The Challenges of Chemical Control of Plant Diseases

Abstract

Since the first fungicide, sulphur, was used to control powdery mildew on grapes, production of most crops has become dependent on the use of fungicides to avoid disease losses. In the late 1840s the Irish potato famine proved the necessity for chemical intervention to prevent human and economic disaster. Recently it has become increasingly difficult for growers to control crop diseases. Genetic resistance of crops towards diseases has been in many cases short-lived (for example cereal rusts), and GMOs have only limited success for disease control and acceptability. With more intensive cropping, new diseases have arisen which are devastating if not controlled, such as Asian Rust of soybean. In addition, new races and more aggressive pathotypes of diseases have arisen. All these changes require the rapid development of chemical control measures to prevent economic disaster, since reliance on genetic resistance and cultural techniques have been insufficient. Intensive use of chemical control measures has in turn led to its own challenges, including resistance to fungicides. The sustainable use of fungicides to prolong their effectiveness and usefulness to growers is key, and the implementation of resistance management strategies an essential part of this. Only if the long-term effectiveness of fungicides can be ensured will industry invest the money and resources required for their discovery and development, especially considering the high standards of today’s registration requirements. The Fungicide Resistance Action Committee (FRAC) and its network play a vital role in the design and support of these strategies.