Weather and disease records from the Blackland Research Center, Temple, TX were analyzed from 1969 through 1982 to correlate the progression of Phymatotrichum root rot with prevailing weather conditions. During the 14-year period, there were five years in excess of 40 inches of rainfall. The mean percentage of root rot was 82%, which was 49% above the 14-year mean of 55%. The five dry years had 29% root rot, and 29 inches of rainfall with very little occurring in June and July. The mean annual temperature was 66.3 F for the 14-year period. The wet years had a mean temperature of 65.1 F and the dry years had 67.4 F. There were 82 days above 90 F of which 17 were over 100 F during the dry years. This compared to 64 days above 90 F with only two days over 100 F in the wet years. Disease progression followed a compound interest curve during the wet years, and a simple interest curve during dry years.