A problem case study: Influence of climatic trends on late blight epidemiology in potatoes

Late blight is temporally sporadic in potato crops in the Midwest US, occurring only when microclimate conditions within canopies are favorable and inoculum is present. Increasing concern over climate change projections has prompted numerous crop-based studies on the possible agricultural implications. It is not possible to evaluate sustainability without understanding the interactions between the influence of climatic trends, host resistance, cultural interventions and fungicide efficacy in relation to late blight risk. The objectives of this case study were to report the potential impact of climate change on late blight epidemiology in potatoes. Analysis of historical data from 1948-1999 indicated that late blight risk over a standardized growing season from 1 May-30 Sep increased in the Upper Great Lakes region of the US. Predominant genotypes of P. infestans (e.g. US8) in the US appear more tolerant of temperatures close to 0degreesC and their survival in warming conditions may explain their supremacy. As conditions become increasingly favorable for late blight development it is essential to reduce sources of initial inoculum through integrated approaches that include prediction of conditions conducive to late blight development and appropriate application of controls.