Pocket gophers cause damages
Burrowing rodents like pocket gophers can damage fields, pastures and crops. When these critters move into barnyards or pastures, they may need to be exterminated or their numbers controlled.
Robert M. Timm, Ph.D. and Extension wildlife specialist emeritus at the University of California Hopland Research and Extension Center, says pocket gophers can have a serious impact on forage in fields and pastures.
These rodents can be a major problem in perennial plantings such as alfalfa, orchards and vineyards. Even on pasture and rangeland, gophers can reduce forage productivity, competing with livestock.
In a hayfield or crop, sometimes rodents’ mounds can damage the implements used for harvesting.
“This can be the case with pocket gophers in alfalfa or grain fields. The machinery may run into their mounds and be damaged, and their burrows sometimes interfere with flood irrigation. Water may go down the tunnels of ground squirrels or pocket gophers, rather than where it’s intended,” says Timm.
Rodent burrows can create erosion problems, especially on slopes, and can also damage ditches, irrigation canals and the integrity of earthen structures including roadways.
In the western U.S., there has been a lot of study involving these burrowing rodents’ damage to high-value agricultural crops, alfalfa or perennial plantings like orchards and vineyards.
They can also damage hayfields.
“The main control methods are trapping, rodent baits placed within the burrow system or fumigating the burrows,” Timm explains. “Historically, fumigation does not work well for pocket gophers, except for aluminum phosphide, which comes as a tablet or pellets that are placed within the sealed burrow.”
He continues, “This fumigant is highly restricted, however, and can only used by trained and licensed professionals. It can’t be used for rodent control in and around structures because there is risk that the phosphine gas generated could seep out through cracks in the ground or through the burrow system itself into structures that might be occupied by animals or people. It is fatal to anything that breathes it.”
Most other types of fumigants don’t work well for pocket gophers. They either smell it coming or sense that something is wrong and quickly wall up dirt to protect themselves.
Some producers hire pest control professionals who are licensed to use aluminum phosphide.
“In an orchard or vineyard, it might be worth hiring a professional to take care of the rodents. For producers who have perennial plantings – including trees or vines in full production – it is very expensive to lose them. Pocket gophers may girdle the root systems below ground, and we don’t even see that the plant is dead, until the next spring when it doesn’t green up,” he says.
Trapping works well if a person is diligent.
“This is something we learn by doing, and most people become adept at it with a bit of practice. There are a number of good pocket gopher traps on the market, and once producers learn to use them, they can be very effective,” Timm explains. “Ranchers who are trying to eliminate gophers or keep them from building up carry gopher traps around in their pickup.”
“As soon as they see a fresh mound, they try to trap that gopher before it reproduces or causes major damage,” he adds.
Trapping and using poison grain baits within the burrow system are the most common methods of control.
“Strychnine used to be the most effective and most readily available product to use, but it’s become hard to get. It is imported, and supplies are dwindling worldwide,” says Timm.
After using it for a number of years, however, it can become less effective.
Zinc phosphide and anticoagulant baits are also registered for pocket gopher control, but these are generally less effective.
“A few companies in the West are doing burrow fumigation for pocket gophers and ground squirrels using pressurized carbon monoxide machines,” Timm explains. “These devices use a four-cycle gasoline engine to produce carbon monoxide in the exhaust, which is piped into the intake of an air compressor driven by the engine.”
He adds, “The machines are expensive to purchase, so some producers simply hire operators of these machines to come treat rodent burrows with high-pressure carbon monoxide. Recent research indicates this technique may provide moderate to good success in killing pocket gophers, depending on the location, time of year, soil type and who is doing the operation.”
To achieve complete control may require a second treatment or follow-up using traps or rodenticide baits.
Heather Smith Thomas is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.