4. Pesticides and their Properties
4.1 What is a pesticide?
The term “pesticide” can be defined simply as any substance which is used to control a pest at any stage in crop production, storage or transport. It is now generally agreed that the term “pest” applies to any organisms that harm crops, be they insects, diseases, weeds, etc.
In the past, there has been some confusion with the term “pesticide” - which has at times been applied specifically to insect control agents - and weed-killers (herbicides) that have been managed separately as an agronomy issue.
The main pesticide groups include:
- Fungicides - for crop diseases such as black pod
- Herbicides - kill weeds
- Insecticides: control insect pests, but they may also be
- acaricides: controlling mites
- nematicides: controlling nematodes (eelworms)
(Note: not all insecticides kill mites and nematodes; on the other hand, many insecticidal products are sold mainly as acaricides and nematicides).
- Rodenticides - kill rats and mice (they are often much less effective against squirrels)
- Other pesticide types include molluscicides (that kill slugs and snails) and bacteriacides, but they are not usually used on cocoa. Occasionally, some substances have multiple action (e.g. metam is a fungicide, herbicide and nematicide).
Each of these main groups are further classified: either according to their chemical type or by their biological mode of action (MoA) - see section 4.5.
Unfortunately, the term “pesticide” is often translated into words that also mean “medicine” or similar. Once again, it is important to be accurate and specific: there is a common misconception amongst farmers that all pesticides do some good, whatever their properties, yet they may actually be harmful.
