Managing grey mould on raspberry grown under protection without use of fungicides during flowering and fruiting

Grey mould, caused by Botrytis cinerea, is one of the most important diseases of raspberry. In the UK, the majority of raspberry production has recently switched to cropping under polythene tunnels but without corresponding changes in managing grey mould despite the fact that the risk of grey mould is greatly reduced under protection. On average, two to four applications of fungicides are specifically targeted at B. cinerea during flowering and fruiting, leading to more than 50% fruit containing detectable amount of fungicide residues. Based on new findings on epidemiology of this disease under protection, we have developed a new integrated pest and disease management strategy to manage grey mould where fungicides are not applied during the flowering and fruiting period, but rapid post-harvest cooling and cold storage is used to delay the onset of fungal rotting. This new strategy was evaluated over 2 years at two commercial sites. Our main findings are: (1) The strategy produced a marketable yield as high as the conventional programme and resulted in comparable levels of grey mould and (2) rapid post-harvest cooling and subsequent storage at 4–5°C or below generally led to a reduced level of fungal rotting of fruit 9 days after harvest, which is comparable to the average maximum post-harvest period before consumption. Thus, we concluded that this new strategy can be adopted for managing grey mould on raspberry grown under protection. Adoption of this strategy will not only reduce the fungicide input but also lead to production of fruit with zero fungicide residues.