A pesticide is a substance used to destroy, prevent, control, attract or repel pests, or to regulate plant growth. It can be in the form of a liquid, powder, dust, granules, baits or a gas.

Pesticides can be grouped, and are usually given a special name, according to purpose. For example a weedicide or herbicide kills weeds or herbage, a bactericide - bacteria, a fungicide - fungi, a miticide - mites, an insecticide - insects, a larvicide - insect larvae (young stages), an ovicide - eggs of insects or mites.

A plant growth regulator speeds up, stops or otherwise changes normal plant growth.

A desiccant dries up plant leaves and stems, and a defoliant removes unwanted plant leaves without killing the whole plant immediately. Defoliants and dessicants make it easier to harvest certain crops - for example, cotton.

Pesticides range from common, everyday materials such as kerosene to complex chemical and biological agents. Some are relatively safe to handle and use but others are highly toxic to humans and non-target species.

Why Do We Need Pesticides?

We need to protect plants and animals that provide our food and fibre against weeds, pests and diseases which can destroy them, reduce their yields, and increase the cost of production.

Protection from pests involves a combination of mechanical biological and chemical controls. Although non-pesticide methods should always be considered first, in many cases chemical pesticides are the only effective and economical method of control. If pesticides were not used, crop yields could drop by as much as a third and food prices increase by 75 per cent.

Whats In a Pesticide?

Commonly, a pesticide has three main components which together are known as the formulation.

• The active constituent or ingredient kills the pest.
• The surfactant (which is like a deterent) helps the active constituent to disperse evenly over the target surface.
• The carrier stabilises the diluted product and aids application, coverage and retention of the applied pesticide.