May 23, 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 9 CropWatch discussed scouting procedures, economic thresholds and control options for alfalfa weevil. (Maps developed by Al Dutcher, State Meteorologist, High Plains Climate Center).

Figure 2. Accumulated growing degrees through May 26. Continue scouting for signs of feeding damage and treat, based on thresholds in the May 9, 2008 CropWatch. (Maps developed by Al Dutcher, State Meteorologist, High Plains Climate Center).

Figure 1. Accumulated growing degrees through May 19. Alfalfa weevil egg hatch has occurred across much of the state and field scouting should be underway.