As a result of the green revolution, the use of yield-increasing inputs such as fer- tilizer and pesticides became a matter of course in irrigated rice farming in Southeast Asia. Pesticides were applied liberally, both as a guarantee against crop failure and as a means of fully utilizing the existing yield potential of the crops. However, since outbreaks of pests, such as the brown planthopper (BPH) or the tungro virus, continued to occur despite the application of chemicals, a change of approach began to take place. It is now being realized more and more in Southeast Asia that crop protection problems cannot be resolved solely by the application of chemicals. In the past several years, increasing efforts have there- fore been made to introduce, as a first step, supervised crop protection, leading gradually to integrated pest management (Kranz, 1982). Although the crop protection problems naturally differ in the different devel- oping countries in Southeast Asia, the economic situation prevailing in these countries can nevertheless be regarded as an important common determinant: pesticide imports use up scarce foreign currency and thus compete with other imports essential to development. For the individual rice farmer, the problem is basically the same: his cash funds are limited and he must carefully weigh whether to use them for purchas- ing pesticides, fertilizer or certified seed. In view of this constraint, it is becom- ing necessary to abandon the purely prophylactic, routine calendar spraying and instead, employ critically timed and need-based pesticide applications.

Table of Contents:
1 Background Conditions and Current Situation in Irrigated Rice Farming.- 1.1 General Cropping Conditions.- 1.2 Organization of Extension and Crop Protection Services.- 1.2.1 Organizational Structure of the General Extension Service.- 1.2.2 Organizational Structure of the Crop Protection Service.- 1.3 The Major Pests of Rice.- 2 Assessment of Crop Loss Due to Pests in Irrigated Rice Farming.- 2.1 Assessment of Crop Loss in the Philippines.- 2.1.1 Official Pesticide Evaluation Trials.- 2.1.2 Trials Concerning Higher Levels of Crop Protection Intensity.- 2.1.3 Trials Concerning Alternative Pest Control Methods.- 2.1.4 Trials Conducted by the Author.- 2.1.5 Summary of Crop Loss Assessments in the Rice Crop of the Philippines.- 2.2 Crop Loss Assessments by Means of Damage Coefficients.- 2.2.1 Methodology.- 2.2.1.1 Selection of Exogenous Variables.- 2.2.1.2 Selection of Endogenous Variables.- 2.2.1.3 Determination of the Potential Yield.- 2.2.2 Selection of the Correct Type of Function.- 2.2.3 Presentation of Available Data.- 2.2.3.1 Data for Non-Resistant Varieties.- 2.2.3.2 Data for Resistant Varieties.- 2.2.4 Sorting of Available Data.- 2.2.5 Determination of Damage Coefficients by Means of Simple and Multiple Regression Analysis.- 2.2.5.1 Greenhouse and Cage Trials.- 2.2.5.2 Insecticide Trials.- 2.2.5.3 Results Obtained for Resistant Varieties Using Data from Field Trials.- 2.2.5.4 Summarizing Assessment of Findings and Comparison with the Relevant Extension Recommendations.- 2.2.6 Computation of Crop Losses on the Basis of Infestation Data and Damage Coefficients.- 2.2.6.1 Analysis of Pest Development Over Time.- Non-Resistant Varieties.- Resistant Varieties - Untreated Plots.- Resistant Varieties - Observation Stations.- 2.2.6.2 Results of Crop Loss Computations.- Non-Resistant Varieties.- Resistant Varieties - Untreated Plots.- Resistant Varieties - Observation Stations.- Summarizing Evaluation of Crop Loss Computations.- 3 Bases of Micro-Economic Analysis of Chemical Crop Protection Measures.- 3.1 Definition of the Concept of Economic Thresholds.