Rain forecasts raise disease risk for Spanish vineyards

Meteorological forecasts for the coming days predict significant rainfall in Spain's wine regions. The rain will hydrate the grapes, helping maintain their abundance and quality, but experts warn it could also increase the incidence of fungal diseases.

The Estación Fitopatológica de Areeiro reported that the overall sanitary condition of the vines remains good, yet isolated parcels show early signs of downy mildew and new leaf spots. Technicians highlighted the risk that high spore loads and moisture could exacerbate botrytis infections, especially on sensitive grape varieties with thin skins. They also noted the presence of adult Scaphoideus titanus, the vector of flavescence dorée, and advised continued cultural practices such as leaf removal to improve airflow and reduce the need for treatments.

A separate viticulture guide explained that the three main fungal threats—botrytis, downy mildew and powdery mildew—behave differently under wet conditions. While powdery mildew can develop without rain, downy mildew thrives on prolonged humidity, and botrytis becomes more aggressive when rain causes grape skin rupture. Managing canopy density and monitoring insect vectors are essential to protect grape quality and ensure a successful harvest.