Agrometeorology and plant disease management: a happy marriage

Abstract

Many plant disease outbreaks are triggered by suitably warm temperatures during periods of leaf wetness. Measurements or estimations of leaf wetness duration provided by Agrometeorologists have allowed Plant Pathologists to devise weather timed spray schemes which often reduce the number of sprays required to control plant diseases, thus lowering costs and benefitting the environment. In the near future, tools such as numerical weather models with small grid spacings, and improved weather radar, are expected to reduce the need for tight networks of surface observations. The weather models will also provide growers with forecast warnings of potential upcoming disease outbreaks, which will further enhance the contribution of agrometeorology to plant disease management. Key words: leaf wetness duration, temperature, disease warning systems AGROMETEOROLOGIA E MANEJO DE DOENÇAS DE PLANTAS -UM CASAMENTO FELIZRESUMO: A disseminação de muitas doenças de plantas é influenciada por condições favoráveis de temperatura durante o período de molhamento foliar. As medidas e estimativas da duração do período de molhamento foliar fornecidas pelos Agrometeorologistas têm permitido aos Fitopatologistas dar alertas sobre a necessidade de pulverizações com base nas condições meteorológicas, o que normalmente reduz o número de aplicações para o controle de doenças, resultando em menor custo de produção e menor contaminação do ambiente. Em um futuro próximo, ferramentas como os modelos numéricos de tempo, com alta resolução espacial, e os radares meteorológicos mais avançados, deverão reduzir a necessidade de redes de observação meteorológica de superfície mais densas. Os modelos meteorológicos também possibilitarão a previsão de disseminação potencial das doenças de plantas, o que irá aumentar ainda mais a contribuição da agrometeorologia para o controle fitossanitário mais racional. Palavras-chave: duração do período de molhamento, temperatura, sistemas de alerta fitossanitárioThe dependence of many plant disease outbreaks on weather conditions has been known to growers for a very long time. This dependence, and the emergence of Agrometeorology as a scientific discipline in the second half of the 20 th century, has led to some excellent collaborative research between agrometeorologists and plant pathologists. This point of view highlights some of the successes and lessons learned in these collaborations, and looks into the future of Agrometeorology's role in plant disease management.The key weather variables that trigger many plant disease outbreaks are temperature and moisture. Temperature affects all phases of plant disease whereas moisture is important for the infection process (germination and penetration) and release of spores. Very often, the moisture variables involved are relative humidity (RH), leaf wetness duration (LWD) or rainfall (R). When duration of high RH is the key moisture variable, as with some mildew diseases, the job of providing data is facilitated by routine measurements of RH and R at weather stati...

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