Deaths
at Indian pesticides plant
Gharda Chemicals in India has closed down its new
chlorpyrifos plant in Lote, Maharashtra following an accident which left three
people dead and about 25 injured. The accident was apparently caused by a blown
gasket in a high-pressure reactor, which resulted in a release of acrylonitrile
gases.
Following the accident at the end of
August, all operations a the Lote site were halted and an investigation was set
up by the company and Indian authorities. Initial company reports suggest the
accident was caused by operator error.
Agrow,
216, 23/9/94.
Toxic
claim in Brazil
Brazil’s public prosecutors are seeking damages
from Rhóne-Poulenc after the dumping of 12,000 tonnes of toxic waste along the
coast between Rio and Sao Paulo. The prosecutors say that between 1966 and 1988,
2.6 tonnes of toxic residues including hexachlorobenzene (HCB) were removed
daily from the Rhône-Poulenc plant making pesticides and solvents in Cubatao.
Lorries then dumped their toxic cargo all over the coastal region. Drivers even
left some of it in banana groves telling the owners it was ‘good compost’.
Rhône-Poulenc claims that the degree of contamination found is not dangerous
and stems from general pollution in the area.
The
Guardian 27/10/94.
Cotton
problems in Pakistan
Since the early 1980s, there has been a major
increase in cotton production in Pakistan with a corresponding rise in the
uptake of chemical control — especially against insect pests. This extensive
use is linked with pest-resistance to some insecticide groups, an upsurge in
some pests due to the effects of broad spectrum chemicals on natural enemies and
an increase in the number of people poisoned by insecticides. The latter is a
particular problem. “It is a social matter which must be urgently
addressed,” according to Professor Graham Matthews of
Application techniques continue to be
extremely poor due to substandard equipment. With about 75% of cotton growers on
small farms, the knapsack sprayer will remain the main method of spraying.
“Contamination of the operator readily occurs during application as well as
prior to spraying when concentrate was spilt over the fingers, when mixing the
spray,” recalled Professor Matthews.
Leaf
curl virus — continuing threat
Over the last few years the problem of leaf curl virus has gradually
increased to such an extent that it may cause about 70% of damage to this
year’s cotton crop. The complexity of the cotton ecosystem means it is
difficult to attribute losses to a single factor, but the virus was the main
contributor to a US$2.4 billion loss to the 1993-94 crop which earns 65% of
Pakistan’s foreign exchange. There was optimism this season that despite the
unprecedented levels of virus infection the crop was withstanding the epidemic
well, due to the widespread use of tolerant varieties. However a late season
outbreak of Heliothis has resulted in yet another poor crop. “There is
optimism for the future, because new varieties at the stage of field trials are
showing immunity to the virus” said Dr Peter Markham of the John Innes Centre
at Norwich in the UK.
Leaf curl virus is spread by the insect
Bemisia tabaci, the tobacco, cotton or sweetpotato white-fly. Until 1967,
the virus was unknown in Pakistan. In 1988, 60 hectares were affected — today,
the area is near to one million ha. A number of factors have contributed to this
result. Since the late 1 960s there has been a steady increase in the use of
pesticides in an uncontrolled fashion. The overuse of both pyrethroids and
organophosphorous compounds has resulted in widespread resistance in several
insect pests. Cypermethrin. cyfluthrin, methamidophos and monocrotophos are now
ineffective against the whitefly. Some populations are also developing
resistance to endosulfan. Inefficient use has meant that 90% of the insecticide
misses the insect target. To compound these factors,
whitefly now build up earlier in the growing season which presents better
climatic conditions for the virus to develop. It is also thought that varieties,
chosen because of a greater cotton fibre content, may have been more susceptible
to leaf curl virus.
“Unfortunately we are lacking
sufficient data which would account for the spread of this virus, and for
example account for where the virus comes form each year. There are so many
inexplicable observations associated with this virus epidemic; it is difficult
to recommend satisfactory control strategies. We find fields of a highly
susceptible variety with no infection growing adjacent to a field of a tolerant
variety with a high level of infection. In some fields the infection is very
severe every year, while in other areas it may be variable from year to year,”
lamented Dr Markham. Temperature at the time of planting, planting dates, wind
and local farming practices all seem to influence the outcome of the epidemic.
Non-chemical
solutions
IPM techniques, including the search for resistant varieties, are being
sought to solve the leaf curl virus problem. Cultural controls generally in
cotton, such as uprooting at the end of the season to reduce survival of pink
boll-worm, are also of fundamental importance. Selection of a quicker maturing
variety integrates well with early uprooting. Avoiding the growing of okra near
cotton also reduces the incidence of pink and spotted bollworms. Cultural
techniques can also influence the conservation of natural enemies so the role of
areas of fodder sorghum and berseen need to be more fully investigated. These
measures may also help in the control of the virus. “Farmers need to adopt
improved application technology and be assisted with IPM field training in order
to improve adverse health and environmental impacts and to reduce losses to pest
attack,” concluded Professor Matthews.
For
more information contact: Professor Graham Matthews, Silwood Pest
Management, Imperial College, Ascot, Berks, SL5 7PY, UK. Dr Peter Markham, John
Innes Institute, Colney Lane, Norwich, NR4 7UH, UK
[This article first appeared in Pesticides News No. 26, December 1994, page 11]