Why do we need pesticides?  Pesticides refers to insecticides, fungicides and herbicides.  To protect our plants from insect and/or fungus damage or the competition from weeds for water, plant food and space in the beds. Where do pesticides come from? The big multinational companies do the basic research and development of a product at very high costs.  For that they get a 20 year patent protection to recoup the costs involved in the development phase. The development phase takes about 15 years which consists of the chemical, biology efficacy and toxicology studies and out of a 100 new chemistry only 3 will reach the final stage – total cost per product $160 million.

All agricultural, home, garden pesticides and fertilizers offered for sale in the Republic must be registered with the Department of Agriculture in terms of Act 36 of 1947.  To obtain a product registration in terms of the Act, all usage and efficacy claims are scrutinized and only on verification of all application details and claims, will a registration be granted by the Department. For pesticides an L number is allocated and for fertilizers a K number and this number must appear on all approved labels of that specific product.

The label of a product is a legal document and the wording was approved by Act 36 of 1947 and may not be changed without approval of the Registrar.


Virtually all pesticides used as insecticides, fungicides and herbicides are formulated into the most suitable formulation to enhance the efficiency of the specific product and to make them most suitable for application taking the pest and surface into consideration. Note: Pest can be either an insect, fungus or weed. Some of the most common formulations available are as follows:

Aerosol dispenser AE Active enclosed in a container, dispersed by depression of a valve.
Dustable powder DP Free flowing powder for dusting.
Emulsifiable concentrates EC A homogenous liquid, diluted in water before application.
Granular Bait GB Small hard round granules containing pesticide for scatter applications as bait, or in soil, or on the plant (funnel stage).
Granule GR Free-flowing solid product of defined granule size range, ready for use.
Bait (ready for use) RB Designed to attract and be eaten by target pests.
Suspension Concentrate SC Suspension of active ingredients in a fluid for dilution in water before use.
Water Soluble Powder SP Powder formulation to be applied as true solution of active ingredient after solution in water.
Vapour releasing product VP Containing one or more volatile ingredients. Controlled evaporation rate using suitable formulation/dispensers.
Water Dispersible Granules WG Applied after disintegration and dispersion in water.
Wettable Powder WP Powder formulation dispersed in water and applied as a suspension.


Pesticides can be grouped into three general classes according to the mode of action, namely :-

Stomach pesticides, Contact pesticides and Systemic pesticides.  Some pesticides can be grouped in two or more groups like stomach/contact or contact/systemic etc.

On application of a pesticide to a surface for example  plant, tiles, wood etc, as a thin layer, it remains to continue its action (called residual action), which can vary from hours to weeks depending on its specific properties and natural factors, i.e. weather, temperature, light and surface type.

Contact pesticides kills on contact of the pest – insect, fungus, weed - and are effective for example against biting insects like beetles.

Stomach pesticides are effective against eating insects for example worms.

Systemic pesticides are effective against sucking insects like aphids.

A number of pesticides, fungicides and herbicides are systemic in action and will penetrate into the leaf or root tissue of the plant and dissolve in the sap stream and be transported to other parts of the plant to kill certain sap sucking insects or fungi present.  These compounds mainly move upwards in the plant and will be most effective if the plant is growing vigorously. Some pesticides are only local-systemic where it is only absorbed into the first two layers of cells on plants.


All insecticides, fungicides and herbicides must be considered as toxic in terms of storage, handling and application. Herbicides are usually less toxic than insecticides and fungicides. Less toxic formulations to humans, animals and plants (environment) are replacing or superseding older compounds, without compromising efficacy.

Toxicity is conveniently expressed as an LD50 value, i.e. (Lethal) dosage of chemical as mg per kg body weight, that will kill 50% of a random sample, of a population of test animals  – e.g. high LD50  – safer formulation like 2000mg/kg; lower figure more toxic like 3mg/kg.

If your bodyweight is a 100kg 2000 mg x 100kg = 200kg will be detrimental to you and 3mg x 100kg = 0.3kg of a more toxic product will be the same.

LD50 oral and dermal can be used to determine levels of toxicity for comparative purposes. Note that the LD50 of the pure active ingredient will be more toxic than a formulation containing the same active because a formulation contains less active ingredient. The active ingredient on its own is usually a 90% plus pure but formulations contains anything from 0.0005g a.i /ℓ or kg to 800g a.i /ℓ or kg of the active ingredient.

