The Plant Pathology Department at North Dakota State University (NDSU) is providing a potato blightline service at no charge. This is the 13th year that this service has been provided.

The hotline uses local weather data collected from weather stations throughout the area to forecast the occurrence and spread of late blight in 14 nonirrigated and nine irrigated production areas in North Dakota and western Minnesota. The data is processed by the North Dakota Agricultural Weather Network (NDAWN) and analyzed by a computer program to forecast when conditions are favorable for late blight to occur.

The forecast information is used by Gary Secor and Neil Gudmestad, NDSU plant pathologists, to make late blight management and fungicide recommendations. The recommendations are made Monday, Wednesday and Friday of each week during the growing season.

The hotline will continue through mid-September, depending on disease pressure. The hotline also will be used to confirm late blight infection and serve as a clearinghouse for national late blight information.

In addition to late blight forecasting, the hotline provides cumulative P-values for early blight disease forecasting and management recommendations. It also serves to alert growers of other disease and insect news, as well as posting messages of general interest, such as potato field day dates.

The NDAWN Web site for potato disease forecasting contains colored maps to illustrate the late blight severity values (both two-day and seasonal), favorable day values and P-day values for early blight.

Growers and scouts are encouraged to send suspected late blight samples for positive identification. Leaf samples should be placed in a slightly inflated plastic resealable storage bag without a wet towel and sent to Gary Secor, NDSU Walster Hall, Room 306, Fargo, ND 58105.