Alfalfa weevils feed on leaf tips and can cause extensive damage.
Alfalfa weevil damage isn’t likely to develop before most of Wisconsin’s first-crop alfalfa is cut – if it’s harvested within the first part of June, according to a late-May report on pests affecting alfalfa.
Many surveyed counties showed only one to four weevils per 100 sweeps, according to the Wisconsin Pest Bulletin. Hosted by the state ag department, it offers weekly seasonal reports from entomologists, weed specialists and plant pathologists.
Nevertheless, “regular sampling for larvae and leaf tip feeding should begin at this time and continue through harvest or until the weevil season has passed,” the bulletin authors write.
Other alfalfa pests being closely watched:
- Pea aphids. Their numbers are increasing, as shown by surveys conducted in the southern half of the state, from 30 per 100 sweeps scouted during the period of May 15-21 to 159 aphids per 100 sweeps the week of May 22-28.
- Meadow spittlebugs. Their first appearance was May 27 with a population average of less than two per 100 stems.
- Plant bugs: Counts are still low with these pests as well; they range from two to 28 bugs per 100 sweeps.