- Author: Niamh M Quinn
- Author: Roger A Baldwin
- Author: Carolyn Whitesell
Pocket gophers can cause significant damage to valuable turf, girdle trees, and chew irrigation lines. Their mounds can create tripping hazards and lead to erosion concerns when found on slopes. Luckily there are multiple successful management options to choose from when it comes to managing pocket gophers.
Do I have a pocket gopher?
Pocket gophers are small burrowing rodents that are often identified from the damage they cause rather than a sighting of the animal itself. Pocket gophers spend most of their time below the surface and while it is possible to see them above the ground, or peeping out of a burrow (Figure 1), the easiest way to determine the presence of pocket gophers is by the crescent-shaped mounds they leave behind on the surface from excavating their burrows. Pocket gopher mounds can be differentiated from mole mounds by their shape—mole mounds will be round whereas pocket gopher mounds have the distinctive crescent shape. Pocket gophers do not hibernate and are active year-round, so it is important to be vigilant when managing pocket gophers.
Management options
There are many management options for pocket gopher control and in California, significant research has been conducted to better utilize and examine the effectiveness of many of these tools. While there continues to be restrictions on some of the toxic options for pocket gopher management, there are still multiple non-chemical options to choose from that fit well into an IPM plan. Pocket gopher trapping has proven to be one of these very effective methods.
Trapping
Trapping is an excellent option for managing pocket gophers, even if you think you have a large population. In general, there is only one pocket gopher per tunnel system, so once you have captured one, you can move to the next system. Be aware that during the breeding season, there could be both a male and female in the burrow system, and after the female gives birth and the pups are dispersing, you can find the pups in the burrow system with reproducing females. In these scenarios, you might capture more than one pocket gopher per trap set.
Trapping takes longer when compared to toxic bait application or burrow fumigation with aluminum phosphide but it can be highly effective when done correctly.
Make sure you have the right tools when it comes to trapping pocket gophers. It is important to have sufficient traps for the population you are dealing with. Focus trapping efforts on fresh mounds, as older mounds are less likely to be active. If you are unsure what mounds are active, you can knock over all mounds and trap at the new mounds that appear. Pocket gophers may not mound every day, so trap over more than one day to be successful. It is worth noting that it can be difficult to determine individual burrow systems from each other. Some practice is required to better define which mounds are likely from the same individual. If a trap set is not successful after 1 or 2 days, move it to a new tunnel location.
Trap selection (Figure 2) and placement may be important when choosing trapping as your pocket gopher control method. In studies, the Gophinator trap caught larger pocket gophers at a higher rate than the Macacbee trap. In addition, these traps often require larger excavations in the soil. For areas like high value turf, these traps may not the best option. An alternative trap is one resembling the GopherHawk, which may cause less damage because they don't require as large of an excavation in the soil.
When you set a pincher-style trap like the Macabee or the Gophinator, or a box-type trap like the Black Box or Black Hole, it is important to locate the main run of the burrow system. To do this, take a long metal rod like a screwdriver and probe around the mound. You will need to stick your probe into the ground at depths of about 4 to 12 inches. When you find the tunnel, you will experience a sudden drop in resistance. This skill is difficult to acquire but will improve with practice. Once you have located the main run, you need to excavate an opening in the tunnel to allow for setting of the trap. You can use a hori-hori knife or a trowel to make this hole, which may need to be more or less extensive depending on which style trap you choose.
If you are using a pincher-style trap that is set inside the tunnel, make sure that the tunnel you are setting the trap in is straight. You can check this by putting your excavator tool into the tunnel and making sure that at least 6 inches of it fits into the tunnel. This way you know the tunnel doesn't turn; tunnels with turns often allow the pocket gopher to bypass the jaws when activating the trap, thereby resulting in triggered traps that miss the gopher.
Several attractants have been tested but they did not influence visitation or capture rates of pocket gophers to traps. Attractants also did not influence the gender of pocket gophers captured. There is no impact of human scent on the success of trapping pocket gophers.
