On the Conceptual Basis of Crop Loss Assessment: The Threshold Theory

Zadoks, J.C.

doi:10.1146/annurev.py.23.090185.002323

Cited by 195 publications

(117 citation statements)

References 23 publications

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“…However sophisticated the model, which in EPIPRE is nothing more than a deterministic yes/no decision model, it must determine the 'action threshold' (Zadoks & Schein, 1979), where no just tops over into yes. The actual course of disease is of no interest to either the system designer or to the decision maker, except to determine whether or not the disease will pass the action threshold (Zadoks, 1985). The quality of a decision support system does not depend on the amount of underlying knowledge, but on the frequency of its usage and the profits made by using it.…”

Section: Field Monitoring Epipre's Comparative Advantage Is Its Fieldmentioning

confidence: 99%

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Simulation and systems management in crop protection

1991

Plant Growth Regul

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No part of this publication, apart from bibliographic data and brief quotations embodied in critical reviews, may be reported, re-recorded or published in any form including print, photocopy, microfilm, electronic or electromagnetic record without written permission from the publisher: Pudoc, P.O. Box 4, 6700 AA Wageningen, the Netherlands. Population models for fruit-tree red spider mite and predatory mites -R. Rabbinge Pests, disease and weeds have threatened crop production since man began agricultural activity. They are a nuisance to the farmer in every agricultural system, be it subsistence farming or the high input farming now practised in many parts of the Western world. Printed in the NetherlandsIn the last decade, pest and disease management have become accepted terms in crop protection. This is due both to a revolution in thinking and to a considerable increase in knowledge. The rather simplistic concept of destruction or total exclusion of a plant pest or disease has changed, and made way for the concepts of supervised control and pest and disease management. In agricultural systems, disease or pest outbreaks are no longer disasters which must be accepted, but are now manageable and manipulable phenomena. Intensive agriculture is developing into a technological rather than a biological activity.More and more techniques with well-understood effects have been developed and are beginning to dominate the less well-understood methods of biological control. This enables the farmer and his advisers to manage the agricultural system to meet a well-defined target, that of maximum economic return in the short term and sound agricultural practice in the long term.Crop protection is incorporated into a cropping system to manipulate the pathosystem of a crop in a way that prevents economic loss. Crop protection research is following a similar trend: the accent is changing from the 'scientific', to the 'technological'. Both types of research focus on crop protection. Scientific and technological activities are not considered to be qualitatively different, nor can an appeal be made to concepts of'pure' as opposed to 'applied' science. They are considered as points on a convenient spectrum that is defined in terms of the objectives and expectations of the practitioners.This development in crop protection research -from studying and describing effects to understanding, governing and manipulating cropping systems -has been made possible by an enormous increase in our knowledge of the prosesses of crop growth and crop production, and by an improved understanding of how crops behave and can be affected.Systems analysis and simulation have contributed considerably to this development by providing the insight which has led to crop management policies and techniques. Modern crop protection is a complicated affair in which risk, cost-effectiveness and environment must be considered. Genetic resistance, crop husbandry methods and weather determine the course of insect-pest outbreaks and disease epidemics. Pesticides are often...

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Section: Field Monitoring Epipre's Comparative Advantage Is Its Fieldmentioning

confidence: 99%

“…Procedures The effect of disease intensity on damage and loss (Zadoks, 1985) depends on the development stage of the crop. All calculations are based on the development stages described by the Decimal Code (Zadoks et al, 1974).…”

Section: How a Decision Is Madementioning

confidence: 99%

Simulation and systems management in crop protection

1991

Plant Growth Regul

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“…Supervised control is the dominant paradigm in tactical decision support in crop protection (Zadoks, 1985). The concept is based on maximization of returns on expenditure for chemical control, but applies also to other methods of pest management where proper timing is required.…”

Section: Introductionmentioning

confidence: 99%

Uncertainty and Tactical Decision Support in Winter Wheat Pest Management

Rossing

Daamen²,

Hendrix³

et al. 1994

Plant Production on the Threshold of a New Century

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ABSTRACT. Timing of chemical control of pests and diseases is a decision problem which consists of objectives, strategies, a model of the system, and decision criteria. 'Return on expenditure' and 'insurance' are generally applicable, potentially conflicting objectives of pest control. Uncertainty about the costs of different strategies of chemical control of cereal aphids (especially Sitobion avenae) and brown ruse (Puccinia recondita) in winter wheat is calculated with a deterministic model. Sources of uncertainty, which comprise estimates of initial state and parameters, future weather, and white noise, are modelled as random inputs.A widely used decision criterion in crop protection is the damage threshold, defined as the level of pest attack where projected costs of immediate control just equal projected costs of no control. No chemical control is the recommended action when the level of pest attack is below the damage threshold. It is shown that ignoring uncertainty leads to wrong recommendations.It is argued that a consultative decision support approach which emphasizes the consequences of strategies in terms of objectives, is more appropriate than a prescriptive approach which concentrates on applying decision criteria to find the 'optimal' strategy. A consultative framework is proposed in which strategies are analyzed in terms of 'return on expenditure' and 'insurance•.

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“…Injury may not necessarily cause damage, which is a deviation from the normal production of the plant. Damage in turn may not necessarily have an economic impact, called loss (Zadoks, 1985). For natural vegetation, the notion of loss, but not that of damage, may be ignored.…”

Section: Introductionmentioning

confidence: 99%

The function of plant pathogenic fungi in natural communities

Zadoks¹

1987

Disturbance in Grasslands

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On the Conceptual Basis of Crop Loss Assessment: The Threshold Theory

Cited by 195 publications

References 23 publications

Simulation and systems management in crop protection

Simulation and systems management in crop protection

Uncertainty and Tactical Decision Support in Winter Wheat Pest Management

The function of plant pathogenic fungi in natural communities

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