Archivio Journal of Plant Pathology

Abstract:

Walnut blight, caused by Xanthomonas arboricola pv. juglandis (Xaj), is the most important disease of English walnuts (Juglans regia L.). Infections occur also on other Juglans species and inter-specific hybrids. With the aim of reporting the outputs of the Working Group ‘Genetic Resources’ of COST Action 873 on Xaj resistance/ tolerance of English walnut, the results of trials produced by this and other groups are illustrated and discussed in this paper. Methods of infection, descriptions of Xaj damages in leaves, and results of open field and laboratory tests are reported. The content of phenolic compounds of leaves and green fruits, and its relationship with tolerance/susceptibility, as well with host protection mechanisms against Xaj infection, are commented. Results show that a final and simple way for obtaining J. regia materials resistant to Xaj is not available. However, it looks like possible to find genotypes tolerant to Xaj out of native J. regia population where air temperature and humidity conditions favour the spreading of this bacterium.