In the past few weeks, I have received several calls about how to control pocket gophers. Apparently, the lack of irrigation water and mild winter weather has provided gophers the opportunity to expand their burrow systems. These pests are very destructive to the alfalfa plants and harvest equipment. The following are some important facts about these pests.
• Pocket gophers prefer alfalfa. Pocket gophers reduce productivity of portions of alfalfa fields and native grasslands by 20 to 50 percent.
• Damage by pocket gophers can be reduced by exclusion, cultural methods and habitat modification, trapping, and toxicants applied by hand or with a burrow builder.
• Pocket gophers feed on roots they encounter from digging, from vegetation they pull into the tunnel from below, and vegetation above ground near the tunnel.
• Pocket gophers usually construct one to three mounds per day although the rate varies. One gopher brings about 2 1/4 tons of soil to the surface each year.
• Pocket gophers are consumed by owls, hawks, badgers, coyotes, foxes, bobcats, skunks, weasels, bull snakes and rattlesnakes.
Pocket gophers reduce the productivity of alfalfa fields and native grasslands on which they are found by 20 to 50 percent. If gophers are present on 10 percent of a field, they may reduce overall forage productivity of the field by 2 to 5 percent. Also, gopher mounds dull and plug sickle bars when harvesting hay or alfalfa. Gophers may at times, destroy underground utility cables and irrigation pipes.
Alfalfa varieties with several large roots rather than a single tap root suffer less when pocket gophers feed on them and are more resistant to grazing by grasshoppers. Each cut section of roots from a multi-rooted variety will send up a new shoot that may compensate for losses due to gophers.
Cultural practices such as rotating alfalfa with grain crops can effectively controls pocket gophers because annual grains do not produce large enough roots to support gophers year-round. Planting 50-foot-wide buffer strips of grain crops around a hay field can provide unsuitable habitat and minimize immigration of pocket gophers, if we had water to plant grain crops.
Habitat modification such as flood irrigation can effectively control gophers, especially in fields that are leveled to remove high spots that might serve as refuges. The wet-flooded soil generally prevents diffusion of air in and out of the burrows creating an inhospitable environment, if we had water to irrigate with.
Trapping is probably the best methods to reduce pocket gopher numbers on small to moderate-sized fields (less than 50 acres) and to remove remaining animals after a poison control program. Body-gripping traps (Death Clutch 1, Macabee, Victor, Guardian Gopher Trap), available from hardware and trapping supply stores, work exceptionally well for capturing gophers. Trapping usually is most successful in the spring and fall when gophers are actively building mounds. For more information on proper trap placement, you can watch a video produced by the University of California Cooperative Extension on “You Tube” at: https://www.youtube.com/watch?v=lGLGQigAYZI
There are four rodenticides registered for pocket gopher control:
• Strychnine (0.25 to 0.5 percent active ingredient),
• Zinc phosphide (2 percent active ingredient),
• Chlorophacinone (Rozol) (0.005 percent active ingredient), and
• Diphacinone (Eaton’s Answer)(0.005 percent active ingredient).
To poison pocket gophers, place the bait in their tunnel systems by hand or with a burrow builder machine.
Note: Strychnine Alkaloid Paste is a restricted use product for the control of pocket gophers, yellow-bellied marmots and ground squirrels. If you are interested in purchasing Strychnine Alkaloid
Paste, you can go to the Nevada Department of Agriculture’s website to access the order form, http://agri.nv.gov/Plant/Environmental_Services/Strychnine_Order_Form/
Zinc phosphide is also available for the control of vertebrate pests, please contact USDA APHIS Wildlife Services at 775- 851-4848 for more information.
Fumigants, such as aluminum phosphide and gas cartridges, are not very successful for controlling pocket gophers because the gophers either sense the poisonous gas and plug the tunnel, or the fumigants diffuse into the soil, particularly when it is dry. Pocket gophers reportedly can be controlled by injecting exhaust from an old vehicle without anti-pollution devices into the burrow for about 3 minutes.
A new method of control, “The Rodenator” involves injecting a mixture of oxygen and propane into the burrow system, then igniting it producing a concussive force that kills the pest.
The problem is all of these methods take additional monies and time. If we could only find a market for gopher fur coats or sell them for pets at the local pet store, we may have a solution to the gopher problem.
Source: W.F. Andelt and R.M. Case1 (5/06)