Characterization of the horizontal resistance of coffee (Coffea arabica) to yellow rust (Hemileia vastatrix) in the field and laboratory

Abstract

Between 2011–2013, yellow rust unleashed one of the most important phytosanitary crises in the coffee sector in Peru, causing a negative impact on the rural family economy. One of the factors associated with the intensification of the disease was the predominance of susceptible cultivars in agricultural systems. Faced with the need to rehabilitate the coffee park with new cultivars, the National Institute for Agrarian Innovation (INIA) has managed the installation of basic coffee germplasm for the development of the yellow rust resistance program, which is made up of 169 introductions from the departments of Pasco, Junín, Huánuco, Ucayali, Cajamarca, and Amazonas and obtained from 2015. The objective of the study was to evaluate the incidence and severity of epidemic conditions in the field and characterize the components of horizontal resistance, using the method of inoculations of H. vastatrix in separated coffee leaves in the laboratory. The epidemiological results collected from the field indicate that 12.43 and 20.71% of the genotypes showed complete and incomplete resistance, respectively; 66.86% showed high susceptibility to the pathogen. Three of the outstanding genotypes gave a typical horizontal resistance reaction when artificially inoculated with uredinospores on separated coffee leaves kept in a humid chamber.