The appearance of damaged tomato fruit often signals the presence of chipmunks. These small rodents are foraging pests that damage plants while seeking sustenance or moisture. Understanding their motivations allows for the implementation of humane, practical measures to protect your harvest. A successful strategy involves physically blocking access and making the tomato patch undesirable.
Why Chipmunks Target Tomato Plants
Chipmunks target tomato plants for two main reasons: nutrition and hydration. During dry periods, the juicy pulp of a ripening tomato provides a readily available source of water. This search for moisture often results in the characteristic single bite taken out of multiple fruits, which are then left to rot.
The sweet pulp of ripe tomatoes is also a high-energy food source, making them a target for consumption and caching. Chipmunks are habitual burrowers and diggers, which means they can disturb the root systems of young tomato plants while creating burrows or burying stored seeds. This constant activity near the base of the plant can cause secondary damage.
Exclusion Methods: Physical Barriers
The most reliable approach is to physically exclude chipmunks from accessing the plants. This requires creating a complete enclosure around the tomato patch or individual plants using a fine, sturdy mesh material. Hardware cloth, a woven or welded wire mesh, is considered the most effective option because of its durability.
A quarter-inch (1/4-inch) opening is recommended, as chipmunks can easily squeeze through larger openings like standard chicken wire. Any protective barrier must extend around the entire plant and prevent digging from below. To achieve this, the base of the mesh enclosure should be buried six to twelve inches deep into the soil.
An alternative method is to bend the bottom six inches of the hardware cloth outward in an “L” shape before burying it just below the surface. This horizontal barrier prevents the chipmunk from simply digging straight down at the fence line. For tall tomato plants, the enclosure must also be covered on top to prevent the agile rodents from climbing over the side and dropping in.
Repulsion Methods: Scent and Taste Deterrents
Repellents work by making the tomatoes unappealing to the chipmunks through strong scent or taste. Capsaicin, the compound that gives chili peppers their heat, is a widely used taste deterrent that irritates the sensitive nasal passages of mammals. Homemade sprays can be created using cayenne pepper or commercial capsaicin concentrates, aiming for a concentration between 0.1% and 0.5%.
A typical homemade mixture combines one tablespoon of cayenne pepper powder with one quart of water and a small amount of dish soap to help the solution adhere to the foliage. These taste-based sprays should be applied to the surrounding soil and the lower, non-fruiting parts of the plant, but not directly onto the edible tomatoes. The effectiveness of any capsaicin-based repellent is temporary, and the spray must be reapplied frequently, especially after rainfall, to maintain its potency.
Another effective category utilizes scents that mimic the presence of predators. Commercial granular or liquid fox urine products can be used to create a chemical barrier around the garden area. Chipmunks instinctively avoid areas where they detect the scent of a primary predator, creating a sense of danger in the treated zone.
The predator urine can be sprayed along the perimeter or placed in small, vented containers or cotton balls near known entry points or burrows. Other strong-smelling, non-toxic substances like peppermint oil or garlic oil sprays can deter chipmunks, as they rely heavily on their sense of smell for foraging. Consistent reapplication is necessary, as the volatile compounds quickly dissipate in the outdoor environment.
Long-Term Prevention Through Habitat Management
Long-term management focuses on making the yard environment less attractive to chipmunks, reducing the local population pressure on the tomato plants. Chipmunks seek shelter and nesting sites in dense cover, so removing potential harborage areas is a practical first step. This includes eliminating brush piles, reducing excessive ground cover, and stacking firewood away from the house or garden structures.
Spilled bird seed is a major attractant, as it is a high-calorie food source that sustains large populations. Moving bird feeders at least 15 to 30 feet away from the garden and using feeders equipped with seed-catching trays will reduce the amount of accessible food on the ground. Switching from chipmunk favorites, like sunflower seeds, to alternatives may also help.
Chipmunks burrow under foundations, patios, and sheds, and sealing these entry points can limit their presence near the garden. Inspecting the home and surrounding structures for small cracks or openings and sealing them with masonry repair or 1/4-inch hardware cloth will deny chipmunks access to secure nesting spots. Keeping the garden area free of debris and fallen fruit will minimize easy food sources.