–by Dr. Jeff Whitworth
Alfalfa weevil larvae continue to feed and thus increase in size (fig. 1). However, after monitoring several fields throughout north central Kansas over the last 10 days, there was not yet any field that had a 50% infestation level. (Infestation level determined by the stem count bucket method where individual stems are removed and quickly shaken into a 1 gallon white bucket to dislodge any weevil larvae that may be present. Then, count the number of larvae in the bucket and divide into the number of stems shaken into the bucket to get the percent infested stems). Alfalfa weevil monitoring should continue, however, as we are still relatively early and more larvae will probably be hatching.
Figure 1 Alfalfa weevil larvae and leaf damage (Cody Wyckoff)