CHANGES IN SUSCEPTIBILITY TO BROWN-ROT WITH RIPENING IN 3 CLINGSTONE PEACH GENOTYPES

Susceptibility to.brown rot, caused by Monilinia fructicola (Wint.) Honey, changed with fruit ripening in the susceptible clingstone peach [Prunus persica (L.) Batsch] cultivar Corona and two moderately resistant genotypes. Nonwounded fruit were more resistant before epidermis color break from green to yellow. Susceptibility increased from color break to the period when the epidermis had acquired a uniformly yellow ground color. With continued ripening, susceptibility remained constant or decreased, depending on genotype. A ripeness index based on fruit color permitted objective within and between genotype comparisons of susceptibility. The genetic selection for precociously developing high yellow-orange flesh color has resulted in a clingstone peach selection possessing a flesh quality suitable for processing and with high levels of brown-rot resistance at the mature-green fruit development stage.