Cultural Practices and Infectious Crop Diseases

The development of a crop, and therefore its health, is always the result of interplay between biological and environmental factors, as influenced by human agency. In other words, crop health is a highly complex affair. This book is concerned with only one group of agents affecting crop health, the pathogens, and not with animal pests or direct effects of physiological or weather factors. Even within this one group, however, the interaction of causal agents with environmental and biotic factors is highly complex. No less complex is the effect of cultural practices on the crop and its health. There is probably no major practice that does not affect diverse facets of crop growth, which in turn affects crop/pathogen relationships. Thus tillage se quentially affects depth and rate of root development, hence nutrient uptake, hence general plant size and habit as well as crop climate and crop susceptibility. Irri gation affects all these parameters, and facilitates crop growth under diverse macro climatic conditions, with all the ensuing implications for disease development. In this book an attempt is made to superimpose one set of complexities, the cul tural practices, on another such set, crop health. This may seem overambitious, not to say foolhardy, unless we remember that it has been done by farmers, consciously or unconsciously, ever since the beginnings of agriculture. We are here chiefly try ing to rationalize traditional practices, review modern research on the development of further practices, and assess the place of the latter in integrated disease control.

The development of a crop, and therefore its health, is always the result of interplay between biological and environmental factors, as influenced by human agency. Thus tillage se quentially affects depth and rate of root development, hence nutrient uptake, hence general plant size and habit as well as crop climate and crop susceptibility.

1 Climate, Cropping and Crop Disease.- 1.1 Agro-Ecosystems, the Cultural Practices They Have Generated, and the General Impact of Such Practices on Crop Disease.- 1.2 Microclimate and Crop Climate.- 1.3 The Collective Approach to Disease Control: Epidemiological Considerations and the Role of Cultural Practices in Regional Management of Inoculum.- 1.4 Soil, Soil Microbiota, and Soil-Borne Disease.- 1.5 Stress, Strain and Predisposition.- 1.6 Crop Age, Injury and Disease on Leaf and Fruit, with Special Reference to Disease in the Ageing Crop.- 1.7 Weeds and Crop Disease.- 2 Major Cultural Practices and Their Effect on Crop Disease.- 2.1 Cost/Benefit and Risk Assessment and the Complexity of Multiple Choice in Pest Control Decisions on the Farm.- 2.2 Sanitation.- 2.3 Crop Sequence.- 2.4 Soil Amendments and Mulches.- 2.5 Tillage.- 2.6 Crop Nutrition.- 2.7 Moisture Management in Non-Irrigated Crops.- 2.8 Irrigation.- 2.9 Rate of Sowing and Planting, and Density of Stand.- 2.10 Sowing and Planting Dates and Manipulation of Flowering and Fruiting Periods.- 2.11 Harvesting Dates and Practices.- 2.12 Planning to Minimize Influx of Air- or Vector-Borne Inoculum to Neighbouring Crops.- 2.13 Pruning and Grafting.- 2.14 Effects of Physical Barriers on Crop Infection and of Optical Means on Virus Vector Control.- 3 Interactions Between Cultural Practices, Resistance Breeding, and Application of Chemicals: Integrated Control.- 3.1 Keep Inoculum Out - by Any Available Means.- 3.2 Prevent Multiplication and Spread of Inoculum.- 3.3 The Proper Place for Cultural Practices in Integrated Disease Control.- 3.4 Profit in Fungicide Applications, as Related to Cultural Factors.- 3.5 Cultural Practices and the Use of Herbicides and Physiologically Active Chemicals.- 3.6 Hop Wilt in England:Success of Integrated Control.- 3.7 Some Thoughts on the Future of Integrated Disease Control and its Components in World Crop Production.- French, German and Spanish Translation of Some of the English Terms Used in this Book.- References.- Pathogen Index.