Trap the Woodchuck to Kill It
You can try setting traps. Remember, trapping an animal live is not intended to allow you to move the critter to someone else’s territory. If you trap a pest animal you must find a way to humanely kill it.
Commercial woodchuck traps are available. Box traps that measure 12 by 12 by 36 or 42 inches are recommended. Garden supply catalogs, hardware stores, garden centers are a source for these traps. Buy only an expensive trap. “HavAHart” often recommended. These critters are strong of body with strong legs and sharp teeth which can chew/or break through cheaply made metal traps. Place logs from the hole to the trap to funnel this garden-eater into the trap entrance. Bait with apples, carrots and fresh greens. If you use these items, make certain they are kept fresh by renewing the bait every couple of days.
Set your trap at dawn, and disarm it overnight to avoid catching a skunk. Woodchucks are most active early in the morning and at dusk, but will also venture out during the day.
If you have not caught the beast within a week, sell the trap and take the money and buy a fence.
Another option is to plant a trap crop. Raise a patch of alfalfa and clover at least 50 feet away from the food garden. This may attract the woodchuck away from the vegetables.
Kill the Woodchuck With Fumigation
Fumigating the woodchuck's tunnel system can be one way to solve the problem. For directions on how to do this see Best Control Strategy under Gophers.
Ammonia for Woodchucks? - A Minnesota gardener suggests a small ammonia-soaked sponge placed into a woodchuck hole (with that hole and all of the other holes connecting to the same burrow, plugged up) will quickly cause an abandonment of the burrow. Plugging all the holes does not prevent the woodchuck from escaping. The woodchuck can dig through loose dirt in a lickity split. Plugging the holes permits the greatest concentration of fumes to reside in the tunnels and not escape to the surface. Best time to do this is in early spring.
Avoid Using Poisons
Some farm-supply stores sell a poison gas cartridge for woodchuck control. We are not taking a position on this method because of the potential danger and local ordinances. When ignited, they produce carbon monoxide and sulfur dioxide. Check your state’s requirements before buying.