Is blocking light by covering trap sets necessary when trapping for pocket gophers? Covering and uncovering pocket gopher trap sets is time consuming and does not result in a greater number of captures. However, if you are trapping in areas with high foot traffic, there may be some benefits to covering your trap sets. You can cover the traps with sod, landscape cloth, or something like cardboard or plywood to prevent people or pets from interfering with your trap sets. In general, it is recommended that you cover sets when using box traps, since pocket gophers will likely plug tunnels before hitting the trigger wire of these traps if you leave them uncovered.
It can be helpful to tie a flag to the traps so you can easily remember where they were set. This can also help you recover the trap if the gopher drags it away.
When you recover a dead pocket gopher, remove it from the trap, put the gopher back in the tunnel, and cover it up. You can also double bag the animal and place it in the trash. Always wear gloves when handling pocket gopher or any other wildlife carcasses.
Toxic baits
There are several options for pocket gopher management using toxic baits. It is important to ensure that bait is placed correctly in the tunnel either by using a probe with a bait applicator or by hand using a funnel and spoon. Always read and follow the label. Many toxic baits that are used to manage pocket gophers require a restricted materials permit. However, there may be exemptions for products applied for structural pest control, industrial use, and institutional use.
Strychnine is the most effective type of bait used for pocket gopher management. This toxicant is an acute rodenticide where a lethal dose can be acquired after a single feed. Pocket gophers can develop behavioral resistance to strychnine. This enables pocket gophers to consume what is normally more than the lethal amount by periodically eating sublethal amounts. Pocket gophers also can be physiologically tolerant to strychnine since after they ingest a series of higher doses of strychnine, they can tolerate increasingly higher doses of it. It is important to rotate strychnine in with other management tools to avoid this type of resistance.
Zinc phosphide is also an acute rodenticide that is lethal after a single feeding. Bait shyness or taste aversion can be associated with this management option. Because of this, zinc phosphide may not perform as well as strychnine.
First generation anticoagulant rodenticides, including chlorophacinone and diphacinone, are multiple-feeding anticoagulants that are less toxic than strychnine and zinc phosphide. Since these baits require multiple feedings over 3-5 days, it is important to make sure that there is a continuous supply of bait during your treatment period.
Fumigation
Aluminum phosphide is highly effective, especially in moist soils. However, aluminum phosphide is a highly restricted material. It must be applied by a certified applicator, or the application must be supervised by a qualified applicator. You must have a restricted materials permit, a written recommendation to apply on production or non-production agricultural sites, and a Notice of Intent (NOI) from your local Agricultural Commissioner. You are also required to have a Fumigation Management Plan. You are not permitted to apply this product within 100 feet of a potentially occupied structure. The only place on school grounds where it is permitted to apply this product is on athletic fields.
Gas cartridges are not effective because pocket gophers seal off their burrow when they detect the smoke.
Carbon monoxide producing machines and carbon dioxide are registered for use in California against burrowing rodents. Carbon monoxide producing machines are registered devices, while carbon dioxide used for rodent control is considered a registered pesticide.
Carbon monoxide devices generate carbon monoxide which fills the burrow system and asphyxiates the pocket gopher. These devices include the BurrowRx, Cheetah Rodent Controller, CO Jack, and Pressurized Exhaust Rodent Controller (PERC) Machine. Research has shown that the PERC machine can be moderately effective at managing pocket gopher populations. Its efficacy increases in moist soil conditions. Some of these devices are more suited for urban applications and some for larger scale production agriculture. You are not permitted to use a carbon monoxide pest control device within 100 feet of a structure inhabited by people or domestic animals, whether occupied or not.
Carbon dioxide gas is a pesticide that is registered for use on several sites that include production agriculture, non-production agricultural sites, and residential areas. There are no distance restrictions for the application of this pesticide. It is important to follow the label. Solid carbon dioxide (dry ice) is not registered for use on pocket gophers.
