A significant phytosanitary alert has been issued in Spain’s key potato-growing region of Castile and León due to the widespread presence of Phytophthora infestans, the pathogen responsible for late blight (commonly referred to as mildew). The alert, communicated by the Junta de Castilla y León’s regional government, affects potato plots in multiple provinces, with urgent recommendations for growers to intensify control measures.

According to the region’s latest phytosanitary bulletin, recent weather conditions—characterized by high humidity and warm temperatures—have created ideal conditions for the proliferation of late blight, particularly in areas where crops are in full vegetative growth and canopy closure has already occurred.

The alert covers a wide geographic area, including the provinces of León, Valladolid, Palencia, Burgos, Salamanca, and Zamora. In several zones, outbreaks have already been confirmed, prompting authorities to recommend immediate treatment with registered fungicides and to closely monitor fields for new infections.

The bulletin stresses the importance of alternating active ingredients to avoid resistance and recommends shortening treatment intervals to ensure effective disease control. In areas where outbreaks have already occurred, applications should include curative products with systemic or translaminar action, in combination with protective agents.

The Junta also warns producers to follow good agricultural practices, such as avoiding irrigation during the night and early morning hours when humidity levels are higher, as well as removing infected plants and volunteer potatoes that can serve as disease reservoirs.

Late blight remains one of the most economically damaging diseases in potato production across Europe. The current alert is a stark reminder of the ongoing vulnerability of the sector to rapidly evolving phytopathological threats, especially in the context of climate variability.

The region of Castile and León represents one of Spain’s most important potato cultivation areas, making this outbreak particularly critical to both local and national production volumes.