Bt (AKA Bacillus thuringiensis) is permitted in organic farming as an insecticide. People have been using Bt’s proteins as a microbial pest control agent (MCPA) in various organic farms for over 50 years. However, is Bt safe for organic gardening?
Bt is safe for organic gardening because it is a natural, non-pathogenic bacterium found naturally in the soil. There are no human health hazards linked with using Bt, according to the EPA (environmental protection agency).In addition, Bt is among the safest natural pesticides used to control caterpillar pests without harming beneficial insects.
In other words, Bt is safe and non-toxic to humans, animals, and beneficial bugs. Even though it is safe for use in organic gardens, wash all vegetables and herbs before consuming them.
After a nearly 2-year long study process, EPA (environmental protection agency) concluded that Bt products would not pose unreasonable dangers to human health or the environment.
Knowing what Bacillus thuringiensis is and how and when it should be used is the key to its success.
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What is Bt or Bacillus Thuringiensis?
Bacillus thuringiensis, often shortened as Bt, is a naturally occurring bacteria that make pests sick when they consume it. For example, when eaten by caterpillars, Bt’s bacteria produce proteins that paralyze the caterpillar’s digestive system causing them to stop feeding and die.
Using Bt helps reduce chemical insecticides in our environment, and it is harmless when consumed by beneficial insects and animals. Several studies revealed that applying Bt in your garden is perfectly safe in its ingestion and application by humans.
The alkaline pH gut of caterpillars, which is greater than 7.0, activates Bt. However, acid-gutted or stomached creatures cannot be affected; therefore, humans and mammals are not in any way affected by Bt, according to studies.
Managing pests with Bt depends on its active ingredient, a crystal protein paralyzing the insect’s digestive system. The infected insect stops feeding and starves to death.
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Why Use Bt (AKA Bacillus Thuringiensis)?
Bacillus thuringiensis (Bt) products are increasingly used in agriculture to replace chemical insecticides in pest control. In addition, most chemical insecticides kill pest insects quickly and are toxic to beneficial insects, including lady beetles and parasitic wasps, and other species in the garden.
- B.t products are non-polluting, and you can use them where other pesticides may cause contamination to the surface and groundwater.
- B.t. is cost-effective when compared with other pesticides.
- Pest control with Bt has become a miraculous tool for eliminating specific insect species from commercial and home gardens.
While the original strains of Bt pest control were directed at caterpillars, including tomato hornworms, corn borers or earworms, cabbage loopers, and leaf rollers, new strains have been developed to attack particular types of flies and mosquitoes.
How Should You Apply Bt Products?
- Carefully read the label and follow the indications because Bacillus Thuringiensis products are insects specific.
- Make sure that the insect is in its larval stage when applying any Bt products because you will have better control if the larvae are still tiny. And remember that, for Bt to work properly, the caterpillar has to eat it.
- Apply Bt products carefully, and make sure you limit your spraying to the affected plants so that you only target the caterpillars that are causing issues.
- Properly store Bt, since products only last a few years, with the powdered forms lasting longer than liquids. Try to store Bt in a cool, dry, shaded place for maximum shelf life.
- Be patient when applying Bt products and give Bt enough time to work, as it will take several days to notice its effects. In most cases, people applying only chemical pesticides are used to the immediate effects on insects’ nervous systems and, therefore, might think Bt pest control doesn’t work when they see the insects still moving.
- Use Bt only when needed to prevent developing Bt immunity; apply Bt only if necessary. And use Bt as part of your integrated pest control program that preserves beneficial bugs.
- Even though Bt products pose no harm to adult butterflies, it targets and kills young butterflies (larvae, caterpillars)
- Generally, the best time to use Bt products in your garden is early evening or morning.
- To be safe, wear gloves, long sleeves, and pants when applying Bt. And then wash thoroughly after.
- Insects attacking a plant’s roots or insides will not be affected since you apply Bt products on plants’ foliage.
- The National Pesticide Information Center provides a list of tips to reduce risk when using pesticides around pets.
- Bt is generally effective only when consumed by the insect as a larva and ineffective against most adult insects.
- The EPA exempted Bt from groundwater restrictions and concluded that Bt products have no known effect on wildlife, including birds, mammals, and fish.
- Typical agricultural formulations include:
- Wettable powders
- Spray concentrates
- Dust
- Liquid concentrates
- Baits
- And time-release rings.
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Common Types of Bt Products and The Type Of Pests They Control
There are several types of Bt, and each is specific to different insects. Since Bt is species-specific, beneficial, and non-target, insects are usually not harmed.
Also, insects that attack a plant’s roots or insides will not be affected since you apply topically and because Bt is not a broad-spectrum insecticide.
Make sure you carefully read the product labels before treatment to ensure your target pest is included. Here’s a snapshot of general recommendations for each Bt and its targeted insects.
| Bt Strain | Insects Killed by Bacillus thuringiensis |
| Bt kurstaki (Btk) | This is the most common strain of Bt. It kills leaf and nettle-eating caterpillars, including: – Bagworms – Gypsy moth larvae – Cabbage worms – Tent caterpillars – Leafrollers – Tobacco hornworms – Tomatoes – Tobacco hornworms – And European corn borers. |
| Bt san Diego (Bt-sd) | This particular type of strain of Bt targets: – The elm leaf beetle – Cottonwood leaf beetle – And potato beetle. |
| Bt israelensis (Bti) | This type of Bt targets: – Mosquitoes – Gnats – Black flies – Blackflies – Midges |
| Bt aizawai (Bta) | Wax moth larvae in honeycombs |
| Bacillus popilliae | Bacillus popilliae helps kill Japanese beetles with milky spore disease. |
When Should You Apply Bt?
Bacillus thuringiensis products are susceptible to degradation by sunlight; therefore, the best time to use in your garden is early morning or evening.
Generally, Bt adheres to plant foliage for less than a week after application, but certain weather conditions, such as rain or overhead watering, shorten its efficacity period.
Buy the suitable Bt products for your problem and use them as directed.
Tips For Improving Bt Products Effectiveness:
- Choose the right product of B.t. for the insect you want to control
- Do not apply the first spray of Bt products until all caterpillars in the area have hatched.
- Since high pH can reduce B.t product effectiveness, avoid high pH water when mixing B.t. sprays
- Use B.t. products spray within 12 hours of mixing.
- Apply Bt when winds are relatively calm to prevent spray drift.
- Ensure the time you apply B.t products coincide with the most vulnerable life stage of pests.
- To improve the effectiveness of the spray, add a spreader to the tank mix.
- Reapply the spray in the event of heavy rainfall within 8 hours of application.
- And always carefully read the product information before purchase and use.
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How Long Does It Take For BT To Work?
Depending on conditions, the bacteria may remain effective for as long as 22 days or may become ineffective after 24 hours. Under natural conditions, Bt products are active for three to seven days after spraying.
Bt pest control products have a shorter shelf life than most chemical insecticides, and you should store Bt products in a cool and dark place.
Wrapping Up
Overall, Bt is a safe and natural bacteria commonly found in soil and an excellent way to maintain the natural equilibrium of your garden’s ecosystem.
When you choose to protect your garden with Bacillus thuringiensis (Bt), you can rest assured knowing your kids, pets, and crops are safe. And, above all, you are contributing to keeping your planet healthy and safe.
