Experiments were conducted in 1992, 1993, and 1994 to determine the effects of surface residue on incidence of Cylindrocladium black rot (CBR), Sclerotinia blight, and Southern stem rot of peanut in microplots in North Carolina. Soil was infested with either Cylindrocladium parasiticum, Sclerotium rolfsii, or Sclerotinia minor and plots were planted with the peanut cultivars NC 7 or NC 10C. Wheat straw was applied to establish 80 to 90% soil-surface coverage. Disease incidence data were collected every 2 weeks in 1992 and weekly in 1993 and 1994. Southern stem rot incidence did not increase with straw amendment but final inoculum density of Sclerotium rolfsii was highest in straw-amended plots. Straw amendment enhanced CBR incidence in 1992, but had minimal effects in 1993 and 1994. Neither root rot severity nor inoculum density of C. parasiticum was affected by straw treatment. Straw application reduced Sclerotinia blight in 1992 and 1993 but not in 1994 compared with unamended plots. Initial inoculum density had the greatest impact on final Sclerotinia minor populations. Soil temperature and moisture were monitored in 1993 and 1994. Soil at 0 to 2 cm of depth in strawamended microplots was 1 to 2°C cooler than in unamended plots.