Pesticides and their effects on crop ecology

Proper training of workers a must to avoid accidents

By Dr. S.M. Alam, NIA, Tandojam
Oct 11 - 17, 1999

Agriculture is the mainstay of the economy of Pakistan. The climate and large variety of food and cash crops grown all over the country are very favourable for the multiplication of insect pests, diseases and weeds. The total annual loss caused by these agents is estimated to be over 30 to 35 per cent. Much of the damage to agricultural production can be prevented in the field as well as in storage, if timely and adequate plant protection measures are adopted by public and private agencies and farming community. It has been established that without plant protection measures optimum agricultural crop yield cannot be obtained even though the farmers may have used improved variety of seeds, fertilizers and enough water for irrigating the crops. Pesticides are and will continue to play, in the foreseeable future, the major role in protection of crops from the ravages of insect pests, diseases, weeds and rodents of the farmers field of the country.

Plant protection through pesticides is one of the major input costs in high cash crops of agriculture in Pakistan. The use of pesticides have brought positive results in boosting up food production and decreasing losses in yield of crops caused by various diseases and pests. Pesticides are dominant in Pakistan's agriculture and have become a farmer's compulsion. To achieve a higher crop output, the use of pesticides is necessary. In the country, there has been a persistent and steady increase in the use of pesticides from 665 tons in 1980 to 44,872 tons in 1998. Pakistan, unfortunately imports huge amount of pesticides involving nearly $100 million. Pesticides used in the country were introduced in early sixties. The high yielding crop varieties proved susceptible to various insect pests. Use of pesticides has become the key pest control procedure in the country and the negative impacts associated with pesticide use has begun to emerge over time which are alarming at the present moment. Despite the use of 2.5 million tons of pesticides worldwide, approximately 55% of potential crop production is lost to pests every year. In fact, the farmers are required to spray more pesticides with higher concentration every year to combat these increasing pest population. Pesticides play an important role in agricultural development. As our agriculture is in the process of development and extension, the use of pesticides is increasing day by day. According to Pakistan Agricultural Pesticides Association, the consumption of pesticides in Pakistan in recent years has increased several hundred times. Most of the pesticides are highly toxic. They may kill not only pest but also animals and human being at a higher dose. Agricultural workers, farmers and other persons dealing directly or indirectly with pesticides should not only be well informed about the effectiveness of various chemicals against insect pests, nematodes, fungi and weeds but they should also be well-acquainted with the potential health hazards involved during manufacture handling, formulating, application, storage and transport of these toxic materials. They should, therefore, be employed with great care and with proper knowledge.

In Pakistan where literacy is very low, their indiscriminate and improper use/spray could create and is creating multifarious hazards. Pesticides toxicity are of the toxic nature as acute, chronic, oral and dermal toxicity. The toxicity created by pesticides in environments are on pollution of air, soil and water. Polluted soil kills the nitrogen fixing bacteria earthworms, and other useful microbe hazards from residues of pesticides in the harvested crops killing of predators, parasites, honey bees, fish, birds and other wildlife etc. Some pesticides are both persistent and accumulative and are especially hazardous if they escape from the target area.

Small quantities of pesticides are used for household purposes, including the safe storage of food, especially the food grain. Pakistan being an agricultural country, the financial and the material loss of all the crops suffering to a greater extent from damage of pests, mites, insets, nematodes, rodents, fungi, bacteria, virus and from competition with weeds, to considerable extent. Pesticides are comprised of fungicides, bactericides, arboricides, acaricides, algicides, nematocide, zoocides, limacides, desiccants defoliants, antiseptics etc. All these formulations are used in the control of pest organisms.

Pesticides are no doubt poisons. They cause serious harm if they put in a wrong place or on the wrong plant or where the animals eat them. Proper education of workers and farmers in safe handling, storage and working practices may prevent some accidents and at the same time greatly reduce the number of illness resulting from carelessness or misuse. Indiscriminate use of pesticides should be avoided. Correct method and timing of application are also important in checking the environmental pollution. No specific detailed research has been conducted so far to study the impact of pesticide use over time, on crop ecology in Pakistan. Agricultural officials, though aware of the negative impacts of pesticides failed to check the increasing menace of pesticides. Due to faculty spray equipment and untrained operators, more than 95 per cent of pesticides, applied to crops, hits the non target areas and degrade the crop ecology. To avoid this pesticide wastage, the certified and annually tested spray equipment should be used. Well trained applicators/operators or registered technicians should only be allowed to handle and apply pesticides. For this purpose, farmers should be trained from time to time through public and private agencies.