Farming

How are pesticides used?

As little as necessary

Today's pesticides (or crop protection products) are used in grams rather than kilograms per hectare. They are less toxic, more target-specific and more biodegradable than ever before and are used with great care and precision.

The colossal investment involved is reflected in the price paid by farmers and growers and means that they are not cheap. Using more than is recommended or necessary is a waste few farmers can afford. In addition, unlike many of us, farmers actually live where they work. Their families, livestock and pets share their working environment. This gives them an additional incentive to make sure crop protection products are always stored, handled and disposed of safely.

Advice for farmers

Farmers and growers can call on a great deal of advice to help them choose the right crop protection. Many take advice from a qualified agronomist. Product labels also provide essential advice such as dose rates, varieties, timing of applications, details of the pests controlled, safety precautions and the time which must be left between spraying and harvest.

Increasingly too, threshold levels are being determined for the major weeds and insect pests. For example, for weeds such as cleavers, just a few plants per square metre will have a damaging effect on the crop, so spraying is essential. For others such as poppies, the number of plants that can be tolerated is much higher.

High-tech farming

The farmer can also call on technology, in particular computerised decision-support systems. These include global positioning satellite (GPS) systems to help map their fields in terms of yield performance, and sophisticated monitoring equipment such as potato blight monitors that track weather conditions and predict when blight is likely to strike.

These tools all help to make product application more and more precise. Research into Integrated Crop Management (ICM) systems is also contributing to the development of precision farming. A better understanding of the complex interactions between soil type, crop variety, climate and crop nutrition, means that pesticides can be applied at the very best time - and therefore at lower doses.

Product application: Just a spoonful of sugar?

So how is the product applied? Although some are applied as seed treatments, most are diluted in water and sprayed onto crops. This is not as easy as it might sound. If you were asked to spread a teaspoonful of sugar evenly over a large field you would probably think it is impossible. However, this is often what is required when a farmer applies crop protection products.

Precision is the key. Imagine a farmer applying a fungicide to a crop of wheat. The amount of active ingredient in the pack is stated on the label as 50%. The product is to be applied at a rate of 1 litre per hectare diluted in 200 litres of water. This means that every square metre of the field must receive 0.05 grams of active ingredient. Assuming there are 300 plants per square metre, each plant will receive just 0.00017 grams.