Protecting Against Garden Pests

Gardening friends have commented on this season’s unusual uptick in pesky four-legged vertebrates, inspiring this column’s exploration of ways to protect our gardens from these pests.

Our reference to “four-legged vertebrates” narrows the discussion, leaving out the “two-legged” varieties: unauthorized snippers of cuttings, midnight diggers of special plants, clumsy browsers of garden beds, and rambunctious kids.

This exclusion extends to birds (which we might address in the future), bats, and also snakes, which have vertebrae but no legs, and some of which are not pests but assets in the garden.

We also exclude the non-vertebrates, an enormous number of wildlife creatures ranging from small to very, very small. That group is mostly beneficial, although with a good number of bad actors. That category is worth more attention than could fit into a newspaper column.

So, when considering four-legged vertebrate pests, we begin with habitat issues. We can proceed best when we acknowledge that our historically recent gardens are in places where they have lived during many generations. We are intruding into, or reducing, their habitats.

We can’t easily eliminate that interface, so we should try to live harmoniously.

Wild animals prefer to stay away from people, and smart people usually don’t want to interact with wildlife, so both parties are inclined toward peaceful co-existence. Gardeners can support that relationship in two ways without being hostile.

  • Animals are always looking for food, so this means we should not provide food deliberately, or accidentally, e.g., leaving pet food outdoors unattended, leaving kitchen waste in uncovered compost or trash containers, or not harvesting ripe fruit or vegetables. (I think animals are raiding the dropped apples in my garden!)
  • Animals also are always looking for safe spaces to sleep or raise their young. Attractive spaces might be under your house or deck, so close off such spaces with quarter-inch mesh hardware cloth or other materials.

At another level, limit wildlife access to edible plants in your garden. This can be accomplished with fencing that is appropriate for particular pests: high for deer, lower and underground for several smaller raiders, including gophers. Lining the bottom of garden beds with wire mesh or installing gopher baskets can be successful in discouraging gophers. These materials are available in garden centers or on the Internet (see, for example, the website for Gophers Limited.)

A more aggressive approach to limiting access to plants is trapping. Some traps are designed to kill, and others are designed to detain.

Many gardeners are ready and willing to dispatch certain rodent pests, including mice, rats and gophers. Gardeners often regard other rodent pests (squirrels, chipmunks, and porcupines and rodent-related rabbits) as cute and seem them as candidates for release to “somewhere else.” We also would prefer to relocate some other four-legged vertebrate pests, notably raccoons and opossums.

Some people think trapping and relocating a trapped animal pest into nature would be illegal. Our search of federal, state and local government codes revealed a humane requirement to free an animal from a trap within a day’s time, but did not discover a prohibition against relocation. A ban against relocation appears to be an urban myth.

Still, both the Audubon Society and the Humane Society argue that relocation is not a solution to problems with garden pests. Pointing to the territorial habits of wildlife, these groups advise that relocating an animal (a) simply invites another animal to move in its territory, (b) requires the relocated animal to fight the owner the new territory (this could be fatal for a juvenile, or a mother of young animals), or (c) possibly exports disease into the new territory.

These groups basically dislike trapping, and recommend either not attracting wildlife into gardens, or discouraging them with fencing, as suggested above.

Another strategy for dealing with these pests involves using organic fragrances or tastes that animals dislike. We invite interested readers to seek ideas along these lines on the Internet  (search for “animal repellents”).

Then, there are various non-lethal strategies that one might explore, including filling gopher tunnels with water or low levels of carbon dioxide, electrifying fences, making audible or inaudible noises, and other ideas. New ideas pop up often but can be expensive, time-consuming, and of questionable effectiveness.

The final animal control strategy we will mention is the use of poisons. Don’t use them! Poisons can harm pets and children, providing enough reason to avoid them.

Besides, we should treat humanely the animals that share our gardens, even when they eat our plants.

Gopher Overview

Most of these columns are on current priorities in my own garden. The premise of course is that many gardeners could be dealing with the same issues at any given time.

Recently, when we listened to those people who always seem to know what’s going at, we learned that 2012 is a big year for gophers.

In the past, I have relied on two visiting cats to keep my garden gopher-free. (I don’t know where else they get their food, so they probably are feral felines.) The result of their advancing age plus a peak in the local gopher birth rate is a record number of gopher mounds.

It might be possible to avoid gopher problems entirely by limiting the garden to plants that gophers do not enjoy. This approach limits the gardening experience severely and still might not succeed: hungry gophers don’t always follow the rules.

The first step toward “control” (the polite term) is to confirm that you have gophers, rather than relatively harmless moles. Gophers are herbivores; moles are omnivores, but mostly eat earthworms and insects. Gopher mounds are crescent or horseshoe shaped when viewed from above. The hole, off to one side of the mound, usually is plugged. Mole mounds are more circular and volcano-shaped when viewed from the side.

One gopher can create and abandon several mounds in day, so the gardener’s challenge is to find the gopher’s main burrow, which will be six-to-twelve inches deep and connected to a mound. When you see a fresh-looking mound, poke around with a stick or metal probe until you feel a drop of about two inches, indicating that the probe has entered the burrow. This might be the main burrow, where you should set your traps.

Use a shovel to expose the burrow enough to set your traps. The popular Cinch Trap, available at most garden centers, comes in small, medium and large sizes. Use the size that fits snugly in the burrow you found. Set two traps according to instructions (watch your fingers!) and place them in opposite directions in the burrow, to trap the gopher coming from either direction.

Baiting the traps is optional. Fruits, vegetables or peanut butter are good choices. You could also use toxic baits, but that is personal choice and probably not ecologically wise.

Connect the traps to stakes with baling wire or light chain, for easy removal. Cover the excavation with dirt clods, wood, cardboard or anything else to exclude light.

Check the traps regularly and reset them as needed. If you haven’t caught a gopher in three days, try a different location.

Benjamin Franklin probably wasn’t thinking about garden pests when he said, “Energy and persistence conquer all things,” but that’s good advice for gopher hunters.