Tackling
injudicious use of pesticides
INSECT
pests and diseases, the prime factors causing low
agricultural productivity, are mostly controlled by chemical
means. Indiscriminate use of pesticides is causing serious
environmental hazards. This can be minimised by a variety of
cultural and biological measures.
A large amount of foreign exchange is consumed in the import
of pesticides. Only during July-March, 2005-06, 17,900 and
36,000 tons of agricultural pesticides were imported.
These chemicals are not only high-priced inputs but are also
hazardous to the environment. These affect human health and
biological diversity and leave persistent residues in soil,
groundwater, and the food chain, thus exposing human
population to slow and cumulative poisoning. Poor spraying
techniques and over-use of chemicals has also led to the
pest becoming resistant to most of the available
insecticides.
Seeing their crops devastated by insects, and desperate to
salvage something from their losses, farmers have continued
to buy more toxic (and expensive) chemicals and to spray
more frequently, but with decreasing effectiveness. This all
necessitate a system to cut off the pesticide use to an
acceptable level, for this purpose some suggestions and
recommendations are as follows:
Integrated pest management (IPM) is the base of such a
system which deals with the systematic and effective use of
pesticides. The IPM is the integration of all practical pest
control methods in as compatible manner as possible to
maintain pest populations below the economic threshold. The
most beneficial and economically better control of all
diseases and insect pests can be achieved through IPM as
compared to any other single management practice, such as
pesticide application.
In any crop production system, IPM includes combining
cultural practices like appropriate variety selection, land
preparation, sowing dates, frequent field scouting,
biological control through natural predators, parasites and
pathogens; and selective and judicious use of insecticides
to keep insect and mite populations below economically
damaging levels. This pest management system is designed to
keep inputs at a minimum level while maintaining or
increasing production for maximum profit.
In addition, many other methods to avoid insect pressure can
be put in to practice. For example, the utilisation of
insect repellents, light traps, eradication of weeds from
the fields, spray of semi hot water (it also has been proved
to be good for insect control especially in case of mealy
bugs), spray of surf solution and spray of neem extract has
been effective to limit various insect populations to
curtail heavy production losses.
Management practices can also prove to be a useful tool to
avoid chemical solution to the disease problem. Integrated
Disease Management (IDM) should be applied to achieve this
objective to ensure high quality production. The IDM is
actually a combination of various cultural and chemical
control mechanisms. It may include the following principles:
Three to four years crop rotation with non-host crops.
Resistance is the most effective and economical means of
disease control. For some diseases, resistance is the only
effective control. Therefore, available disease resistant
varieties should be planted where possible.
Efforts should be made to obtain disease-free seed for
transplantation or these should be properly dressed with
proper fungicides. Soil fumigation is expensive and
potentially dangerous for inexperienced applicators, but
increases yield, earliness, and controls soil- borne
diseases. However, row fumigation may be economically
feasible mostly for vegetables.
Change in planting time is recommended to avoid diseases in
various cases. For example, cultivation of early sowing and
early maturing varieties are recommended for the control of
rust in wheat. Excessive irrigation as well as shortage of
irrigation favours spread and development of many diseases.
Therefore, the crops should be irrigated properly.
Proper and judicious use of fertilisers especially
nitrogenous fertilisers should be carried out along with
potassic fertiliser. Mostly the weeds serve as alternate
hosts or sources of infection for virus diseases. Therefore,
effective weed control practices should be utilised in and
around the crops.
Insects are major source of transmission of viruses and
bacterial diseases. Therefore, insects must be controlled
when warranted in and around the crops.
Scouting allows for early detection of all pests and
diseases so that timely management practices can be
implemented. Plantings should be scouted regularly (at least
once per week), for assessment of the effectiveness of
management programmes already implemented.
Appropriate use of copper sprays is also useful in reducing
foliar diseases caused by bacteria. The diseases are more
difficult to control once established; hence timing of the
first spray is critical. The first spray should be made
before symptoms appear where diseases are anticipated or
shortly after symptom appearance.
Many of the pathogens survives in and on the plant debris or
pruned parts of plants or trees, therefore these should be
incorporated into the soil by ploughing or disking after
harvest to hasten decomposition.
The capacity of IDM strategies as an effective component of
IPM system may give a hope to the growers for the benefit of
themselves as well as for the nature. Their effectiveness in
controlling specific diseases could be learnt through
regular study and observation.
Courtesy: The Dawn
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