The use of aerobiological methods for forecasting Botrytis spore concentrations in a vineyard

Grey mould, caused by Botrytis cinerea, is one of the most common diseases in Galician vineyards. Knowledge of local airborne spore concentrations is of great value for developing models to predict fungal propagule concentrations, thus enabling phytosanitary treatments to be applied when a real risk of infection is detected. In order to develop an accurate model for forecasting airborne B. cinerea spore concentrations, a phenological and aerobiological survey was carried out in a vineyard located in Galicia (north-west Spain), from 2004 to 2008. Phenological observations were made on 20 vines of each of three grape varieties (Treixadura, Godello and Loureira) using the BBCH standardised phenological scale. A Hirst-type volumetric spore-trap was used for the aerobiological monitoring. The study sought to chart Botrytis spore concentrations as function of grapevine phenological stage. The highest spore concentrations over the grapevine cycle as a whole were recorded in 2008 (37299 spores), and the lowest in 2005 (1700 spores). In the five study years, the highest concentrations were registered during stage 8 (berry ripening), stage 7 (fruit development) and stage 5 (inflorescence emergence). The weather-related parameters displaying the most significant correlation with spore concentrations were dew point and relative humidity. ARIMA (Autoregressive Integrated Model of Running Mean) time-series models was used to forecast daily spore concentrations, considering B. cinerea spore concentrations and weather data as predictor variables.