Natural predators
Vertebrate predators—including owls, snakes, cats, dogs, and coyotes—eat pocket gophers. However, they will rarely control all pocket gophers in an area. Predators rarely remove every prey animal but instead move on to hunt in areas with more prey. In addition, pocket gophers have defenses against predators. For example, pocket gophers can evade snakes in their burrows by pushing up an earthen plug to block the snake's advance. Relying solely on natural predators might not control pocket gophers to the desired level. Research has shown that pocket gophers appear to be an important prey animal for barn owls nesting in perennial crops, and thus barn owls may be able to provide some pest control services in those areas.
Exclusion
Exclusion can be difficult and expensive for pocket gopher management, but it may be justified if you are trying to protect individual or high-value landscape plants. You can use hardware cloth (1/2-3/4-inch mesh) buried at least 2 foot deep with an additional 6 inches of hardware cloth bent at a 90° angle. You should also extend fences at least 1 foot above the ground because pocket gophers may move above ground to access the planting you are trying to protect. There are wire baskets available to protect individual plants or bulbs from pocket gophers. These baskets can also be fashioned from chicken wire. Remember that it is important not to restrict the growth of the plant inside the basket, so ensure the wire basket is large enough to accommodate the adult plant's root structure.
For more information about pocket gopher management, see the UC IPM Pest Notes: Pocket Gophers.
[Originally featured in the Spring 2024 edition of the Green Bulletin Newsletter for structural and landscape pest professionals.]
- Author: Ben Faber
by UC ANR Staff Writer
Publication helps growers identify the rodent species on their properties, their life cycles and tools available to control them
Burrowing rodents can cause extensive and expensive damage to orchards and crop fields. To manage the pests without chemicals used on conventional farms, organic growers can consult a new publication from UC Agriculture and Natural Resources scientists.
“Burrowing Rodents: Developing a Management Plan for Organic Agriculture in California” outlines management within organically acceptable methods using an integrated pest management approach.
California ground squirrels, pocket gophers and meadow voles are the three most common species that cause damage. Squirrels chew on seedlings, fruit and nuts, killing young trees and reducing crop yields. In addition to plants, ground squirrels, pocket gophers and voles can chew on irrigation lines, and their burrow systems can channel water away from plants and erode the soil. The holes and mounds created by burrowing rodents pose hazards to farmworkers and farm machinery.
This publication helps growers identify the rodent species on their properties, their life cycles and tools available to control them.
“Growers can read about how to effectively select and set a range of traps for burrowing rodents,” said co-author Margaret Lloyd, UC Cooperative Extension small farms advisor for the Capitol Corridor. “Traps are an important tool for organic management, but maximizing control comes from integrating knowledge. Here we present information about rodent biology, trap efficacy, biocontrol, habitat management, plant protection and other approaches to collectively manage the pest problem.”
In the publication, Lloyd and Roger Baldwin, UC Cooperative Extension wildlife specialist in the UC Davis Department of Wildlife, Fish and Conservation Biology, review the effectiveness of commercially available traps – where to place the traps, whether to use attractants, and methods of euthanizing the animals.
They also offer cultural techniques for deterring rodents such as flooding fields and deep ripping soil to destroy burrow systems. Crops for orchard floors or cover cropping can be selected and managed to minimize habitat that protects and encourages gophers and voles.
For biological control, they suggest barn owls, raptors and snakes might be able to assist, but warn growers that predators alone will not be able to eat enough of the rodents to reduce the high populations to tolerable levels for many growers.
“Effective management will rely on a suite of tools,” said Baldwin.
The 15-page publication is available for free download at https://anrcatalog.ucanr.edu/Details.aspx?itemNo=8688.
- Author: Anne Schellman
In California, we can't rely on Phil. Instead, we have gophers which are active all year. This makes them an unreliable source of information about the start of spring, since they are constantly popping up out of their burrows. Incidentally, spring officially starts on March 20 this year.
For gardeners, the presence of gophers can be frustrating. Most can tolerate a few insects on plants, or a small patch of a disease that can be cut off. However, just one gopher can consume an entire vegetable garden or dig multiple holes in the lawn and landscape in a short amount of time.
What made the holes in my garden or landscape?
