An unparalleled outbreak of red oak borer, Enaphalodes rufulus (Haldeman), has been implicated as the major contributing factor to oak mortality coincident with an oak decline event in the Ozark National Forest of Arkansas. Armillaria, a root rot fungus, has contributed to oak mortality in other previous oak decline events. No documented evidence is available for Armillaria’s occurrence in the Arkansas Ozarks. Molecular diagnostic techniques were used to identify species of Armillaria present in this area. Armillaria mellea, A. gallica, and A. tabescens were positively identified from three different landforms; south and west facing slopes and ridgelines. Measures were taken to identify relationships between red oak borer abundance and presence/absence of Armillaria on these landforms. Armillaria was less frequent on ridges than either south or west slopes. Red oak borer within-tree density is greatest on ridges, suggesting more red oak borers are needed for tree death when Armillaria is not present.