Identification of Novel Physiological Races of Phytophthora capsici Causing Foliar Blight Using the New Mexico Recombinant Inbred Pepper Lines Set as a Host Differential

Phytophthora foliar blight caused by Phytophthora capsici is a serious limitation to pepper ( Capsicum annuum ) production worldwide. Knowledge of the physiological race composition of isolates causing phytophthora foliar blight is necessary for success in breeding for disease resistance. The New Mexico recombinant inbred lines (NMRILs) effectively differentiated isolates from different geographical locations (i.e., Turkey, The Netherlands, Argentina, and two states in the United States) into 12 physiological races of P. capsici causing phytophthora foliar blight. This research demonstrates the use of the NMRILs to identify P. capsici foliar blight races and the importance of identifying the physiological races occurring in specific regions where a C. annuum cultivar will be grown. Knowing the physiological race(s) in a region will provide valuable information to formulate breeding strategies to deploy durable foliar blight resistance.