- 3.1.1 Entomologists' Definition.- 3.1.2 Economists' Definition.- 3.1.3 Relation Between Economic Damage Threshold and Control Threshold.- 3.1.3.1 Relation Between the Two Threshold Levels for Rice Pests.- 3.1.4 Consideration of Mixed Infestations.- 3.1.5 Dynamic Aspects.- 3.1.6 Summary.- 3.2 Methods of Calculation for Economic Analysis of Crop Protection Measures.- 3.2.1 Analysis of Production Functions.- 3.2.2 Cost and Returns Analysis.- 3.2.3 Systems Analysis Approach.- 3.2.3.1 Bio-Economic Simulation Models.- 3.2.3.2 Decision Theoretic Approach.- Pay-Off Matrix.- Theoretical Decision Rules.- Practical Decision Rules.- 3.2.3.3 Summary and Comparison.- 4 Alternative Crop Protection Strategies in Irrigated Rice Cultivation: Comparison and Evaluation by Means of a Computer Model.- 4.1 Description of the Model.- 4.2 Model Assumptions.- 4.2.1 Control Strategies.- 4.2.1.1 Strategies for Granules.- 4.2.1.2 Strategies for Sprays.- 4.2.1.3 Strategies Used by Farmers.- 4.2.1.4 Extension Recommendations.- 4.2.1.5 Other Strategies.- 4.2.2 Effectiveness of Control.- 4.2.2.1 Strategies for Granules.- 4.2.2.2 Strategies for Sprays.- 4.2.2.3 Strategies Used by Farmers.- 4.2.2.4 Extension Recommendations.- 4.2.2.5 Other Strategies.- 4.2.3 Control Costs.- 4.2.3.1 Pesticides.- 4.2.3.2 Labour.- 4.2.3.3 Interest.- 4.2.3.4 Cost of Additional Harvest.- 4.2.4 Socio-Economic Conditions in the Three Investigation Areas.- 4.2.4.1 Farm and Family Size.- 4.2.4.2 Land Tenure.- 4.2.4.3 Costs and Returns.- 4.2.4.4 Potential Yield.- 4.2.4.5 Crop Prices.- 4.2.4.6 Farm Income Situation and Necessary Minimum Yields.- 4.2.4.7 Liquidity Position.- 4.2.4.8 Opportunity Costs of Cash.- 4.3 Results of the Model Computations.- 4.3.1 Results Computed for the Nueva Ecija Area.- 4.3.1.1 Model Assumptions.- 4.3.1.2 The Optimum Strategy.- Comparison Between Optimum Strategy and Farmers'1 Background Conditions and Current Situation in Irrigated Rice Farming.- 1.1 General Cropping Conditions.- 1.2 Organization of Extension and Crop Protection Services.- 1.2.1 Organizational Structure of the General Extension Service.- 1.2.2 Organizational Structure of the Crop Protection Service.- 1.3 The Major Pests of Rice.- 2 Assessment of Crop Loss Due to Pests in Irrigated Rice Farming.- 2.1 Assessment of Crop Loss in the Philippines.- 2.1.1 Official Pesticide Evaluation Trials.- 2.1.2 Trials Concerning Higher Levels of Crop Protection Intensity.- 2.1.3 Trials Concerning Alternative Pest Control Methods.- 2.1.4 Trials Conducted by the Author.- 2.1.5 Summary of Crop Loss Assessments in the Rice Crop of the Philippines.- 2.2 Crop Loss Assessments by Means of Damage Coefficients.- 2.2.1 Methodology.- 2.2.1.1 Selection of Exogenous Variables.- 2.2.1.2 Selection of Endogenous Variables.- 2.2.1.3 Determination of the Potential Yield.- 2.2.2 Selection of the Correct Type of Function.- 2.2.3 Presentation of Available Data.- 2.2.3.1 Data for Non-Resistant Varieties.- 2.2.3.2 Data for Resistant Varieties.- 2.2.4 Sorting of Available Data.- 2.2.5 Determination of Damage Coefficients by Means of Simple and Multiple Regression Analysis.- 2.2.5.1 Greenhouse and Cage Trials.- 2.2.5.2 Insecticide Trials.- 2.2.5.3 Results Obtained for Resistant Varieties Using Data from Field Trials.- 2.2.5.4 Summarizing Assessment of Findings and Comparison with the Relevant Extension Recommendations.- 2.2.6 Computation of Crop Losses on the Basis of Infestation Data and Damage Coefficients.- 2.2.6.1 Analysis of Pest Development Over Time.- Non-Resistant Varieties.- Resistant Varieties - Untreated Plots.- Resistant Varieties - Observation Stations.- 2.2.6.2 Results of Crop Loss Computations.- Non-Resistant Varieties.- Resistant Varieties - Untreated Plots.