ABSTRACT
Late blight (Phytophthora infestans [Mont. ] de Bary) is the most devastating disease of potato worldwide. CAB International (Anonymous, 2003) currently lists 122 countries where late blight has been reported, but it certainly occurs in more countries for which no report has been made. The economic and social impact of this disease was best experienced during the Irish famine in the 1840s when millions of Irish people either died or emigrated (Bourke, 1993) due to starvation caused by killing of the potato crop by P. infestans. At present, about $77 million are spent only on fungicides per season throughout the United States for control of this disease (Guenther et al., 2001). Yearly fungicide usage for late blight control in Europe is estimated to be about $150 million (H. Schepers, personal communication). The International Potato Center (CIP) estimated fungicide use in developing countries at $750 million (Anonymous, 1997). Based on these estimates, about $1 billion per year is spent on the fungicides to control late blight in the United States, Europe, and developing countries. These huge social and economic consequences of late blight have attracted considerable attention from research workers. This chapter reviews the current state of knowledge and advances made in understanding and controlling this most dreaded malady of potatoes.
