June 14, 2012

Figure 1. Mice can enter a structure through a hole as small as 1/4 inch. (Photo by Rex Baker) Figure 2. Deter rodents by removing weeds from around a storage structure and then adding crushed gravel to keep it weed-free. This will make it harder for rodents to hide and burrow beneath the bin. (Photo by Robert Timm) Rodent Management This is the second article in a three-part series. Also see: Part I. Potential Impacts of Rodents on Stored Grain Part III. Using Toxicants to Manage Rodent Damage to Stored Grain

Part II: Exclusion: A Non-toxic Way to Reduce Rodent Damage to Stored Grain

If rodents cannot access a structure, they cannot cause any damage. Though exclusion has the highest initial cost in terms of time and materials, those costs will seem inexpensive given the benefits that accrue year after year.

Seal Cracks and Crevices

Carefully inspect structures for cracks and crevices a quarter-inch in size or larger. Use sealants to secure gaps up to a ½ inch in diameter. For larger openings, such as gaps around pipes, use copper Stuf-fit or Xcluder™ mesh to fill the gap and follow up with a sealant appropriate for the surface.

Screen Passive Air Vents

Using ¼-inch hardware cloth is ideal, but galvanized ½-inch mesh also is effective. Be sure, however, that screens will not restrict airflow excessively.

Establish a Weed-free Zone

Pour ½-inch crushed gravel to a depth of 3 inches to create a 12- to 24-inch apron around the structure. The crushed gravel removes ground cover needed by rodents to hide from predators and hinders their burrowing.

Trim Tree Branches and Bushes

Sometimes rodents use trees, bushes, and other tall plants to gain access to structures. Ideally, tree branches should not be within 6 feet of the structure and shrubs should grow no higher than 4 feet of the roof’s edge.

Conclusion

For long-term rodent management, exclusion is the gold standard. Even if you are unable to implement all the strategies, we strongly suggest following as many as you can afford. Don’t forget that what you can’t do this year can be done in the next.

Resources

For more information on managing rodents and other crop pests, see UNL Extension NebGuides, including Rodent-Proof Construction—Structural (G1530).

Stephen Vantassel
Extension Wildlife Damage Coordinator
Scott Hygnstrom
Extension Vertebrate Pest Specialist