- Resistant Varieties - Observation Stations.- Summarizing Evaluation of Crop Loss Computations.- 3 Bases of Micro-Economic Analysis of Chemical Crop Protection Measures.- 3.1 Definition of the Concept of Economic Thresholds.- 3.1.1 Entomologists' Definition.- 3.1.2 Economists' Definition.- 3.1.3 Relation Between Economic Damage Threshold and Control Threshold.- 3.1.3.1 Relation Between the Two Threshold Levels for Rice Pests.- 3.1.4 Consideration of Mixed Infestations.- 3.1.5 Dynamic Aspects.- 3.1.6 Summary.- 3.2 Methods of Calculation for Economic Analysis of Crop Protection Measures.- 3.2.1 Analysis of Production Functions.- 3.2.2 Cost and Returns Analysis.- 3.2.3 Systems Analysis Approach.- 3.2.3.1 Bio-Economic Simulation Models.- 3.2.3.2 Decision Theoretic Approach.- Pay-Off Matrix.- Theoretical Decision Rules.- Practical Decision Rules.- 3.2.3.3 Summary and Comparison.- 4 Alternative Crop Protection Strategies in Irrigated Rice Cultivation: Comparison and Evaluation by Means of a Computer Model.- 4.1 Description of the Model.- 4.2 Model Assumptions.- 4.2.1 Control Strategies.- 4.2.1.1 Strategies for Granules.- 4.2.1.2 Strategies for Sprays.- 4.2.1.3 Strategies Used by Farmers.- 4.2.1.4 Extension Recommendations.- 4.2.1.5 Other Strategies.- 4.2.2 Effectiveness of Control.- 4.2.2.1 Strategies for Granules.- 4.2.2.2 Strategies for Sprays.- 4.2.2.3 Strategies Used by Farmers.- 4.2.2.4 Extension Recommendations.- 4.2.2.5 Other Strategies.- 4.2.3 Control Costs.- 4.2.3.1 Pesticides.- 4.2.3.2 Labour.- 4.2.3.3 Interest.- 4.2.3.4 Cost of Additional Harvest.- 4.2.4 Socio-Economic Conditions in the Three Investigation Areas.- 4.2.4.1 Farm and Family Size.- 4.2.4.2 Land Tenure.- 4.2.4.3 Costs and Returns.- 4.2.4.4 Potential Yield.- 4.2.4.5 Crop Prices.- 4.2.4.6 Farm Income Situation and Necessary Minimum Yields.- 4.2.4.7 Liquidity Position.- 4.2.4.8 Opportunity Costs of Cash.- 4.3 Results of the Model Computations.- 4.3.1 Results Computed for the Nueva Ecija Area.- 4.3.1.1 Model Assumptions.- 4.3.1.2 The Optimum Strategy.- Comparison Between Optimum Strategy and Farmers' Strategies.- 4.3.1.3 Benefit of the Warning Service.- 4.3.1.4 Benefit of Control Thresholds.- 4.3.1.5 Benefit to Be Derived from Infestation Forecasts.- 4.3.2 Results Computed for the Camarines Sur Area.- 4.3.2.1 Model Assumptions.- 4.3.2.2 The Optimum Strategy.- Comparison Between Optimum Strategy and Farmers'Strategies.- 4.3.2.3 Benefit of the Warning Service.- 4.3.2.4 Benefit of Control Thresholds.- 4.3.2.5 Benefit of Infestation Forecasts.- 4.3.3 Results Computed for the Iloilo Area.- 4.3.3.1 Model Assumptions.- 4.3.3.2 Optimum Strategy and Comparison with Farmers'.- 4.3.3.3 Benefit of the Warning Service.- 4.3.3.4 Benefit of Control Thresholds.- 4.3.3.5 Benefit of Infestation Forecasts.- 4.3.4 Comparative Assessment of Model Results for the Three Investigation Areas.- 4.3.4.1 Economics of Crop Protection Measures.- 4.3.4.2 Benefit of Information Improvement.- 4.3.4.3 Realizability of Strategies from the Point of View of the Individual Farm.- 4.3.5 Possibilities and Practicability of the Control Threshold Concept.- 4.3.5.1 Farmers' Methods of Pest Observations and Decision Criteria.- 4.3.5.2 Farmers'Ability to Interpret Infestation Situations.- 4.3.5.3 Economic Benefit of Currently Existing Control Thresholds.- 4.3.5.4 Required Reliability of Control Thresholds and Effectiveness of Control Based on Thresholds.- Increasing the Effectiveness of Control.- 4.3.5.5 Possibilities of Improving Threshold Values.- 5 Conclusions.- 5.1 Technical Progress in Control Strategies.- 5.2 Improvement of the Information Basis.- 5.3 A New Basic Concept of Crop Protection.- References.