By Scout Nelson
The University of Minnesota Extension's May 28 Strategic Farming: Field Notes session focused on alfalfa and pasture health. It covered alfalfa pest concerns, crop status, and pasture management strategies.
Despite some snow cover in northern Minnesota, many alfalfa fields have faced winter damage. Limited snow during cold periods caused winter kill, especially in older fields. Growers are encouraged to check stand health and adjust accordingly.
Alfalfa weevil, a common pest, overwinters as an adult and lays eggs in stems. Larvae cause damage by feeding on leaves, which can reduce crop quality. While recent numbers in west-central Minnesota have been low, risk remains as more larvae hatch. Degree-day models forecast pupation in parts of Iowa and Minnesota.
Effective scouting includes shaking plants into a bucket instead of using sweep nets. Early mowing can kill larvae, though some may hide under windrows. Treatment depends on crop height, pest numbers, and market prices.
Insecticide options are limited. Chlorpyrifos products registered for 2025 can be used until June 30. However, older versions or unregistered brands like Lorsban cannot be applied this year. If pyrethroid resistance is suspected, contact UMN Extension for sample collection.
Other pests like pea aphids and potato leafhoppers were mentioned. Pea aphids are present but not at harmful levels yet. Potato leafhoppers may become a concern later, especially in stressed crops.
Pastures have been slow to regrow this season. Light-green grass may indicate a nitrogen deficiency. Applying nitrogen, managing harvest times, and using nurse crops like oats can help improve pasture health and productivity.
For more pest scouting details, see “Alfalfa insects: What to look for and how to scout.” For pasture tips, visit “Grazing and pasture management for cattle.”
Photo Credit:university-of-minnesota
Categories: Minnesota, Crops, Alfalfa