Seeding year alfalfa is just getting its "field legs" and needs to be managed differently than established alfalfa. Stems are spindly, roots are small and growth is slower. Following these harvest guidelines can help assure multiple harvests and a strong first season.
High populations of alfalfa weevils have been found in alfalfa throughout the Nebraska Panhandle; lower populations were reported this week in central and eastern Nebraska. The economics would warrant continued scouting through June to provide for timely treatment, if necessary, and yield protection.
If high quality hay is your goal, don't delay harvest. However, if you're looking to rebuild your hay supply, letting it grow almost until bloom will provide more feed while using water resources more efficiently.