AbstractThe chironja (clone 2-4) was evaluated during eight years of growth at Isabela and Corozal, Puerto Rico, in the coastal and central areas, respectively. The trees were grafted on the roostocks 'Swingle citrumelo' (Citrus paradise), 'Naronja' (Citrus paradisi x Citrus aurantium), 'Cleopatra', and 'Sun Chu Sha' mandarins (Citrus reticulata), and on the hybrid HRS 812 (Sunki mandarin x Beneck trifoliate orange). The trees of the Swingle-chironja combination died at both localities during the first year because of scion-rootstock incompatibility. The rootstock HRS 812 was one of the highest yielders, even though it was infected with severe strains of the Citrus Tristeza Virus (CTV) at both sites. Although the fruits on this rootstock were small, the amount of juice was significantly greater than that of the other rootstocks at both localities. Eight years after planting, the Naronja trees were affected by CTV; 38% of the trees were lost at Isabela, and 25% at Corozal. Nevertheless, trees on this rootstock were vigorous and good yielders, producing fruits of good size and moderate fruit quality. The high incidence of CTV and Phytophthora spp. was a limiting factor for the rootstocks susceptible to these diseases; thus there was a high mortality.
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