Late Alfalfa Weevil Season For 2013

LEXINGTON, KY.
    Degreeday (dd) accumulations provide the best way to determine when to check fields for tip feeding by alfalfa weevil larvae. The first chance to see damage occurs when 190 dd (base 48 F) have accumulated starting on Jan 1.
   The table shows the differences in degreeday accumulations at 4 Kentucky weather stations through 31 March for 2011 through 2013. Alfalfa weevil egg hatch had begun at all locations by this time in 2011 and larval feeding was well along by now in 2012. We have yet to reach the 190 dd total this season at any of the locations.
   So far, low temperatures have delayed the start of the alfalfa weevil season. However, the pace can pick up rapidly if there is a sudden warming trend that stimulates egg hatch and rapid development of the insects.
   While we are coming off a cold winter, weevil eggs are hardy so there is no reason to think there will be a substantial winter kill to reduce populations. The cold spring should cause egg hatch to be pretty synchronized rather than being spread out over a longer time frame. If weevils are at damaging levels in fields, feeding should become apparent pretty quickly. The longer fields have been in production, the greater the chance for significant weevils populations. Δ
 DR. LEE TOWNSEND: Entomologist, University of Kentucky