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In the last few decades, there has been a call to move away from traditional, highly toxic agricultural inputs to safer, less toxic products. As such, there has been a greater emphasis on research into and development of biological products. This has led to a flood of new products available to producers that are often confusing to the user.

Hortgro has asked industry expert, Sheila Storey from Nemlab, to help create a basic understanding of bioproducts to help producers make informed decisions and manage risks.

In this series, Sheila will explain:

  • how bioproducts can improve production;
  • what to look for to make sure that the product is authentic;
  • the products currently available in SA;
  • and some guidelines on how to test these products on farm.

According to Sheila, bioproducts can be divided into two broad categories: biostimulants and biopesticides. In this communique, the similarities and differences between these categories, within each area, will be highlighted. It is important to remember that some products can be both a biostimulant and a biopesticide. Remember that this should be explicitly stated, says Sheila.

What are biostimulants and biopesticides?

It is very difficult to find a single definition but some of the definitions include:

A  biostimulant  (according to Act 36 of 1947) is a fertilizer that contains a natural or synthetic substance/substances or organism/organisms which maintains the growth or yield of plants or the physical, chemical or biological condition of the soil.

It can also be described as a “soil improver” (

The South African Bioproducts Organisation (SABO) defines biostimulants as products that stimulate natural processes in or on the plant or around the roots to enhance nutrient uptake, nutrient efficiency, increased tolerance to abiotic stress, and crop quality, vigour and yield.

Jardin (2015) in a scientific paper on biostimulants defines a biostimulant as any substance or microorganism applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits, regardless of its nutrients content.

Definitions for biopesticides (bionematicides/ natural pesticides) include a mass-produced agent manufactured from a living microorganism or a natural product and sold for the control of plant pests (Organisation for economic co-operation and development of 2009).

The US EPA defines biopesticides as certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. SABO refers to biopesticides as biocontrol agents/products. Biocontrol is defined as the use of living organisms, such as insects, or bacterial and fungal pathogens, to control pest populations.

A scientific definition of biopesticides (Oguh et al., 2019) defines natural pesticides or biopesticides as pesticides made by organisms usually for their own defence, or are derived from a natural source such as plant, animal, bacteria, and certain mineral, use to control pest naturally with less effect or no effect.

Despite the many definitions, the common thread through all the definitions are described below:

Biostimulants Biopesticides
It is a substance or microorganism.


It is either a naturally occurring organism or is produced by a naturally occurring organism


Its effect is directed at the plant. Makes the plant grow better.


Its effect is directed at a particular pest. It reduces pest numbers.
It improves yield through the direct effect on the plant or soil.


It improves plant yield through pest control



“The main difference between a biostimulant and a bionematicide is the target organism. A biostimulant is aimed at improving plant growth while a biopesticide is aimed at reducing pest numbers.”


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