Chemical Deer Repellent: Facts and How They Work

When deciding on a deer repellent strategy, you should read some tips on product selection and use. Repellents are an important part of a multi-faceted approach to controlling deer. Just as some plants are eaten in some areas and not in others, different animal repellents work differently. You can see variations in the way deer react depending on species, regions, seasons, and plants. If there is a lot of plant material for deer to choose from it is easier to repel them. If there isn't much choice of other plants or there is such a high population of deer to plants, the deer are more desperate and hard to control.

Deer repellents generally rely on fear, conditioned avoidance, pain, or taste. Fear-inducing repellents contain compounds that emit sulfurous odors (such as predator urine, meat proteins, or garlic). We interpret the avoidance of these odors as a fear response, suggesting herbivores perceive sulfurous odors as indicators of predator activity. Deer have conditioned avoidance occurs when ingestion of a food is paired with nausea or gastrointestinal distress.

Animals generally don’t eat as much of a food if it is associated with illness. Active ingredients, such as capsaicin, allyl isothiocyanate, and ammonia, cause pain or irritation when they contact trigeminal receptors in the mucous membranes of the mouth, eyes, nose, and gut. An inherent problem of using pain repellents is that they are universally aversive to all mammals. As we know, bad taste can also induce avoidance. Bittering agents are often used to induce a bad taste. Unfortunately, while omnivores normally avoid bitter tastes, herbivores are generally indifferent, at least at the concentrations used in most repellents.

Modes of Action

Deer repellent falls into two modes of action. There are also repellents that combine both modes. Contact, also called taste repellents, are applied directly to plants, causing them to taste bad. Examples include Bobbex, Hot Pepper Wax, and Treeguard. The other type of repellents are Area, also called odor repellents. These are placed in a area you want to keep deer out of and the deer are repelled by the foul odor, or frightened by the odor of humans or other predators. Examples are Plantskydd, Deer Away, and Deer Scram.

There are also several products for a deer proof garden that combine ingredients or have ingredients that work as both taste and odor repellents. Examples of combination products are Deer-Off, NIMBY, and Deer Ban.

Control products come in ready-to-use liquids, granules, bags, and powder that can be mixed with water. If you prefer, you can make your own products for a deer-proof garden. Repellents can eggs, peppers, dish soap, fertilizers, bars of soap such as Dial and Lifebuoy, garlic cloves, human hair, urine from coyotes, and even large cat feces from local zoos. Check out our whole page of homemade deer repellents recipes that you can make yourself.

Common Ingredients

Chemical repellents can be an effective method for controlling deer populations, but it's important to use them correctly and in compliance with local regulations. Here are a few examples of chemical repellent ingrediants that are commonly used for deer control:

Thiram: This fungicide can also act as a repellent for deer, it is often used as a spray or granular form to protect plants and crops.

Hot pepper spray: Capsaicin, the chemical that makes hot peppers spicy, can also be used to make plants unappealing to deer. This can be made by mixing hot pepper flakes or powder with water and then spray the mixture on plants.

Garlic: Garlic can be made into a repellent by blending it with water and then sprayed on plants.

Egg Based Repellents: Eggs can be used to make a repellent spray, which can be made by mixing eggs with water, and then spraying the mixture on plants.

Ammonia: Ammonia-soaked rags or a spray solution can also be used as a repellent, it produces a strong odor that deer find unappealing.

It's important to note that the effectiveness of these repellents can vary depending on the specific location and situation, and it's always a good idea to test a small area before applying repellents to large areas or important crops. Additionally, it's important to comply with local regulations, read the label carefully, and follow the instructions for application, storage, and disposal of any chemical repellents. Furthermore, keep in mind that chemicals can be toxic, and some can be harmful to people, animals, and the environment, so always use them with caution.

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