5 Pest and disease control The 20th century saw the development of a multitude of chemicals such as fertilisers, pesticides and growth stimulants to aid the modern farmer. These have greatly increased overall yields, but unfortunately have created new problems | .5 Pest and disease control The 20th century saw the development of a multitude of chemicals such as fertilisers pesticides and growth stimulants to aid the modern farmer. These have greatly increased overall yields but unfortunately have created new problems including Reliance of farmers on expensive chemicals Health concerns regarding the use of such chemicals Contamination of the environment Pests and diseases need not be seen as a problem if the numbers or extent of infestation is fairly low and the amount of damage is minor. For many crops particularly those grown by organic means some small level of pest and disease damage may be acceptable. However pest and disease damage infestation can render some produce virtually worthless as it cannot be sold at a fair price. It would be difficult for most farmers to completely stop using chemicals but it is possible to significantly reduce dependence on them. Nature has provided a whole range of methods to control pests and diseases without the side effects that artificial chemicals have. The main point to remember about natural control methods is that they rarely achieve the same degree of control as some conventional chemical methods. Pest management and systems thinking One important concept of sustainable agriculture is that it takes a holistic approach to the entire farm system. Instead of conventional agricultural practices where for example a specific chemical is used to almost completely eradicate a certain pest or disease sustainable agriculture dictates a much broader-based approach. Cropping systems may be designed so that rotation reduces the need for chemical spraying. Chemical spraying may also be minimised by choosing disease-resistant varieties and by growing crops in areas where pests find it difficult to survive on that crop. The downstream effects and total system cost of that chemical spray are taken into account. Certain levels of pests and diseases 78 Sustainable Agriculture may be acceptable in a
