TROPICSAFE project: identification and management of phytoplasma-associated diseases in coconut palms in Ghana, Mexico, Jamaica and Cuba ed in grapevine in South Africa, Chile and Italy.

The TROPICSAFE project covers the diseases associated with phloem limited bacteria associated diseases in coconut palms, grapevine, and citrus species in diverse countries (http://www.tropicsafe.eu/). A part for the citrus “huanglongbing” disease associated with the presence of ‘Candidatus Liberibacter’ species mainly studied in Cuba, France (Guadeloupe), South Africa and Spain where for the moment only one of its insect vectors, Trioza eritreae is present, the project studies the epidemiology and management of coconut palms and grapevine associated phytoplasma diseases. Coconut palm lethal yellowing (LY) is studied in Ghana, Cuba, Jamaica and Mexico and grapevine yellows (GY) are studied in Italy, South Africa, and Chile. The presence and the identity of the pathogen strains present in the different countries was verified through their molecular characterization and in some cases also cultivation in artificial media to acquire the data necessary to detect and manage in sustainable manner the studied diseases. The pathogen identification in alternative host plants and insects vectors and potential vectors was also performed together with the improvement of specific diagnostic techniques. The confirmation of the presence of 16SrXXII-B and 16SrIV phytoplasmas in Ghana and in the Caribbean (Jamaica, Cuba, and Mexico), respectively, allowed to study alternative plant species and potential insect vectors to define the epidemiological cycles of this disease towards its focused management. In Jamaica where the LY disease has been managed since some time with sustainable results a newly discovered species Oecleus mackaspringii was associated with coconut palm in plots with still active cases of the disease acting as possible insect vector. In Cuba also symptomatic palms positive for phytoplasmas belonging to the ribosomal groups 16SrI, 16SrVII and 16SrXII were identified and citrus with “huanglongbing” symptoms the 16SrIV phytoplasma was found in mixed infection with ‘Ca. L. asiaticus’ or other phytoplasmas. In Mexico transmission trials with Haplaxius crudus confirmed its vector role in this Country. Dwarf coconut varieties showed promising results in relation to LY resistance in Ghana. GY disease are associated in South Africa with ‘Candidatus Phytoplasma asteris’-related strains transmitted by Mgenia fuscovaria, while Chile and in Italy phytoplasmas belonging to diverse ribosomal subgroups, several alternative host plants, and some insect species have been described as phytoplasma vectors or potential vectors in grapevine or in vineyard environments. In Chile the 16SrIII-J phytoplasma is transmitted by Paratanus exitiosus and Bergallia valdiviana. Surveys in selected north Italy vineyards detected ‘Ca. P. solani’, ‘Ca. P. fraxini’, ‘Ca. P. asteris’ and “flavescence dorée” phytoplasmas and new potential insect vectors. It is therefore clear that only a constant monitoring will allow for the prompt detection of phytoplasmas or new phytoplasmas that may infect the studied crops. Appropriate management is linked to the diverse geographical location and agro-ecosystem conditions but with the appropriated epidemiologic knowledge can be applied as sustainable tool to reduce economic losses and the environmental pollution.