A marked variation in tree size and bark scaling was observed on Navelina ISA 315 sweet orange infected by different viroids and grafted on Rubidoux trifoliate orange, Swingle CPB 4473 citrumelo, Carrizo CES 2863 and BA-300 citranges and Thomasville citrangequat rootstocks. Two-year-old rootstock seedlings were inoculated with a complex of three citrus viroids (CVds) and 6 mo later grafted with Navelina ISA 315 sweet orange. The trees were planted in 1994 and yield, fruit quality and size were

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... valuated every year. Bark scaling and gumming symptoms were also assessed on each rootstock. Each scion/rootstock combination inoculated with CVds showed a smaller tree size compared to the non-inoculated controls. The smallest canopy volume was observed in plants grafted on Rubidoux trifoliate orange and BA-300 citrange. Typical viroid symptoms (bark scaling, dieback and canopy yellowing) were observed on Rubidoux trifoliate orange, whereas BA-300 citrange and other rootstocks did not show any symptoms 10 yr after inoculation.