Agriculture Reference
In-Depth Information
Chapter 4
Crop protection in organic agriculture
Deborah Letourneau*, University of California-Santa Cruz, USA, and Ariena van Bruggen,
Wageningen University and Research Centre, The Netherlands
*Prof Deborah Letourneau, Department of Environmental Studies, University of California, 214 College Eight, Santa Cruz
California 95064, United States of America. Tel: +1 831 459 2860, Fax: +1 831 459 4015, Email: dletour@ucsc.edu
Introduction
Organic farming systems are challenged by many of the same crop protection issues as conven-
tional farming systems. Approaches to crop protection in organic agriculture differ widely
among growers globally and regionally. At one end of the spectrum, organic growers use sub-
stitution-based approaches in large-scale operations to capture premium prices in a niche
market. At the other end, resource-poor farmers producing subsistence crops use, by default,
pest regulation tactics based on traditional knowledge. Organic growers at both ends of the
spectrum are less motivated by environmental and public health considerations than are those
growers that have formed the philosophical centre of organic agriculture movements in various
parts of the world. For these growers, organic agriculture differs fundamentally from conven-
tional agriculture, not in terms of the pest and disease challenges that face crop production or
solely in the range of tactics used by growers, but in the conceptual approaches that frame crop
management strategies.
Too often, descriptions of the conceptual approaches in conventional and organic agricul-
ture are overly simplified (Trewavas 2004). Conventional pest control can no longer be charac-
terised as the reliance on scheduled applications of broad-spectrum pesticides (biocides,
insecticides, fungicides, herbicides). Best practices in conventional agriculture incorporate a
wide range of tactics, including pest monitoring and judicious use and timing of selective pes-
ticides, selection of insect and disease-resistant cultivars, and cultural controls such as crop
rotation and crop residue destruction. By the same token, organic agriculture is more than
conventional agriculture minus synthetic fertiliser and pesticide inputs. While some organic
growers do simply substitute manure for fertiliser and botanically derived pesticides for syn-
thetic pesticides - more often, organic practices involve a wide range of soil management and
cropping practices that maintain ecosystem health and foster ecosystem services (Altieri 1986
1999, van Bruggen and Semenov 2000).
For the purpose of this chapter on pest and disease management, organic agriculture is
defined as plant and animal production systems managed with an emphasis on sustainable
and renewable biological processes: nutrients supplied at rates needed to maintain nutrient
balances through decomposition of nitrogen (N)-fixing green manures and plant or animal-
based soil amendments, and pest management relying heavily on promoting plant health, veg-
etation management and biological control. Curative pest treatments include application of
microbials, botanicals, soaps, oils and minerals and augmentative releases of predators; syn-
thetic fertilisers or pesticides are generally not applied, unless exemptions are granted.
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