Somewhere in Iowa this spring, alfalfa weevil populations will exceed economic thresholds and cause significant yield loss. Now is the time to be scouting alfalfa for this pest. I like to use a sweep net to simply determine if larvae have hatched in the field. Sweeping even a small patch of alfalfa with a net can reveal whether or not larvae are present. If no larvae are found, then move to the next field. However, if they are found in the net, the next step is the stem-sampling technique. This technique more accurately determines the population size and the potential for economic damage.
Iowa State University
Rice, Marlin E., "Alfalfa weevil--consider cutting as a management option" (2006). Integrated Crop Management News. 1238.
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