If you see a hole, it might be a gopher or a mole. Gophers digging in lawns and landscapes leave holes that look like the photo to the right. Typically, they are crescent or horseshoe in shape. As they dig tunnels, gophers move fresh soil to the surface. You can usually see a plugged hole next to the mound.
Moles are another burrowing animal that also create mounds. However, their mounds are more circular, as shown in the photo in this post.
To learn more about gophers and how to control them, visit the UC IPM Pest Notes: Pocket Gophers.
If you suspect the holes in your landscape or garden are made by another animal, read the UC IPM Pest Notes: Ground Squirrels.
/h4>- Author: Ben Faber
Burrowing Rodents: Developing a
Management Plan
for Organic Agriculture in CA
RELATED ITEMS
- California ground squirrels Otospermophilus spp.
- Pocket Gophers Thomomys spp.
- Meadow voles Microtus spp.
This free publication is available by download.
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It's an exasperating experience. You go to the nursery, pick out a flowering plant, shrub, or tree and bring it home only to have some critter damage or destroy it within the first week. Pests cause damage and waste time and money. The most common pests in the home landscape and garden are voles, moles, and gophers. By knowing what you're dealing with, it will be easier to eradicate the problem.
Voles. Also referred to as field or meadow mice, voles are small rodents three to nine inches in size (depending upon the species). They look a lot like hamsters, which are their close relatives. Damage done by voles is often mistaken for that of gophers. Voles are herbivores; they can gnaw on the bark of trees and shrubs, or simply eat the roots. They will also eat the tops of new vegetable transplants, leaving behind damage similar to deer nibbling. If you look closely, you'll see the vole's teeth marks on the stalk of the plant.
Voles are active both day and night and do not hibernate. They are shy creatures and build complex tunnels under dense ground cover such as lawns, grasses, and meadows. They live in colonies, spending most of their lives underground. Voles have an extremely short life cycle, living just three to six months, but females can become pregnant at three weeks old. The gestation period for female voles is sixteen to twenty-four days. A typical litter is five to eight baby voles. Young voles become self-sufficient after several days, at which time the mother vole moves on to find another partner to mate with. Because of their rapid reproductive rate, one mating vole pair can be responsible for producing one hundred voles (offspring, offspring of offspring, you get the picture) in a year. Even a single pair of voles can rapidly become a vole kingdom.
If you don't take measures to control voles when you first notice evidence of their presence, they can quickly create a problem that spirals out of control. Signs of vole infestation include holes with a surface diameter of around one and a half inches close to their surface runways (raised ground on top of their tunnels). Damage to the roots of trees, yellowed and wilting plants, missing bulbs, teeth marks around the bottom of trees and shrubs, and irregular paths of one to two inches of trampled grass or soil are also signs of vole infestation.
Modifying the habitat can be effective in controlling vole populations. Keeping the yard cleared of dense vegetation, any lawn mown, and shrub branches trimmed up off the ground can deter voles. Circling tree trunks with guard mesh is also helpful. Voles often thrive underneath weed cloth put down to prevent weeds from growing around ornamentals, and beneath mulch used to keep plant roots cool in the summer. Removing both is a deterrent tactic. It is also helpful to remove bird feeders, or control birdseed spillage. Keeping birdseed off the ground reduces food for voles.
Exclusion, repellants, and traps are more effective means of controlling voles. Hardware cloth (with one-quarter inch or smaller mesh) can be a useful barrier. The cloth can be fashioned into a fence at least twelve inches high and buried three inches in the ground to surround flower beds. Baskets can be made or purchased to protect trees and shrubs. Because coyote and fox urines are stressful to voles, application encourages them to move on. Coyote urine and fox urine can be purchased online. Repellants containing capsaicin (and active component of chili peppers) and thiram (a fungicide) have also proved to be effective on ornamental plants, but remember that repellants often wash away with rain and need to be reapplied. Although bait is not required, peanut butter mixed with oatmeal can be smeared on trap triggers when using mouse traps to eradicate voles. Two to three traps need to be set by each hole or runway. Baited traps need to be covered with a box or PVC pipe to deter other critters such as birds and squirrels. Make sure the box has a one-inch hole cut out in order to allow the vole to reach the trap.
