Analysis of decision making in crop protection

Abstract

The crop protection decisions taken by a farmer are determined by four main factors: the farmer's objectives, his perception of past attack and the damage it can cause, the control measures available to him, and the decision rules by which he operates. In analysing the way in which these factors interact, the purpose of this paper is to increase our understanding of the crop protection decision problem and to show how an appreciation of the farmer's situation is important in designing successful research and extension programs. The paper is divided into two parts. In the first part, two classes of decision model are illustrated by means of case studies. For the economic threshold model, requiring specific information on pest attack and using conventional economic analysis, the potato cyst eelworm problem is used as an example. The prophylactic decision model, which uses information on the probability distribution of attack and relies more on decision theory techniques, is illustrated by reference to the problem of potato blight. It is recognised, however, that in many real life situations these decision models are not appropriate, the result of inadequate information, limited managerial ability, or extreme risk constraints. In this situation, farmers do not attempt to optimise but search for a crop protection strategy that is satisfactory, one that meets their objectives as well as their operational constraints. With this view of the farmer's situation, the second part of the paper concentrates on the way in which research and extension programs can improve it. Attention is focussed on the three methods of achieving this; by widening the range of control measures available, increasing the perception of relevant information, and by improving decision rules. In concluding, it is stressed that a successful reduction in a particular constraint to better decision making is only likely to be achieved where the measures taken are designed in the context of those constraints that remain.