BSPP News 31 Autumn 1997 - Online Edition

The Newsletter of the British Society for Plant Pathology
Number 31, Autumn 1997

Pesticides and Perspectives - a Personal View


Consumers in the UK and in other developed economies can now select from a previously unequalled range of food items. Apart from staples, and in addition to canned and frozen foods, an extensive range of fresh fruit and vegetables is available on an almost year round basis. In response to steadily increasing demand British growers have adopted an impressive array of innovative techniques as well as new plant varieties to increase yields and extend harvest periods. The limits of seasonality are being further challenged by the establishment of overseas sources of supply in both temperate and tropical regions together with efficient international transport green beans from Guatemala can be on UK supermarket shelves within 36 hours of being picked! Such efficiency is equally applicable to tropical fruits and vegetables in their turn provided that they are of the requisite quality.

The Role of the Supermarket

Supermarket chains have been instrumental in widening customer choice by offering a continuous supply of nutritious, palatable and blemish free produce at competitive prices. Such produce is often additionally packaged for customer convenience on the basis of uniformity of size, shape and colour. Rigorous attention to quality standards also ensure the absence of any trace of pest, disease or foreign body. These innovations have progressively reduced the need for discrimination, and hence the time spent, at the point of sale. One extension of this concept, ordering via the internet for subsequent home delivery is already under evaluation! It is paradoxical that the factors that have underpinned the elevation of customer satisfaction to such heights are being questioned by the customers themselves, or by their (sometimes self appointed) representatives. Concern over food security, still a matter of grave importance for 800 million undernourished people in the world, has been replaced by a preoccupation with food safety and the sustainability and environmental impact of food production. Although agrochemicals remain the major issue, concern extends to include fuels, fertilisers, nutrients, slurries, farm yard manure, irrigation water and the use of plastic sheeting as mulches or tunnels. In effect, the definition of food quality is being extended to include production methods.

A Historical Perspective

It was not ever thus. In the postwar decade characterised by shortages of all kinds, food security was a dominant political aim. As a consequence, government policy and research together with the products of the emergent agrochemical industry were highly focused on production. Together with increasing mechanisation these factors have underpinned fundamental changes in agricultural practice, significant reductions in the labour force, changes in the rural landscape which it must be admitted have not met with universal approval and an impressive record of increased production and falling costs. In the last 20 years agricultural productivity in the UK has risen by 1.5% per annum while producers' prices have declined by 4 5% per annum on the same basis. Over the same time period the UK land area used for the production of arable crops (including potatoes) and for horticulture (including orchard and soft fruit, outdoor vegetables and glasshouses) but excluding setaside has declined to some 4.5 million ha or 19% of the total. Additionally the volume and value of exports has increased significantly while our level of selfsufficiency has been maintained at about 75% of indigenous food and feed. Agrochemicals have played a significant role in this very positive record but continue to suffer from a negative public image fostered by some pressure groups and the need for "sound bites" rather than serious discussion by the media.

The Production Challenge

For farmers and growers pests, pathogens and weeds can impact adversely on activities at any stage in a crop cycle, reducing crop stand and vigour, prolonging vegetative growth, reducing yields in terms of both quantity and quality, complicating harvesting, imposing grading costs and causing postharvest losses. Resorting to chemical control measures whether preemptive such as seed dressings and protective sprays or curative in response to an infestation level results in an increase in variable costs (in broad terms the cost of chemical, spray additives and application).

In theory a farmer should be able to remain indifferent to pests and pathogens until the economic injury caused equals the costs of control. In practice the very high cosmetic and quality standards imposed on producers by supermarkets in response to customer demand and the economics of their operations can result in "zero tolerance" since a rejected crop will be sold at a heavy loss or may not be sold at all. In effect, reflected customer demand has driven farmers and growers into the adoption of the high input systems that are a source of public concern. This concern is apparently more highly focused on pesticide residues than on antibiotics, hormones and other food additives.

Statutory Controls and Perspectives

When taking decisions about crop protection, farmers and growers must operate within the statutory controls imposed by the Food and Environment Protection Act 1985, the Control of Pesticides Regulations 1986, the European Council Directive 91/414/EEC ( the Authorisation Directive) and the Control of Substances Hazardous to Health Regulations 1988. These regulations cover the transport, packaging, storage and use of crop protection agents and impose a requirement for training and competence for all involved.

It is my experience that the general public remain largely unaware of the stringent requirements of pesticide registration and the vast amount of data presented to the authorities on performance, toxicology (in particular the establishment of the no observable effect level or NOEL and its relationship to dietary intake) as well as environmental intake and fate. Many are also unaware that only about 70 of the 400 or so active ingredients registered in the UK leave detectable residues in produce when used according to directions. Surveillance also indicates that the vast majority of detected residues fall below the Maximum Residue Limit (MRL). It is an offence to circulate any produce which contains residues which exceed the MRL but it must be borne in mind that residues in excess of the MRL do not automatically imply a risk to health.


There is now in the UK a considerable body of scientific investigation aimed at developing and introducing a more holistic and sustainable approach to the production of wholesome food. As the variety and intensity of these efforts seem proportional to the number of acronyms which bespatter the literature, the umbrella term of integrated crop management must suffice. As a biologist who has learned the hard way that reliance on narrow approach to any crop protection problem is doomed to failure, and spectacular failure at that, I am wholeheartedly in favour of both the concept and the work. The driving force behind a considerable proportion of this work is a reduction in pesticide use.

If my preceding analysis is correct then the elimination or severe reduction of pesticide use without equally effective alternatives in place will result in reduced yields, an increased demand for arable land, a greatly expanded agricultural labour force, a considerable increase in management resources (in both skill and time), a decrease in quality and shelflife, poor product appearance and dramatically increased prices. I await outcomes with great interest, and in the conviction that the difficulties that will be encountered in will thoroughly vindicate the enormous contribution made to our wellbeing by the judicious use of pesticides.

John Fisher
Independent Consultant