Ectomycorrhizal Fungus Inoculations of Established Residential Trees

"Trees growing in forest soils have abundant mycorrhizae. This association increases nutrient and water absorption, increase tolerance to stresses, decreases root disease and is, therefore, important in maintenance of forest health and vigor. Certain species of ectomycorrhizae improve survival and growth of pine and oak seedlings on clear-cut reforestation sites, on forestation sites in the tropics, and on adverse sites, such as coal mined lands and borrow pits. The application of mycorrhizal technology in forestry and mine reclamation is at the commercial level. Recently, a preliminary study showed that the fine roots and ectomycorrhizal development were significantly increased by inoculation with spores of Pisolithus tinctorius (Pt) on 25 to 46 cm caliper (10 to 18 in.) northern red oak (Quercus rubra) trees growing on a man-made landscape in Michigan. There is an obvious need to further test the application of mycorrhizal fungi on established landscape trees. The purpose of this project was to determine if inoculations with spores of Pt alone or in combination with slow release nitrogen fertilizer, would improve the density or development of fine roots and ectomycorrhizae on established residential trees. A secondary goal was to determine if there was significant supplantation of the naturally- occurring ectomycorrhizae on treated trees."