From June 1 to September 1, a summary of the conditions that favor late blight are presented in graphic form for two locations in the state (Forest River and Grand Forks). Late blight has been present in this growing region for the past 10 years (1992 - 2001). From these figures, it is apparent that conditions (low relative humidity and moderate temperature) for the development of late blight (expressed as cumulative disease severity values) in 1999 were less conducive than conditions experienced between 1992-1995 but more conducive than the period of 1996-1998. The 1999 growing season was particularly conducive in some areas, such as Forest River, during the month of August where significant increases in cumulative disease severity values occured due to late season rains.

Severity values in Forest River during the 2000 growing season were comparable to those seen from 1992 to 1995, and higher than those seen in 1996-1999. In Grand Forks the severity values were the highest seen since the study was initiated in 1992. Despite the favorable weather throughout the region, little late blight developed this year. This indicates that growers are doing an excellent job protecting fields from late blight under highly favorable conditions.

Forest River	Grand Forks