Winter Of 2013-14 Points To Later Alfalfa Weevil Season

   Contrasts in degree-day (dd) accumulations (base 48) from January 1 emphasize annual differences that can occur with alfalfa weevil activity. Adult weevils fly to alfalfa fields in the fall and remain there over the winter. If temperatures allow it, some egglaying can occur during the fall and into mild winters resulting in some early spring feeding damage by the larvae followed by a later peak. Earliest feeding can show up when degree-day accumulations reach 190. A cold winter and/or cool spring usually pushes that date back into about the 250 dd range. Our winter weather and current dd accumulations point to a late weevil season this spring. In contrast, the dd accumulations in Table 1 show a weevil season that was largely over by this date in 2012.

Table 1. Degree-day accumulations from the UK Ag Weather Center as of March 23 of the year  

You can check on dd accumulations for several pest insects, including the alfalfa weevil, at this Web site. Information using degree-day accumulations and assessing alfalfa weevil populations are available at∆
   DR. LEE TOWNSEND: Extension Entomologist, University of Kentucky

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