Is Bt Safe for Organic Gardening?

Bt (Bacillus thuringiensis) is recognized in organic farming as an insecticide, and for more than 50 years, Bt proteins have been used as microbial control agents (MCPA) on a variety of organic farms. So, is Bt suitable for organic farming?

According to the EPA (U.S. Environmental Protection Agency), there is no human health risk associated with the use of Bt. Bt is also one of the safest natural pesticides used to control caterpillars without harming beneficial insects.

In other words, Bt is safe and harmless to humans, animals, and beneficial insects. Even though it is safe to use in organic gardens, all vegetables and herbs should be washed before eating.

 The EPA (Environmental Protection Agency), after a nearly two-year research process, has concluded that Bt products do not pose an unreasonable risk to human health or the environment.

 What is Bacillus thuringiensis?

Bacillus thuringiensis, often abbreviated as Bt, is a naturally occurring bacterium that causes disease when pests eat it. For example, when a caterpillar eats Bt, the bacteria in Bt produce a protein that paralyzes the caterpillar’s digestive system, causing the caterpillar to stop eating and die.

The use of Bt helps reduce the number of chemical pesticides in the environment and is harmless for beneficial insects and animals to eat. According to some studies, spraying Bt in the garden is perfectly safe for humans to ingest or spray.

The intestines of caterpillars have an alkaline pH of over 7.0, which activates Bt. However, creatures with acidic intestines and stomachs are unaffected. Therefore, studies have shown that humans and mammals are not affected in any way by Bt.

Pest control with Bt is based on the fact that its active ingredient, a crystalline protein, paralyzes the digestive system of insects.

Why we use Bt ?

Bacillus Thuringiensis (Bt) products are increasingly used in the agricultural sector as an alternative pest control agent to chemical insecticides. Most chemical insecticides kill pests quickly and are also toxic to beneficial insects such as ladybugs and parasitic wasps, as well as other species in the garden.

– Since B.t products are non-polluting, they can be used in areas where other insecticides may contaminate the ground surface or groundwater.

– B.t. has excellent cost performance compared to other pesticides.

– Pest control with Bt has become a miraculous tool for eliminating certain insect species from commercial establishments and home gardens.

The original pest control with Bt was caterpillars such as tomato hornworm, corn borer or earworm, cabbage looper, leaf roller, etc. New strains have also been developed that attack specific types of flies and mosquitoes.

How do I use Bt products?

·     Bt products are insect-specific, so read the label carefully and follow the directions.

·      When applying Bt products, make sure the insect is in the larval stage. The smaller the larvae are still, the better control you will have. Also, remember that for Bt to work properly, the caterpillars must eat the Bt.

·     By applying Bt products carefully and limiting the application to affected plants, you can target only the caterpillars that are causing the problem.

·      Bt products will only last a few years, but the powder will last longer than the liquid, so store it properly Bt should be stored in a cool, dry, shady area.

·     Be patient and allow plenty of time for the application of Bt products, as it will take several days to see the effects. Most of the time, people who use only chemical pesticides are used to the immediate effect on the insect’s nervous system, so when they see the insects still moving, they may think that Bt pest control does not work.

·     To avoid becoming immune to Bt, use Bt only when necessary and use Bt only when necessary. Bt should also be used as part of an integrated pest control program to maintain beneficial insects.

·     In general, the best time to use Bt products in the garden is in the evening and morning.

·      For safety reasons, wear gloves, long sleeves and pants when using Bt formulations. And wash well after use.

·     Because Bt products are applied to plant foliage, insects that attack the roots and interior of the plant are not affected.

·     The National Pesticide Information Center has compiled a list of tips to help reduce the risks of using pesticides around pets.

·     Bt is generally only effective when eaten by insects as larvae, and has no effect on most adult insects.

·     EPA has exempted Bt from groundwater regulations

Types of Bt products and types of pests to be controlled

There are several types of Bt, each specific to a different insect; because Bt is species-specific, beneficial, and non-target, insects are usually not harmed. Also, insects that attack the roots or interior of the plant are not affected because Bt is not a broad-spectrum insecticide, as it is applied topically.

Before treating, read the product label carefully to make sure it contains the target pests. Here are some general recommendations regarding each Bt and its target insects.

When to use Bt agents?

Bacillus thuringiensis products are susceptible to degradation by sunlight, so early morning or early evening are best for use in the garden.

Typically, Bt will adhere to plant foliage within a week of application, but weather conditions such as rain or overhead spraying may shorten the duration of effectiveness.

Tips for increasing the effectiveness of Bt products

·      Choose the right B.t. product for the insect you want to control.

·      Do not make the first application of B.t. products until all caterpillars in the area have hatched.

·      Avoid water with a high pH when mixing B.t. sprays, as high pH reduces the effectiveness of B.t. products.

·      B.t. products should be sprayed within 12 hours of mixing.

·      Spray B.t. products when the wind is relatively calm to prevent drift of the spray solution.

·      Time the spraying of B.t. products to coincide with the most vulnerable life stage of the pest.

·      To increase the effectiveness of the spray, add the spray product to the tank mix.

      If heavy rain falls within 8 hours of spraying, re-spray.

    Also, be sure to read the product information carefully before purchase and use.

How long does it take for BT to be effective?

Depending on the conditions, the effect may last as long as 22 days, or it may lose its effect after 24 hours. Under natural conditions, Bt products are effective for 3 to 7 days after application.


Bt is a safe, natural bacterium found in soil and is an excellent way to maintain the natural balance of your garden ecosystem.

If you protect your garden with Bacillus thuringiensis (Bt), you can rest assured that your children, pets, and crops will be safe. And most importantly, you are helping to maintain the health and safety of our planet.

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