Abstract: Rhizoctonia-induced root diseases can significantly affect wheat and peanut production where these two field crops are grown in rotation. Hence, this study characterized two isolates of Rhizoctonia sp. from wheat [R. cerealis (RC) and R. solani (RSW)] and one from peanut [R. solani (RSP) ] for cultural traits and pathogenicity on Hard Red Winter Wheat (HRWW). The RSP had a higher optimum temperature than RC and RSW for growth (hyphal extension) on media (25 to 27.5°C versus 20 to 25°C), seedling emergence, shoot and root weight and disease severity (≥25°C versus <25°C). Of six HRWW cultivars tested, TAM 101, Tonkawa and Custer demonstrated some resistance to RSP at 30°C. Field trials revealed that RC and RSW significantly reduced seedling emergence in late-planted wheat when soil temperature was cool (<27°C), but did not reduce seedling emergence in early-planted wheat when soil temperature was high (>35°C). In contrast, RSP significantly reduced seedling emergence in both early and late-planted wheat and also reduced forage production in early-planted wheat in fumigated soil. Results suggest that Rhizoctonia from peanut (a warm weather crop) are more virulent on wheat at higher soil temperatures associated with early planting, whereas Rhizoctonia obtained from wheat (a cool weather crop) are more pathogenic on wheat at lower soil temperatures associated with late planting. Hence, soil temperature as affected by planting date should be considered in areas where wheat is planted following peanut if root disease caused by Rhizoctonia sp. is a concern.