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  • Writer's picturePhilip


I cannot say I was a great fan for the music of Lulu but the lyrics of her songs occasionally ring in my ears; most recently this song lyric, all around the subject of Biocontrol, Biopesticides and Bio-stimulants.

There are a lot of different “biological” products on the market. Frankly, the terms used to describe them can be a little confusing. So, let’s consider a little of what they mean.

What is a pesticide?

A pesticide is a substance or mixture of substances used to kill pests or to prevent or reduce the damage pests cause. The term “Pesticide” therefore refers to the likes of herbicides and fungicides although it is often incorrectly used to refer solely to Insecticides.

Pesticides are defined by their purpose, not by their ingredients, hence they may be chemicals, plant extracts, or microorganisms, but their purpose is to prevent damage.

“Biopesticide” is a term defined as “certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals.” All biopesticides are pesticides, and must be handled and applied as such.

Biopesticides fall into one of three groups:

  • Microbial

The active ingredient is a living microorganism (fungi, bacteria, viruses, protozoa) or a product made by a microorganism

  • Biochemical

Natural compounds including both plant extracts and naturally-occurring chemicals

  • Plant-incorporated protectants

The products that result from inserting new genes into plants (i.e., the result of genetic engineering.) I didn’t know this one!

As an example of “fungicidal action” Biopesticides control plant diseases in five ways:

Consuming or parasitizing the pest.

A beneficial fungus that eats a pest fungus, or a beneficial fungus that infects and kills a pest insect.

Poisoning the pest

Some microorganisms produce antibiotics that are toxic to pests. There are numerous bacteria that do this.

Crowd out the pest.

Pest microorganisms (pathogens) can’t colonize and invade a plant if the surface of the plant (leaves, roots, etc.) are already covered with beneficial microorganisms.

Stimulating plant defences

Although very different from human immune systems, plants do practice self-defence. Beneficial microorganisms can cause plants to “turn on” their defences before they encounter a pest. The plant is then less likely to be damaged by the pest.

Promoting plant growth and stress tolerance

Healthier plants are more resilient when faced with a disease. If the purpose of the product is to protect the plant from disease, this would be its mode of action.

Sometimes a single biopesticide functions in more than one of the above ways. But, again, the purpose of using a biopesticide is to control a pest.

Pest: Noun

An insect or small animal that is harmful or damages crops.

An annoying person, especially a child. Someone or something that annoys you

Examples of pest.

Insects are more likely to become pests.

Organic farmers would explain that crop diversification and timing of planting helps them withstand threats from agriculture induced pests and diseases.


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