–by Anthony Zukoff — Southwest Research Extension Center
In the southwest region near Garden City, several alfalfa fields checked on March 31 (344 accumulated degree days) had active 1st instar weevil larvae. Damage to the plants was not very apparent yet, but light pin-holing could be found. Warm weather in the high 80’s is forecast for the area this weekend which likely will give the weevils and alfalfa a boost. The alfalfa in the area is about 4 inches tall right now. Remember, for 3 to 7-inch-tall alfalfa, treat when feeding is evident on the top inch of growth (1-2 larvae per stem); retreatment may be necessary before cutting. Pea aphids were also present in these fields at low levels. Light populations of aphids in the field can help boost the number of beneficial insects, such as ladybugs, which will migrate from the alfalfa into other nearby crops later in the season. If predators and parasitoids are not apparent, treatment may be needed if there are 50 aphids per stem in 10 inch tall alfalfa.
Weevil pinhole
Weevil Pea aphids