July 17, 2008

Daily Cercospora leaf spot alerts are now available on the Web for sugar beet growers and others.

Updates are linked from UNL's Panhandle Research and Extension Center's site at http://www.panhandle.unl.edu.

The prediction system is an estimate of the potential for disease development based on the relative humidity and temperature measured within fields at 10 sites in Nebraska, Colorado and Wyoming. In addition to the Web site, the disease alerts also are shared via media outlets, consultants, and growers.

UNL Plant Pathologist Dr. Bob Harveson said growers should use the information as a guide to local environmental conditions, and potential for disease development in their fields. Because of the high degree of variability between and within fields, Harveson said, the system requires that growers inspect their own fields prior to making fungicide applications.

Cercospora leaf spot (CLS) is the most serious and destructive leaf disease of sugar beets in western Nebraska, northeastern Colorado, and southeastern Wyoming. It is caused by the airborne fungus Cercospora beticola.

Development of the disease depends highly on environmental conditions, characterized by periods of high humidity or extended leaf wetness (longer than 11 hours) and warm temperatures (above 60°F at night and 80-90°F during the day). For this reason, it is quite possible to predict when outbreaks will most likely occur. In the dry climate of western Nebraska, these conditions are most common in late summer under irrigation.

The Cercospora Alert Forecasting System was started in the late 1980s by two scientists in the Institute of Agriculture and Natural Resources, Albert Weiss and Eric Kerr. Today the region-wide system is carried on through the joint efforts of the plant pathology program at the Panhandle Research and Extension Center, the agricultural staff of the Western Sugar Co-op, and several crop consulting services.

David Ostdiek
Extension Communication Specialist
Panhandle REC, Scottsbluff