Relative susceptibility of citrus genotypes to fruit rot caused by Ceratocystis radicicola in Iran

Abstract

Several citrus genotypes were evaluated for their relative susceptibility to the new lemon fruit rot pathogen, Ceratocystis radicicola. Wounded detached fruits were inoculated ten days before normal harvest by placing on the wound site a droplet of distilled water followed by a mycelial plug of one-week-old culture. Inoculated fruits were ranked for their relative susceptibility to the pathogen by determining disease severity based on mean lesion size. Using Duncan ' s multiple range test, citrus varieties were classified into three groups, as follows: most susceptible: Mandarin (cv. Clementine); moderately susceptible: Mandarin (cvs. Dancy, Ponkan, sweet lime and common sour orange) and least susceptible: Mandarin (cvs. Kinnow, Lee, Fortune and Osceola), grapefruit (cvs. Marsh and Red Blush), orange (cvs. Parson Brown, Marss Early, Salustiana, Washington Navel and Hamlin) and lemon (cv. Lisbon). Alternatively, fruit firmness was measured using a hand-held penetrometer at the time of inoculation. Disease severity was negatively correlated (R = -0.36, P < 0.01) penetrometer at the time of inoculation. Disease severity was negatively correlated (R = -0.36, P < 0.01) at the time of inoculation. Disease severity was negatively correlated (R = -0.36, P < 0.01) with fruit firmness. Although this study aimed to determine the range of potential hosts for C. radicicola, to date the only natural host in the world is considered to be lemon.