ABSTRACT
The types of defence which can be utilised in attempts to control the unwanted organisms may be conveniently grouped under four headings: dealing with statutory, husbandry, biological, physical and chemical strategies. Husbandry techniques may also be used to modify the environmental conditions close to the soil surface to the disadvantage of the enemies of crops and stock. The damage caused by pests and diseases is not limited to the production phase, but may occur with even greater effect during the period of storage. Within food or fodder stores, the correct adjustment of the physical environment is an essential factor in reducing losses. The familiar structure of agriculture is the concentration of the plants and animals needed by man into compact areas where they can be conveniently managed, and from which it is hoped that predators and competitors can be excluded.
