ABSTRACT
Low crop productivity due to losses caused by the pathogens is a serious problem and has far-reaching implications on human population. Irish famine due to the late blight of potato (1845-1847) is a notorious example. According to a report, yield losses due to pathogens are estimated at 14% of the total agricultural production (Oerke et al., 1994). There are additional costs in the form of pesticides applied for pest control, currently valued at US$ 10 billion per annum. The losses made by insects, pests, diseases and weeds are estimated upto US$ 234 billion in eight major field crops (42%), out of total attainable production of US$ 568.7 billion worldwide (Sharma et al., 2001).
