Pocket gophers
Thomomys and Geomys spp.
A western burrower that eats roots from below and pulls whole plants down into its tunnel. Wire baskets under the root ball are the only thing that really works.
How to know it
Rarely seen. Read the mound: a gopher throws up a fan- or crescent-shaped heap of soil with a plugged hole off to one side, quite unlike the mole neat cone with the hole in the middle. The animal itself is a stocky rodent 15–25 cm with large yellow front teeth outside its lips and fur-lined external cheek pouches.
What you'll see
- Crescent or fan-shaped soil mounds with a plugged entrance at one edge.
- Whole plants disappearing downward, or wilting suddenly with the roots gone.
- Young trees and shrubs girdled below ground and dying or falling over.
- Irrigation lines and drip tubing chewed through.
- Bulbs, potatoes and carrots removed cleanly from below with no surface disturbance.
Where it comes from
Solitary and territorial except when breeding, active all year and mostly underground. One animal maintains an extensive tunnel system and will not tolerate another in it, so a garden usually has one gopher per patch of damage. One to three litters a year; the young disperse across the surface in spring and early summer, which is when new gardens are colonized.
The western half of North America, in light, well-worked, irrigated soil — which describes a vegetable garden precisely. Damage peaks in spring and autumn and continues through winter.
Dealing with it
- Line raised beds with hardware cloth underneath, and plant valued shrubs and trees in wire baskets. Exclusion is the only reliable answer.
- Trap in an active main tunnel, found by probing beside a fresh mound; set two traps facing opposite directions and check daily.
- Flooding, smoke bombs and sonic spikes do not work; skip them.
- Fence a vegetable garden with mesh sunk 60 cm and turned outward at the bottom.
- Protect young fruit trees with a wire basket at planting, which cannot be done retrospectively.
Keeping it out
- Install the wire under new raised beds and around new trees at planting time.
- Keep the garden boundary mown and clear so dispersing young are exposed and slow to settle.
- Deal with a new mound immediately; one gopher is far easier than an established system.
- Encourage owls with a nest box and leave the gopher snakes alone; both take a real number.
- Avoid deep loose mulch over the whole area, which makes tunnelling easier.
What it goes for
Carrots, potatoes, lettuce, strawberries, bulbs, hostas and the roots and bark of young trees and shrubs.
See also
The Cottage Garden Companion — the gardener's bestiary at cottagegardencompanion.com