central interior of British Columbia and their possible implications in forest management practices have been surveyed. Collection records, spanning the period 1949 to 1982, from the Forest Insect and Disease Survey of the Canadian Forestry Service were reviewed for the Prince George Timber Supply Area and the pest incidence in immature interior spruce stands summarized. Twenty-two plantations, established between 1963 and 1973, were surveyed to determine the relative incidence of the major insect and pathogen pests of immature spruce in Supply Block 'G' of the Prince George Timber Supply Area. A bud midge, likely Rhabdophaga swainei Felt (Diptera: Cecidomyiidae), and a terminal weevil, Pissodes strobi Peck (Coleoptera: Curculionidae), were found to consistently infest and damage a significant number of immature interior spruce trees. A spruce stand stocking profile was developed as a basis for discussion of management practices in plantations and immature stands. The stocking profile can be used in the determination of not only pest management policy decisions but in stand management decisions affecting stand density and, ultimately, merchantable yield at harvest. The findings confirmed that forest management must be actively practiced throughout the life of a forest stand. To be successful, however, stand management guidelines and merchantable yield projections are required. These guidelines and projections must include the influences of insects and diseases upon the forest crop in their development model. This information is particularly important in the development of complete Timber Supply Area plans and for the flagging of pest hazard periods during the development of spruce forests. / Forestry, Faculty of / Graduate

Twenty sample plots located in Inonotus tomentosus (Fr.) Teng centers in mixed lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) and interior spruce (Picea glauca x engelmannii Engelm.) stands in central British Columbia were studied to investigate the behaviour of, and variation in host species attacked by the pathogen. The effect of infection on the radial increment of spruce and pine was studied by measuring increment bores. Characteristics of the fungus in culture were studied using isolates obtained from each of the study plots. In some cases, the fungus was found to behave differently on spruce and pine. In pine, advanced necrosis of the cambium and phloem of the roots caused crown thinning and eventual standing mortality. In spruce, decay of the heartwood and inner xylem of the roots caused windfall of the tree, often before expression of noticeable crown symptoms. In both host species studied, spread was commonly observed from infected to healthy, contacting roots. Possible cases of spore inoculation through root wounds were also found. In all plots, pine showed a higher infection level than spruce. Subalpine fir (Abies lasiocarpa (Hook.) Nutt.) and Douglas-fir (Pseudotsuqa menziesii (Mirb.) Franco) present within the plots were not found to be infected. Infection by I. tomentosus was not found to reduce significantly the basal area increment in pine or spruce. The fungus in culture demonstrated a large amount of variation in growth rate, mycelium color and mat color and texture. Such variation occurred both within and among isolates, and could not be related to the host species from which the isolate was obtained. / Forestry, Faculty of / Graduate