Pocket gophers, commonly known as gophers, are highly destructive pests that spend nearly all their lives underground. These small rodents feed primarily on the roots and fleshy parts of plants, causing significant damage to gardens, lawns, and agricultural fields. They also create extensive tunnel systems that can interfere with activities like mowing and damage underground structures such as irrigation lines. A single gopher can inflict costly damage, requiring a persistent, multi-faceted approach for management.
Understanding Gopher Activity and Damage
Identifying a gopher problem correctly is the first step in effective management, as their subterranean activity is often confused with that of moles or voles. The most distinct sign of a pocket gopher is the fresh dirt mound it creates while excavating its tunnel system. These mounds are typically fan-shaped or crescent-shaped, with a visible soil plug off to one side, marking the location of the plugged tunnel entrance.
This asymmetrical, plugged mound differs from the volcano-shaped, circular mounds created by moles, which have a centrally located plug. Gophers push coarse soil to the surface using their strong claws and teeth, while moles, which are insectivores, create finer-textured tailings. Gophers prefer moist, loose soil, and their mound-building is most noticeable during winter and spring in non-irrigated areas, though it occurs year-round in well-watered locations. Plant damage is noticeable when roots are severed or when whole plants are pulled below ground into the tunnels for feeding.
Exclusion Techniques: Creating Physical Barriers
The installation of physical barriers is the most reliable long-term method for protecting specific, high-value areas from gopher intrusion. These barriers prevent gophers from accessing the protected area through tunneling. The material of choice is galvanized steel hardware cloth or wire mesh, typically with openings no larger than one-half inch to three-quarters of an inch.
For protecting entire garden beds, the mesh should be installed vertically as a perimeter fence buried at least 24 inches deep. It is recommended that this barrier extend six inches above the soil line to prevent gophers from climbing over or gaining access from the surface. A successful installation often involves bending the buried portion of the wire outward at a 90-degree angle to create a six-inch horizontal barrier that discourages gophers from digging beneath the fence line.
Individual plants, trees, and shrubs can be protected at the time of planting using gopher baskets fashioned from the same galvanized wire mesh. These baskets must be large enough to allow for future root growth. When protecting mature tree trunks, cylinders of half-inch hardware cloth should be sunk approximately 12 inches underground and extend a foot above the surface to prevent gnawing on the bark. Using durable, galvanized wire is important because other materials rust and deteriorate quickly when buried.
Deterrents and Sensory Repellents
Non-lethal methods focus on making the protected area unappealing to gophers through sensory irritation or habitat modification. Many commercial repellents utilize castor oil as the active ingredient, working through a dual action of taste and smell. When applied, the oil penetrates the soil and contaminates the gopher’s food sources and the tunnel environment.
The ricinoleic acid in castor oil irritates the gopher’s digestive system, encouraging them to leave the treated area rather than forage there. Applying granular or liquid castor oil-based products requires watering them in to help the solution permeate the underground tunnels. To effectively drive the pests out, the product should be applied gradually, treating one section at a time to herd the gophers away.
Some individuals attempt to use vibrating or sonic spikes, but their effectiveness is inconsistent, as gophers may quickly become accustomed to the noise. Modifying the habitat can also reduce an area’s appeal by limiting the food supply and moisture. Reducing lush ground cover or limiting deep irrigation makes the soil less attractive for burrowing and foraging. Certain plants, such as the castor bean plant, are sometimes mentioned as deterrents, but they are highly toxic and unsuitable for most residential areas due to risks to pets and children.
Direct Population Control Methods
When gophers are already established, direct population control is necessary to reduce the number of pests creating damage. Trapping is a highly effective method, offering immediate results without the risk of secondary poisoning to other animals. Common traps include pincer-style traps like the Macabee or box traps, which are placed directly into the gopher’s main tunnel run.
To ensure success, the main tunnel must be located, typically by probing the ground near a fresh mound until the probe drops suddenly. Traps are then placed in pairs facing opposite directions within the opened tunnel, and the opening is covered to exclude light. The use of toxic baits, such as those containing strychnine or zinc phosphide, is another method to eliminate gophers. These chemical agents carry a high risk of poisoning non-target wildlife and pets, so they must be placed deep within the main burrow system and handled with extreme caution, often requiring professional application.