Late blight caused by Phytophthora infestans (Mont.) de Bary. It has historically been an important disease of potatoes worldwide. In the mid-1800, it caused widespread crop failures throughout Northern Europe including Ireland and it is responsible for the Irish famine during 1845. It is one of the most dramatic episodes caused by plant pathogens in human history. The sporangia are usually produced between 8 and 26 ºC with an optimum of 19-22 oC of temperature. More sporangia are formed at low wind speeds when the ambient RH is 90-100 per cent. Modelling on late blight potato is an attempt to describe disease onset and progress using many factors that affect blight. Forecasting allows the prediction of probable outbreaks and helps in the decision support system for the management of late blight. Various concepts utilized and developed over the years for predicting late blight across the globe. They include ‘Dutch rules, Beaumont’s periods, the moving day's concept, Irish rules, severity value accumulation, negative prognosis, mathematical models etc. Control of the disease has been achieved up to a great extent through the use of fungicides, but their extensive application is harmful to the environment. Therefore, an urgent need to find eco-friendly alternative crop protection methods. The use of microorganisms owing to their different modes of action has proved to be a potential approach and providing genetic resistance against pests and diseases is another crop protection approach.