UNL CropWatch May 18, 2010: Alfalfa Weevil Feeding Predicted

UNL CropWatch May 18, 2010: Alfalfa Weevil Feeding Predicted

 

 Map - Alfalfa Weevil Feeding Predicted

Figure 1.  Accumulated growing degree days since January 1, using a base of 48°F, to predict alfalfa weevil feeding. (Map developed by Al Dutcher, State Meteorologist, High Plains Climate Center)

May 18, 2010

Alfalfa weevil feeding is possible throughout Nebraska. Growers are encouraged to scout for signs of feeding damage and consider treatment where thresholds have been met. If the field has reached the bud or early bloom stage, immediate cutting is the most practical and efficient way to deal with a weevil problem.

Accumulated growing degree days (GDD), using a base of 48°F, can be used to help predict alfalfa weevil activity (Figure 1). Egg hatch begins at 300 degree days accumulated since January 1. Maximum damage will occur from about 450 to 600 GDDs. See the April 23 CropWatch story for scouting procedures, economic thresholds and control options for alfalfa weevil.

Bob Wright
Extension Entomologist, Lincoln