EMERGING BACTERIAL AND PHYTOPLASMA DISEASES OF FRUIT TREES THAT ARE OR MAY BECOME A THREAT FOR THE MEDITERRANEAN BASIN: NOTES ON EPIDEMIOLOGY, RISKS, PREVENTION AND MANAGEMENT ON FIRST OCCURRENCE

Abstract

In this contribution the epidemiology, management and main risks of three emerging bacterial diseases of Citrus approaching the Mediterranean basin, their causal organisms and vectors will be highlighted: 1) Citrus huanglongbing or Citrus greening, caused by the heat tolerant “Candidatus” Liberibacter asiaticus and heat sensitive “Candidatus” L. africanus; both forms and their respective psyllid vectors Diaphorina citri and Trioza erytreae are present in the Arabian peninsula, while huanglongbing has been recently reported in Iran, Mali, Ethiopia and Somalia and T. erytreae in some Atlantic Ocean Islands; 2) leaf scorch and leaf scald diseases of grape and diverse fruit and ornamental trees, caused by Xylella fastidiosa, of which local possible vectors such as Cicadella viridis and Philaenus spumarius occur in Europe or the Mediterranean basin; 3) citrus canker, caused by Xanthomonas citri pv. citri, the most severe form, the so-called Asiatic, is present in Irak, Iran, Oman, Somalia, UAE, Saudi-Arabia, Yemen and Reunion. Information on outbreaks and possible emerging character of some other bacterial pathogens (Xanthomonas citri pv. mangiferaeindicae on mango, approaching like X. c. pv. citri the Mediterranean basin, and Phytoplasma phoenicium on almond destroying thousands of trees in Lebanon) will be also reported. It will be argued that the three first diseases mentioned are emerging threats, with real risks of introduction and in some cases closely approaching the Mediterranean basin.