Grazing sheep can be an effective, low-cost tool for controlling alfalfa weevils, Montana State University research reveals.
In a study on a commercial sheep operation, the researchers found that grazing reduced alfalfa weevil adult populations by 35-100% and weevil larvae numbers by 40-70%, depending on sampling date and study year.
They evaluated the use of sheep as an alternative solution for controlling alfalfa weevils, wheat stem sawflies and other pests in three studies funded by USDA’s Sustainable Agriculture Research and Education (SARE) program. Their findings and recommendations are outlined in a new SARE fact sheet, Sheep Grazing to Manage Crop Residues, Insects and Weeds in Northern Plains Grain and Alfalfa Systems. It also covers key details of animal selection, stocking rates, timing, economics and other issues.
“Arthropod pests alone cause an estimated $260 million in alfalfa damage each year across the U.S.,” SARE officials wrote in announcing the fact sheet. “Traditional control methods come with significant drawbacks: In many areas, stricter environmental regulations have led to bans on burning, and herbicide applications can be costly and management intensive.”
In addition to controlling pests, they pointed out that grazing provides an environmentally friendly alternative to pesticides, increases soil nutrient cycling from sheep waste deposited across the field, helps control erosion and lowers equipment and fossil-fuel costs through reduced tillage.
Using sheep as a management tool in cropping systems also benefits sheep producers by reducing feed costs and providing new business opportunities, they added.