Moles. While there is only a one-letter difference between moles and voles, that's where the similarities stop. Moles are five to seven inches long and have long, fleshy noses which serve as touch organs. The feet, nose, and tail of a mole are pink. Moles have no external ears. Their eyes are buried in their fur, and their broad front feet are equipped with super-sharp claws for digging. Moles are mammals, not rodents, eating worms, ants, and grubs (certain beetle larvae). Many people attempt to control moles by eliminating their food source, but this has proved to be a difficult strategy because of a mole's varied diet. Eliminating grubs in a lawn will only lead moles to turn to earthworms in garden beds. But earthworms are good for our soil and leave behind beneficial castings.
Moles live entirely underground and can tunnel one foot per minute, creating extensive tunnels and volcanic-shaped mounds when breaking ground. A mole's damage to a lawn or plant is accidental since they, unlike voles, don't eat plants. Most of the time, a mole causes little damage other than an unsightly raised bed or a tunnel in the lawn. In a way, they're actually helpful critters as they aerate the soil. Moles produce one litter per year in the spring, and in four to eight weeks young moles reach adult size. They're active year-round but male moles are especially active in February and March when looking for a female, and females are most active in May and June when they are feeding their young.
Since modifying the environment means ridding the soil of beneficial insects and worms, the only effective way to completely eliminate moles is by trapping. Traps are readily available in hardware and big box stores. If you don't mind moles, but don't want them in specific areas of your garden, repellants may work. Castor oil is a common mole repellant, but its efficacy is disputed. Sonic repellants, both solar and battery operated, emit vibrations that may scare away moles. The frequency isn't audible to humans and isn't harmful to children, pets, and other wildlife.
Gophers. Like voles, pocket gophers are rodents and herbivores. They prefer the fleshy underside of plants and roots. Called pocket gophers because of their furry cheek pouches that carry food and nesting materials, these critters are larger than either moles or voles, ranging from six to ten inches long. Gophers have long, yellow-orange front teeth, small eyes and ears, and short tails.
Five gopher species live in California. The most common is Botta's pocket gopher, T. bottae. These pests create an extensive underground burrowing system. Feeding tunnels are usually six to twelve inches below the surface. Nesting and food storage tunnels can be as deep as six feet below the surface. Gopher mounds are crescent-, horseshoe-, or fan-shaped, with a hole that is off to the side and usually plugged. One gopher can create several mounds in a day. Sometimes a gopher can be seen pushing dirt from a mound or feeding at the edge of a mound. They don't hibernate, tunneling through soil all year long, day and night.
Gophers can wreak havoc on a row of plants by pulling entire plants down into their tunnels. They use their sense of smell to locate a source of food, preferring herbaceous plants, shrubs, and trees. Gophers will also gnaw on drip irrigation tubes and hoses.
As with moles, trapping is the most effective way to eradicate the problem of gopher infestation. Make sure children and pets stay away from the traps, because the traps can cause injury. Employing gopher baskets and mesh barriers is an effective alternative. While some roots will escape the barrier, the main roots near the base of a plant will be protected. Sonic repellants my also deter these rodents.
Voles, moles, and gophers can cause havoc in the garden but they can be managed using various methods to control, deter, or eradicate. Consider your natural environment, whether children and pets can be harmed by deterrents, the expense of the deterrent method, and your commitment to the program of eradication when choosing a plan to deal with these pests.
For further information, see:
Baldwin, Roger A, UC IPM's Pest Note on Pocket Gophers.
“Controlling Vole Damage,” University of Nebraska-Lincoln Extension Publications
Pokomy, Kim, “Moles, Voles and Gophers Dig in the Garden,” Oregon State University Cooperative Extension.
Yordan Z, Vole Lifespan and Life Cycle, Insect Cop, May 13, 2020.
UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area, visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu (preferred) or call (530) 538-7201.