EVALUATION OF SUSCEPTIBILITY OF 'PERA' SWEET ORANGE GENOTYPES TO CITRUS CANKER UNDER FIELD AND GREENHOUSE CONDITIONS
The use of resistant genotypes is the best way to control citrus canker, caused by the plant pathogenic bacterium Xanthomonas citri susbp. citri. Genotypes can be screened for resistance to the pathogen and germplasm found to have adequate resistance can either be incorporated into breeding programs or used directly for commercial plantings. Indeed, several genotypes of economic importance developed in Paraná State, Brazil, have been found to have satisfactory tolerance to citrus canker. The objective of this research was to evaluate sweet orange Pêra genotypes for their susceptibility to citrus canker. A total of 25 Pêra genotypes were evaluated in two orchards test in greenhouse inoculation studies. Disease incidence and severity in the field was estimated by assessing citrus canker on 10 plants per genotype. Four branches were sampled per plant on which the number of healthy and diseased leaves were counted, and the lesion numbers and the average severity (percent leaf area) were estimated for each diseased leaf. Estimates of severity were made using standard area diagram sets as an assessment aid. In the greenhouse, plants were grown in containers, and leaves of each genotype were inoculated by piercing the leaf with a needle and immersing the injured leaf in a suspenasion of X. citri subsp. citri inoculum (108 CFU/ml). Resulting lesion diameter was measured using a micrometer. The cultivar Pêra EEL showed the lowest disease incidence both under field and greenhouse conditions.
Aline M.O. Gonçalves-Zuliani, , William M.C. Nunes, , Carlos A. Zanutto, , José Croce Filho, and Paula T.R. Nocchi, (2015). EVALUATION OF SUSCEPTIBILITY OF 'PERA' SWEET ORANGE GENOTYPES TO CITRUS CANKER UNDER FIELD AND GREENHOUSE CONDITIONS. Acta Hortic. 1065, 511-516
Xanthomonas citri subsp. citri, incidence, severity, citrus, germplasm, diagrammatic scale, diameter of lesion