The 800 plus pages of Crop
Production and Crop Protection attempt the mammoth task of estimating
current potential levels of crop production, actual crop losses and
expected crop losses in the absence of crop protection. While the whole
spectrum of crop protection agents, methods and strategy is discussed,
only chemical pesticides are quantified in terms of cost, use and effect
and are the main plank in the book’s general argument of economic
indispensability of crop protection. As a follow on some 30 years later
from HH Cramer’s book Plant Protection and World Crop Protection
published in 1967 which is used as a benchmark for crop areas, yields,
production levels and losses (actual and projected) it offers an insight
into how the crop protection scene has changed over the last three
decades.
Early chapters on population growth, agricultural
production and food supplies emphasise the need to ensure access to food
and adequate nutrition for the world’s population. Predictably, perhaps,
the chapter on ‘Crop protection—past and present’ offers a detailed
account of the development of chemical control with exhaustive lists of
all the chemical groupings of insecticides, fungicides and herbicides with
only a short mention on pheromones which are classed as a type of
insecticide. The potential of biological control agents is generally
played down by claiming “that their use will be limited to niche
situations like the control of soil-borne diseases and control of insect
pests showing resistance to synthetic products”—this is certainly not
true today, if it ever was.
The meat of this book is in its middle 600 pages which
cover estimated crop losses by world, region and individual country for
rice, wheat, barley, maize, potatoes, soybeans, cotton and coffee. The
exercise provides exhaustive detail for each crop for yields, production
levels, area grown, actual losses, projected losses without crop
protection and a comparison with Cramer’s estimates given some 30 years
ago. The authors acknowledge the complexities and interactions within the
crop ecosystem aggravated by chemical inputs and the resulting
difficulties in drawing conclusions. It is in this area where it is
difficult to divorce the pesticidal effect of a chemical from other
factors that problems arise.
In rice for instance estimates indicate greater
percentage losses and higher actual yields since 1967, both of which are
attributed to more intensive production. The authors suggest the 48.6% of
attainable yield achieved would have slumped to just 17.6% without crop
protection. Pests are therefore taking a bigger slice of massively
increased yields (thanks to the plant varieties and agricultural
techniques of the Green Revolution) and this research maintains they have
only been prevented from taking almost all by the use control agents
(mainly chemical).
Nevertheless rice was grown for thousands of years and
evolved a delicate equilibrium with pests (mostly insects) before chemical
pesticides were used. The success of the FAO Inter-Country Rice Programme
is not mentioned (see p.3), nor is the evidence that intensive insecticide
use in rice has led to reduced yields and pest resistance and resurgence.
In the chapter on coffee losses much is made of the
continuing central role of copper fungicides in the control of foliar and
fruit diseases such as coffee leaf rust and coffee berry disease. Copper,
though the first recognised and first commercially used fungicide, is one
of the most difficult to pin down in terms of effect, especially in
coffee—it controls fungal and bacterial pathogens, acts as crop
micronutrient with an established ‘tonic’ effect in coffee but is
claimed to disrupt soil fertility in estates where copper has been used
over many years. Sustainable control of pests by pesticides in coffee has
not been demonstrated.
In assessing crop losses from pests in cotton it is
said: “In view of the high potential losses, it does not seem feasible
to grow cotton without protection and without agrochemicals especially for
insect control”. This is an uninformed view—many articles in Pesticides
News and the Pesticides Trust [now PAN UK] publication, The Cotton Reader,
demonstrate the contrary. It contrasts yields under a regime of intensive
pesticide use only with estimates of crop losses on the basis that no
other form of pest control is used, and only at the end of the book is
there a recognition of the contribution of other aspects of crop
management to pest control.
Two conclusions stand out. The first is that the
consumption of crop protection products has increased from US$ 900 million
in 1960 to more than US$ 26,000 million in 1990 (figure adjusted for
inflation) and the second is that “In the last few decades, crop
protection measures have not conspicuously reduced relative crop losses in
any of the crops investigated.”
From the outset the book acknowledges that shortfalls
in food availability will become increasingly acute in the developing
world where crop losses are highest (as a proportion) to actual yields.
Will these farmers come to rely increasingly on purchased inputs,
particularly fertilisers and crop protection products? Or in the year of
the World Food Summit, will steps be taken to improve access to food and
to promote food security using sustainable production methods?
As a source of facts and figures on areas, production
and crop losses in some of the world’s major crops the book is probably
unrivalled. The premises are too narrow however to support the argument
for a continuing or accelerated use of crop protection chemicals. What is
needed is a similar work taking into account results from integrated crop
management systems and alternative methods of pest control—and in a
manner that costs the indirect externalities of pesticides use.
E-C Oerke, H-W Dehne, F Schonbeck
and A Weber, Crop Production and Crop Protection, Elsevier PO Box 211,
1000 AE Amsterdam, The Netherlands, 1994, 808pp.
Terry Mabbett is an independent
writer on crop protection issues.
[This article first appeared in Pesticides News No. 31,March 1996, page 16]