Evaluation of resistance of ‘Pera’ (Citrus sinensis) genotypes to Citrus Canker in field and greenho

The use of resistant genotypes is an important alternative in the control of Citrus Canker caused to Xanthomonascitri. The objective of this study was to evaluate genotypes of the ‘Pera’ sweet orange for resistance toCitrus Canker in the field and under greenhouse conditions. A total of 25 genotypes of ‘Pera’ sweet orangewere evaluated in orchards and in a greenhouse in the state of Parana, Brazil. To determine the incidenceand severity of disease in the field 10 plants were evaluated per genotype, with samples consisting of fourbranches per plant. Data collected included counts of the total number of leaves, the number of diseasedleaves, number of lesions and an inferred average of severity using a diagrammatic scale. In greenhousetreatment, leaves were inoculated by piercing with a needle (0.55 x 0.20 mm), containing X. citri inoculumadjusted to 108 CFU / ml at 600 nm and evaluated with the aid of a micrometer. The results were submittedto ANOVA and means were compared by Scott Knott test at 5% probability. In field conditions ‘Pera EEL’, ‘PeraCoroada’ and ‘Pera Ovale Siracusa’ genotypes showed no symptoms of disease in the three regions evaluated. In the greenhouse test, ‘Pera EEL’ (1.74 mm) and ‘IAC 2000/1’ (1.73 mm) genotypes showed smaller diameterslesions. An increase in diameter of the lesions was observed over time, requiring 61 days after inoculation(DAI) for the lesion size to be stabilized.