For home and garden use the more safer products are used because the gardeners using the products are not so well informed as farmers in using the product and the application is also not always so accurate. Apart from some rodenticides that might have a red band no other red band product will be allowed to be used in the home and garden. The tendency is to only have blue and green banded products on the shelves available to homeowners. 

There is a whole list of pictograms available to illustrate to users how to use the product especially for those that cannot read. On agricultural pesticides it is compulsory to use all the pictograms but for the home and garden products only two have to be used:

Store behind lock and key

Lock and Key
Wash your hands

Wash your hands


Pesticides are categorized in four main groups, i.e. I – IV, according to the concentration of the active ingredient used in the formulation.

The new system of identification are colour bands used according to the hazard of the formulation and are linked to the WHO Hazard Classification Scheme with specific colours in the Coats and Pantone range of colours:

Very Toxic






This colour coding system conforms to international norms and practices and includes a UN number for the purpose of packaging standards.

Poisoning must be avoided in all cases when a pesticide is been used. Make sure the containers are solid, leak proof, with appropriate caps and seals and a legal label with all necessary instructions how to use the product, the necessary warnings and precautions to prevent poisoning of people, domestic animals and the environment, damage to plants and crops. Also note the special advisory and emergency numbers on the labels. Seek professional help and advice whenever a poisoning case may occur.

Whenever handling or spraying a pesticide wear protective clothing like:

  • Rubber gloves.
  • Thin cotton overall or long sleeved shirts and long pants.
  • Thin cotton hat.
  • Breather mask.


Pesticides should be carefully packed in a cool, well-ventilated area, separate from food and feeds.  Store herbicides away from insecticides, fungicides and fertilizers.

Transportation must be done in a suitable, ventilated vehicle to avoid breakage and spillage. All the necessary documentation like tremcards, MSDS’s etc should be available on the truck as well as all the necessary decals on the outside of the truck.

Storage area must have bunding to contain any major spills. Store away from any other commodities and combustible products.  Emergency equipment like firefighting and first aid equipment should be available. Have emergency service numbers and poison centre numbers clearly displayed.


A pesticide can only perform as good as it was applied. The correct and proper selection and application of garden chemicals is crucial in terms of efficacy or results achieved. A good product applied wrongly will give poor efficacy and a inferior product applied correctly can give excellent results! A quality garden sprayer to apply the product with is therefore a necessity.  Recommendations for dosage or concentration (A.I. to water) are clearly indicated on the approved label and should not be exceeded – if so damage to plants etc can occur. Never use a product for any other purpose not indicated or registered for on the label.

Also note that the recommended dosage indicated for insecticides and fungicides will be for example 10mℓ /10ℓ water but for herbicides it will be 10mℓ /10ℓ water/ 100 sq. meters.  This indicates that the 10ℓ of spray mixture must be applied onto the 100sq meters but in the case of insecticides/fungicides it is a volume spray applied onto a surface, like a plant, to just before drip-off.

When a pesticide will be used the following steps must be followed:

  • Identify the problem – insect, fungus, and weeds.
  • Choose the right product to use.
  • Read the label and follow the instructions.
  • Apply the product according to the label with a suitable sprayer.

 The reason for unsatisfactory results can be:

  • Wrong product.
  • Poor application.
  • Weather conditions.
  • Surface applied to.
  • Etc.


Cover (application) – A light even application to the whole plant, but not necessarily covering all surfaces.  Suitable for systemic pesticides.

Full cover (application) – A thorough application covering all plant surfaces, usually applicable to contact and stomach poisons.  Extremely important in the case of insecticides/fungicides.

Spot treatment – A specific application at a particular site or area, mainly herbicides.

Spray applications should be done in early morning or late afternoon in wind free, dry conditions.  Droplet size is important from a coverage and spray drift point of view, a well-directed spray is advisable.  If only one plant is infested do not spray the whole garden but only the infested plant. By doing this the impact on the environment will be very small and you do not waste product. Repeated sprays might be necessary to get proper control. In the case of fungicides this is very important because you have to spray preventatively in a spray program.  With insecticides it is usually a corrective spray when the insects are visible.  Herbicides can be applied pre-emergence or post-emergence of the weeds and the control can either be selective, only some weeds will be controlled by applying for example Kombat Weeds and others will still grow, or non-selective where all weeds spayed will be controlled by applying for example Kombat Wipe Out.