“Thomomys bottae” may be the scientific name, but if you grow flowers, fruits and/or vegetables, you probably know these destructive pests as “pocket gophers.” These are not the adorable little furry animals from the movie Caddyshack, but are toothy and large-clawed critters that can cause major problems in a garden…and a vineyard is a big garden. Here in California, there are five different species of the rodent, all of them related to the mice family (Geomyidae) but for this article, we’ll chat about the most common bothersome vineyard critter, our Pocket Gopher.
Good question! They are called “pocket gophers” because they carry their excavated dirt in their very elastic “pocket” cheeks that, when full, can extend well back onto their shoulders. They can also turn those dirt-filled cheeks inside out to dispel the gnawed dirt, creating mounds of soil. Gophers have four huge front teeth that continuously regrow as they’re worn down, and can weigh over two pounds, can grow up to 10 inches, with their fur color usually matching the soil in which they live. Pocket gophers in our area are prolific, can begin reproducing at the age of one, have babies up to three times per year, and can live to the ripe old age of three. Aside from the multiple matings throughout the year and the birthing of 2–5 youngsters each time, gophers are solitary critters and live alone, one gopher per burrow system. They are plant eaters (herbivores), and they love to dine on almost anything that’s a plant, above or (annoyingly) below ground level. They move quickly through their elaborate excavated underground tunnels and, unfortunately, love to chomp on (and destroy) the delicate roots of our grapevines. They are most active during the daytime, creating a maze of tunnels 6–18 inches underground, and they safely nest as deep as 6 feet. It’s hard to believe, but one gopher can dig and displace more than two tons of dirt in a year and destroy an area up to 2,000 square feet! To make matters worse, a cranky gopher with sharp teeth and an attitude problem can gnaw through irrigation lines, water lines, and even utility lines.
Diagram by Squire Fridell
The California Department of Fish and Wildlife classifies gophers as non-game animals, so a license is not required for removal and there are many ways to eliminate gophers in the vineyard, some much more effective than others. One “home” method is to mix 3 parts castor oil to 1 part dish soap and then soak the tunnels with that solution. Does it work? Not very well. Some folks may also tout applying garlic repellants, dropping a piece of chewing gum into the burrow, or using an above-ground box that vibrates and emits a high-frequency sound, but again, the results are questionable. That little vibration box might keep a gopher awake all night from the noise and quivering and make him a little cranky (there goes your irrigation lines), but other than that, none of these are very effective.
One foolproof way is pumping and filling the underground tunnels with a mixture of gaseous propane and oxygen. When that combustible gas is ignited with a spark, the entire network of tunnels explodes with dirt flying up in the air out of each gopher hole. It will certainly get rid of your gopher problem, but also pretty much destroys your hillside. It’s pretty cool to see (Google it!) but I definitely wouldn’t try this technique on my own, particularly during fire season….
Some folks have used gasoline or diesel engine exhaust to pump carbon monoxide into the burrow system. This seems like a pretty good plan if you’re a big fan of fossil fuel. One surefire way is to use in-line gopher traps that look a lot like mousetraps. The problem is that the trap is difficult to set (you have to bait it and set it in a tunnel) and tedious to reset because you have to dig the trap up, remove the dead critter, re-bait and re-set. And you have to do all this without getting your fingers trap-snapped. (Ouch!)
For the past 30 years we’ve been using, in tandem, two solutions that are effective. Number one: We have installed a number of barn owl boxes (habitats) around the vineyard ,and these magnificent predators help keep the mice and gopher population under control. Owls only hunt during the nighttime, so you rarely spot them, but they are amazing and majestic animals, sporting a 3-foot wingspan and a heart-shaped white face with brown coloring. They quietly fly and are almost silent when they do so, but they are magnificent if you are lucky enough to see one!
We wish that owls would eliminate all our gophers, but, alas, they don’t. Which gets us to solution number two: We use poisoned gopher bait (0.5% strychnine-laced seed) applied underground with a special insertion tool made by “Gopher Getter.” (Google it. The less-expensive “Midget” model is my favorite.) To make sure that other animals (including owls and pets) don’t eat the bait, it is dispensed underground directly into the gopher tunnels. The Gopher Getter tool consists of a 3-foot, hollow, pointed aluminum tube with a dispenser on top that holds the poisoned seed. When you spot a mound of excavated dirt, there will be a covered-up pop hole right next to it. Then look for a second dirt mound that’s close by, signifying there is an underground tunnel between the two pop holes. You simply poke the tip of the tool into where you think the connecting tunnel might be and the tip will eventually drop into the burrow. Eureka! You’ve found the critter’s highway! Then you simply turn the handle at the dispenser top to drop the poisoned seeds under the ground into the pathway. The next time that little fella comes cruising through his burrow looking for a grapevine root to gnaw on, he happily discovers the bait, eats it and kicks the bucket… underground! I always make sure to kick over the dirt mounds after the application so I’ll know in a day or two if there are any new mounds (which means I didn’t get the rascal). The gopher gets his final meal, but it’s poisoned and the critter dies. And best of all, the gopher expires underground, so other animals won’t find the dead critter, eat it, and get sick. It’s by far the most effective method I’ve found. There are other gopher baits that contain 2% zinc phosphate and anticoagulants, but I’ve found it takes much more of the treated bait to do the job. And, obviously, it is very important to clean up any of the poisoned bait granules that may have fallen above ground.
That’s it! In the last four articles, I’ve covered annoying critters from deer to big birds and from little birds to gophers. May our lives be filled with healthy grapevines and no destructive critters! And remember that if any critter is a wild animal, it’s meant to be wild, so don’t feed it!
My parting quote for this glorious spring day: “Wine and Friends are a Great Blend.” —Ernest Hemingway
