and Integrated Pest Management - part - usaid

PESTICIDE RESIDUES IN THAILAND
N. Tayaputch
Division of Agricultural Toxic Substances
Department of Agriculture, Bangkok 10900, Thailand
Pesticides are now used more extensively in crop protection in almost every
country in Southeast Asia. Tropical areas are generally characterized by high
temperature, precipitation, and humuidity. This condition permits the continuous
presence of certain insects and diseascs, which pass through more generations
than in teinperate climates. Crop losses and reduction in productivity vary from
year to year and region to region, but an average of approximately 15-30% of
annual crop produce is lost to insects, diseases, and weed competition. Plant
protection measures, mainly with the use of chemical pesticides, are regularly
applied to crops, especially those which give substantial returns. The results
fron pesticide usage have generally been economic, effective, and convincing.
But after years of intensified use of pesticides, ecological shifts in insects and
diseases, increasing costs of plant protection, resistance to pesticides, pesticide
residues, environmental pollution, and pesticide poisoning have created serious
problems.
PE.STICIDE USE IN THAILAND
Thailand, which is a major food exporter, has the same problems as other
countries in the region concerning pe:iticide management. The major food crops
comprise rice, cassava, maize, etc., and have been under pest infestations for
many years. Pesticides, including herbicides and fungicides, have been employed
for pest control purposes using a number of application techniques. More than
60% of pesticides in Thailand are applied for the control of rice, cotton, and
vegetable pests. The rate of consuniption of pesticides has increased rapidly over
the past twenty years; the quantity of pesticides imported between 1976-1985 are
show, a inFigure 1.
The pesticides imported into Thailand during the early years were in the
form of finished products. Technical grades of active ingredients were
subsequently imported and formulated locally.
One of the problems associated with pesticide effectiveness is the low
quality of the pesticides sold in the market in Thailand. A survey was done by
the Division of Agricultural Toxic Substances in 1983 on 373 randomly selected
pesicide formulations. These were collected from farmers and markets, and then
analyzed for active ingredients. The results showed that only 56% of the
samples had the active ingredients correctly labeled. The other 44% of the
samples included about 5% of compounds entirely different from what was
claimed on the labels. The problem of falsified products needs to be improved
by strong enforcement of the pesticide regulations, because not only will it lead
to failure in pest control, but will create residue problems later on.