Protecting fruit trees from disease and insect pests is an essential part of an agriculture production system. The classes of insecticides and fungicides used in apple production have evolved rapidly, but the application techniques have changed very little in the last fifty years, creating many ecological, environmental, and health issues. One application method that arborists use commercially, and is of growing interest to agriculturalists is trunk injection. Trunk injection is an environmentally sensitive application technique which was used in this research to apply insecticides and fungicides systemically into Empire apple trees (Malus domestica Borkhausen) and semi dwarf MacIntosh (RedMax) at the Michigan State University (MSU) Trevor Nichols Research Center (TNRC) in the growing seasons of 2010 and 2011. The insecticides studied included Imidacloprid (Ima-jetTM), rynaxypyr (XCL-r8TM), and emamectin benzoate (TREE-ageTM). The fungicides used were propiconazole (Alamo®), phosphorous acid (Phospho-jetᵀᴹ), and a diluted solution of penthiopyrad (FontelisTM). These compounds are currently formulated for trunk injection and were tested to control the main insect pests and disease of apples. Insect and fungal control along with injury experiments were measured using field studies, laboratory bioassays, and residue profiling of a range of apple tree tissue types. Trunk injection may provide substantial persistence in the vascular system up to 2 seasons, minimizing many off-target effects, but also may cause significant injury to the tree.
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