Challenges and recommendations for the development of cultural control of aerial oomycete-associated diseases in protected horticulture

A lack of available host resistance due to the emergence of novel plant pathogen isolates and restriction in the use of chemical control means that additional approaches should be considered as part of an integrated pest management (IPM) programme for the control of crop diseases. As each stage of the pathogen lifecycle is influenced by climatic conditions, so modification of the growing environment could be used to help prevent or control disease outbreaks in protected horticulture systems. This is particularly important in Controlled Environment Agriculture (CEA) where product marketing is often reliant on an absence of chemical crop protection products. This review examines the environmental factors affecting plant diseases in protected cropping and summarises the cultural control studies made in relation to manipulating these conditions with regard to disease management using a case study of aerial oomycetes. Aerial oomycete pathogens are responsible for a wide range of commercially important diseases in both protected and field horticultural production. They include the causal agents of downy mildews and some Phytophthora infections and can be rapidly spread via airborne spores. We also discuss the importance of interactions between environmental factors on pathogen biology, outline disease modelling studies which aim to aid outbreak prediction and provide recommendations for the generation and use of effective cultural control procedures in protected horticulture