For the first time, scientists have identified the existence in Álava-Araba of the two sexual types A1 and A2 of the fungus Phytophthora infestans, responsible for potato blight. Plant lesions become visible on day five following an attack by the fungus. The symptoms can be seen firstly on the lower leaves where a light-green or yellow spot can be seen on the tips and edges of the leaves. This spot separates healthy tissue from dead tissue. The lesions then spread across the remaining surface of the leaf and can be seen in the form of dark green, grey-brown or black patches.