Citrus Sudden Death (CSD) affects sweet oranges (Citrus sinensis) and some mandarins (Citrus reticulata) grafted on Rangpur lime (Citrus limonia) in the northern region of the State of São Paulo and south of the Triângulo Mineiro, Brazil. The progress of the disease in these groves is of great concern to citrus agribusiness. To characterize and quantify the damage caused by CSD, fruit yield (total weight and fruit number by plant, and fruit size) was assessed in four blocks for each combination of sweet orange varieties ('Hamlin', 'Pêra', 'Natal', and 'Valência') and class of age (three to five years, six to ten years, and 11 to 15 years). In each block, trees were classified according to CSD severity (0 = healthy, 1 = initial symptoms, and 2 = severe symptoms). For each severity level, ten trees were selected at random and harvested. Damage was characterized by reduction of total weight of harvested fruit per plant (28% and 50% for level 1 and 2, respectively), total number of fruit per plant (12% and 26% for level 1 and 2, respectively), and fruit size (22% and 41% for level 1 and 2, respectively). There was no difference in percentage of reduction of all evaluated variables of fruit yield among the tested sweet orange varieties. The youngest plants showed a higher reduction in fruit number per plant, while plants older than five years showed a higher reduction in fruit size. There was no difference in percentage of reduction of total weight of fruit per plant among plants of different age classes.
epidemiology; damage evaluation; disease severity; etiology; Citrus sinensis; sweet orange
