May 16, 2008

Accumulated growing degree days (GDD), using a base of 48°F, can be used to help predict alfalfa weevil activity. Egg hatch begins at 300 degree days accumulated since January 1. Maximum damage will occur from about 450 to 600 GDDs. The May 2 CropWatch discussed scouting procedures, economic thresholds and control options for alfalfa weevil. (Maps developed by Al Dutcher, State Meteorologist, High Plains Climate Center).

Figure 1. The accumulated growing degrees indicate that alfalfa weevil egg hatch should have occurred across much of Nebraska and feeding is likely along the southern counties. (Maps developed by Al Dutcher, State Meteorologist, High Plains Climate Center).