AgWatch

Alfalfa Growth May Outpace Weevil Damage

DR. LEE TOWNSEND

LEXINGTON, KY.
   Some tip feeding and a few small alfalfa weevil larvae were apparent in Fayette County alfalfa on May 4 (Figure 1).  However, plant growth in established alfalfa fields should be far enough along that it would take substantial numbers of weevils to cause significant damage. Continue to monitor fields because larvae are still small; but assess situations carefully before making an insecticide application.
   The cool, rainy spring has been ideal for aphid buildup in alfalfa. The pea aphid (Figure 2) is present in every field but rarely reaches damaging levels (50 or more per stem). While numbers drop off during the heat of summer, this aphid is present from April to November.
   Light to moderate populations provide a host or food source for beneficial wasps (Figure 3) and predators such as lady beetles. Unneeded insecticide applications can knock out beneficial insects. ∆
   DR. LEE TOWNSEND: Extension Entomologist, University of Kentucky



 


 
 Figure 1. Alfalfa weevil larva and tip feeding damage.
 Photos: Lee Townsend, UK













 Figure 2. Pea aphid.












 Figure 3. A small wasp will emerge from this swollen, tan, mummified pea aphid.

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