We have received several reports of aphids and alfalfa weevil in Nebraska alfalfa prior to first cutting. No aphid samples have been submitted to us for identification, but the most common early season aphid species are pea aphids. Tom Hunt reports that spotted alfalfa aphids are being detected in the suction trap maintained at UNL’s Haskell Agricultural Laboratory near Concord.
Several species of aphids may occur in Nebraska alfalfa. There are four aphids commonly seen in Nebraska alfalfa — pea aphid, spotted alfalfa, blue alfalfa aphid and cowpea aphid. They differ in their seasonal occurrence and damage potential.
An article by Iowa State University Extension Entomologist Erin Hodgson summarizes life cycles and identification of these four aphids.
| Alfalfa growth stage | Pea aphid/Cowpea aphid | Blue alfalfa aphid/Spotted alfalfa aphid |
|---|---|---|
| Seedling | 5 per stem | 1 per stem |
| 40 per stem | 10 per stem | |
| 10-20" | 75 per stem | 30 per stem |
| >20" | 100 per stem | 50/100 per stem |
Insecticide options for Nebraska alfalfa can be found in 2023 Guide for Weed, Disease, And Insect Management, Nebraska Extension Circular 130.
Potato leafhoppers have the potential to injure alfalfa in Nebraska every year. They have been reported at UNL’s Eastern Nebraska Research, Extension and Education Center and in South Dakota this June. They don't overwinter in Nebraska but rather are brought in on southerly winds. Generally, they are a second and third cutting pest. If you have not yet started to scout for potato leafhopper, now would be a good time to begin.
For treatment guidelines and control options, see this CropWatch article.
