The disease of potato responsible for famous famine of Europe was caused by or late blight of potato is caused by 

(a) Colletotrichum falcatum 

(b) Phytophthora infestans 

(c) Potato mosiac virus 

(d) Alternaria solani 

Answer. (b) Late blight of potato is a seed born disease which is caused by Phytophthora infestans. The disease is characterised by brownish to blackish dead areas on the tip and margin of the leaflet leading to blighting of the whole leaf. So the tuber formation is reduced.