Establishing trees in existing pastures to create silvopasture could provide alternative income without sacrificing significant forage production. Factors such as grass species, tree species, competition for moisture and nutrients, and presence of fungal endophyte may affect tree growth. This study assessed whether three grass species, orchardgrass (Dactylis glomerata), tall fescue (Lolium arundinaceum), and Kentucky bluegrass (Poa pratensis) affected the growth of black walnut (Juglans nigra), northern red oak (Quercus rubra), and pitch x loblolly pine (Pinus rigida x taeda) differently. Four varieties of tall fescue were used that differed in Neotyphodium coenophialum endophyte status and growth habit (‘Ky-31' endophyte infected, ‘Ky-31' non-infected, Max-Q ‘Jesup' novel endophyte, and ‘Houndog V' turftype endophyte infected). Irrigation and/or fertilization were evaluated to determine if these practices would alleviate grass competition. Height and diameter growth of pitch x loblolly pine was unaffected by grass species but was increase by irrigation but not fertilization. Kentucky bluegrass appeared to be less competitive to black walnut or northern red oak than orchardgrass or tall fescue. Diameter growth of both tree species was significantly greater in Kentucky bluegrass than any other grass. Height growth of black walnut and red oak was greatest in Kentucky bluegrass and orchardgrass. Black walnut height growth in Kentucky bluegrass was significantly greater than that in ‘Houndog V' tall fescue only, while red oak height growth in Kentucky bluegrass was significantly greater than that in the four fescues. Endophyte status of tall fescue had no significant affect on growth of any of these tree species. Irrigation significantly increased the diameter growth of red oak and significantly reduced the height growth of black walnut.