Xianming Chen
USDA-ARS and Department of Plant Pathology, Washington State University, USA

Crop diseases caused by a great variety of microbes can result in huge economic losses. Control of most crop diseases primarily relies on resistance plants have acquired mostly during the long term co-evolution of the plants and pathogens. However, pathogens have also developed various arsenals to overcome plant resistance during the co-evolution; and particularly a pathogen can develop new pathotypes which can circumvent the resistance genes in varieties developed through breeding and widely grown for production. For every disease, environmental conditions influence greatly the plant-pathogen interactions and the results of epidemics. Various types of resistance exist in plant populations and each type has advantages and disadvantages.  Better strategies of utilization of the different types of resistance may achieve adequate and durable resistance under different environments. Breeding cultivars resistant to diseases in the past century has tremendously increased production of agricultural crops, but also has met great challenges. The advances in functional genomics of crops and pathogens, mechanisms of plant resistance and pathogen virulence, disease epidemiology, and biotechnology have made possible for more efficient development of high-level and durable resistance through utilization of genes in crops, from related species, and even from pathogens.  In a long run, sustainable production of an agricultural crop can be achieved by utilizing plant resistance in more effective approaches which can minimize the direct selection of more dangerous plant pathogens or pathotypes.