Fungal spores affecting vineyards in Montilla-Moriles Southern Spain

Abstract

The most common Vitis vinifera diseases are powdery mildew (Uncinula necator), grey mould (Botrytis cinerea) and downy mildew (Plasmopara viticola). Greater knowledge of the factors involved in fungus reproduction and plant infection will help to fine-tune treatment application calendars, thus cutting farmers’ costs and reducing adverse environmental effects. The main aim of this study was to investigate the relationship between airborne spore concentrations, weather-related parameters and grapevine phenology. Phenological observations and airborne spore detection were carried out during the Vitis vinifera growing period (February–August) from 2015 to 2017. Phenological data were collected weekly for four grape varieties (Pedro Ximenez, Verdejo, Muscat a petit grains and Chardonnay). Airborne fungal spores were monitored using one Hirst-type volumetric spore trap, following the standard protocol developed by the Spanish Aerobiology Network (REA) and the European Aeroallergen Society (EAS), and 4 Passive Spore Traps (PST), following the protocol proposed by Kelly et al. (Phytopathology, 105, 905–916, 2015). During this study, U. necator was the most common, followed by B. cinerea and P. viticola. A significant correlation was found between the all PSTs weekly spore concentrations and the Hirst sampler but the seasonal spore integral was always higher for the Hirst-type sampler than for PSTs. Airborne U. necator spore concentrations were higher prior to blooming, and correlated with average temperature and rainfall. B. cinerea recorded the highest concentrations during leaf development, inflorescence emergence and flowering; airborne spore concentrations were correlated with both dew point and daily average temperature. P. viticola presented lower concentration but it was most frequently recorded spore during the stages prior to blooming, and displayed stronger correlations with humidity, dew point and average temperature. Weather conditions over the study period in the Montilla-Moriles Protected Designation of Origin (PDO) area probably gave rise to spore concentrations lower than those reported for vineyards elsewhere in Spain, but higher than those recorded locally in areas where not associated with vineyards. The Hirst-type sampler yielded spore data representative of the whole study area. Knowledge of the factors influencing fungal spore concentration will help to fine-tune treatment calendars, and thus reduce the economic and environmental effects of treatment.