Research and technology Knowledge

Posted June 1996

Plant protection and pesticides

Science and technology for sustainable development, Part 4


Part 1
Forest management and conservation

Part 2
Land and water development

Part 3
Protecting fisheries resources

Part 4
Plant protection and pesticides

Part 5
Sustaining small farm enterprises

Part 6
Post-harvest technology and food quality

Part 7

Part 8
Plant production

Since the beginning of agriculture pests have caused problems, but the coexistence of pest and crop plant had resulted in traditional farming systems that generally kept damage to a minimum. However, intensification, including changes of cultivars, crops and cultivation patterns, have often created conditions more favourable to pests. Migration or introduction of pests to new areas may also call for control where it was not previously needed. The classical example is grapes, where treatments are now required for diseases in Europe that were introduced from another continent in the last century.

Changes in cultivation and the use of new varieties as in rice production in Southeast Asia have changed the agricultural situation completely, in the process making pests much more difficult to control. Land shortage and lack of inputs have increased the speed of rotations and decreased fertility in the Sahel of Africa, leading to favourable conditions for the parasitic weed Striga. A relatively new development is the spread of noxious weeds (e.g. Imperata) that appear to be resistant to most herbicides.

Migratory pests have been the scourge of crops since times memorial (one of the ten plagues of Egypt were locusts). In the 1980s, population growth of the four species of locusts found in sub-Saharan Africa assumed threatening proportions for the first time in 50 years. The FAO Emergency Centre for Locust Operations was set up to coordinate the international control efforts. The campaign was successful. It revealed a need for new strategies which are being sought in an FAO/UNDP research programme on desert locust control.

Minimizing pest damage

Ways and means to protect crops from pests are many and varied. Numerous organisms have the capacity to become major pests but most of these are controllable by combinations of cultural measures, host plant resistance and biological control. Pesticides are used where these other control mechanisms do not keep pests below an acceptable level. For control of weeds, labour scarcity or cost has prompted a gradual shift from manual and mechanical means to use of chemicals.

Pesticide use has, however, led to a number of new problems: biological control agents may also be eliminated, or the pests may become resistant to the pesticide. Excessive or overly liberal use of pesticides may also harm human health and the environment. Lack of knowledge, risk-avoiding behaviour and aggressive sales techniques often result in a misuse or overuse of pesticides.

FAO promotes research to prevent and decrease pest damage. Such research covers the reduction of the pest population, the use of cultural methods, enhancement of host plant resistance and, where appropriate, the identification and use of biological control agents. Research to discover new pesticides, research on application techniques and research on the relationship between pesticides and the environment are also of major importance. An example of biological control is "the sterile insect technique" (SIT).

In promoting plant protection and pest management, FAO especially emphasizes the role of integrated pest management (IPM). One example of a recent successful project is the development and application of integrated pest control in rice growing in south and southeast Asia. Field trials were made to define appropriate IPM technology in farming areas of the participating countries. These trials involved the identification of natural enemies of the major insect pests, and the choice of effective methods of pest surveillance and of forecasting insect attack severity during the growing season.

Such projects vary in the level of science and technology required or used. Some serve to establish national or regional research capabilities while others stimulate the extension of appropriate methodologies to farmers. A major FAO-executed programme presently under development is the application of IPM in vegetable production. The Organization's work on all aspects of IPM is directly related to sustainable agriculture.

The International Plant Protection Convention covers the field of plant quarantine. FAO serves as the secretariat of the Convention and as an information exchange on pest distribution and pesticide legislation and regulations. The 1989 Conference of FAO recommended that work be done on harmonization of the principles of plant quarantine legislation, of the principles of scientific evidence for plant quarantine measures, and of plant quarantine procedures.

Pesticides: a code for distribution and use

An important recent development has been the adoption by the FAO Conference (1985) of an International Code of Conduct on the Distribution and Use of Pesticides, amended in 1987 to include the principle of prior informed consent. The pesticides industry, through the International Group of National Associations of Agrochemical Manufacturers (GIFAP), and UNEP in regard to the prior informed consent clause, agreed to assist FAO in the implementation of the provisions of the code. Environmental groups use the code as a yardstick to evaluate pesticide management in developing countries.

The code is supported by a set of guidelines prepared with the cooperation and advice of experts from FAO member countries. These guidelines cover such topics as registration and control (legislative and monitoring) of pesticides; efficacy data needed for registration; environmental criteria; residue data; labeling, packaging and storage; and disposal of waste pesticides and pesticide containers.

An activity complementary to the code is the provision of technical assistance to strengthen national and regional pesticide control schemes, to establish the necessary analytical facilities, and to give guidance on the safe and efficient use of pesticides.

In cooperation with WHO, FAO proposes maximum residue limits and tolerable levels of intake over time, based on toxicology data provided by governments and industry and reviewed by FAO/WHO expert groups. More than 150 different pesticides have been evaluated, resulting in the adoption by the Codex Alimentarius Commission of more than 2 000 maximum residue limits on specific commodities. Quality control standards have been prepared for 25 pesticide active ingredients. These standards are used by national governments in the formulation of their legislation and for establishing import controls. They have also found use in international trade.

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