In contrast to last spring at this time, we've received a small number of reports on alfalfa weevil activity this spring. In fact, most reports indicate very few alfalfa weevils are out in fields. Nevertheless, the watch for alfalfa weevils should continue.
Figure 1 indicates the accumulated degree-days (base 48°F), from January 1 to April 21, 2003. Figure 2 projects the accumulated degree-days (base 48°F), from January 1 through May 6, 2003. The first peak of third-instar weevils occurs after the accumulation of 325 degree-days. Currently, the southern portion of Illinois has already reached that benchmark, and 325 degree-days will have accumulated in nearly all of Illinois by May 6. Remember, a second major peak of third-stage larvae occurs after the accumulation of 575 degree-days.
As degree-days continue to build, continue scouting fields for alfalfa weevils and symptoms of injury. We'll keep you posted on any developments.--Kelly Cook