Other materials

The partner of Tropicsafe CIRAD has published a research article under teh title "Specific Physiological and Anatomical Traits Associated With Polyploidy and Better Detoxification Processes Contribute to Improved Huanglongbing Tolerance of the Persian Lime Compared With the Mexican Lime".

Cécile Morillon and TROPICSAFE Guadelaoupe partners, CIRAD, designed this entertaining comic about Huanglongbing (HLB), the Citrus Disease. HLB is one of bacterial diseases threatening selected tropical and subtropical areas and is one of the study object in the project. The comic tells the story of the "Dragon Yellow Disease", the insects vectors and the interesting process followed in the TROPICSAFE project to give solution to this problem.

Citrus production has been widely affected by pathogens which causes economic losses to the growers resulting in severe social effects in many of the areas where the economy is based on agriculture. In the past decade citrusassociated phytoplasmas have originated widespread epidemics in some citrus-growing regions of the world. They are associated to either specific symptoms such as witches’ broom or non-specific symptoms like leaf yellowing, leaf mottling and lopsided fruit. So far about 21 citrus cultivars have been reported to be infected by phytoplasmas enclosed in 11 ribosomal groups; among these 16SrI (aster yellows) and 16SrII (peanut witches’ broom) are the most widespread. Here symptomatology, economic importance, transmission and strategies used for disease management are reported together with the molecular classification of the detected phytoplasma strains in Asian, American and African continents.

The confirmation of the presence of 16SrXXII-B phytoplasmas associated with coconut lethal yellowing disease in Ghana and of 16SrIV in the Caribbean (Jamaica, Cuba, and Mexico) were the basis to study alternative plant species and potential insect vectors of this economically relevant disease carried out by the TROPICSAFE project started in 2017. In South Africa grapevine yellows disease associated with ‘Candidatus Phytoplasma asteris’, (subgroup 16SrI-B) and transmitted by the leafhopper Mgenia fuscovaria was studied in its main epidemiological aspects that are relevant to its management. In Chile and in Italy phytoplasmas belonging to diverse ribosomal subgroups and several alternative host plants were detected. Some insect species have been described as phytoplasma vectors or potential vectors in grapevine or in vineyard environments.

Maritza Luis Pantoja and Camilo Paredes Tomás from the Research Institute of Tropical Fruit Crops (IIFT) explain the evolution of the Cuban citriculture from the beginning of the citrus program in 1968, highlighting the impact of HLB in the production. The authors describe the most frequently observed symptoms, the pathogens detected, and the control measures used to reduce the incidence of the Diaphorina citri vector in the orchards.

Nicola Fiore from the Faculty of Agricultural Sciences of the University of Chile Santiago presents an overview of the GY disease in Chile, where its presence in V. vinifera was first reported in 1971. The symptoms observed, the most widespread phytoplasmas and the insect vectors that can transmit the disease are explained in this article

In Jamaica, coconut palms are an important source of income and a vital part of the subsistence agriculture in rural villages. This article explains how the spread of Lethal Yellowing through the coconut growing areas is impacting in many vulnerable communities, by threatening income as well as food security. The authors, Sonia Marongiu from the Council for Agricultural Research and Economics (CREA) Italy and Wayne Myrie from the Coconut Industry Board (CIB) Jamaica, explain the evolution of the disease in this country.

The text explains the associations between phytoplasmas and the most widespread diseases in coconut palms in the Americas, the Caribbean region and Africa. Assunta Bertaccini from UNIBO, Tropicsafe coordinator and author of the article, introduces the economic impact of LY that is killing millions of palm plants in the main coconut producing areas.

The article describes HLB, a devastating disease affecting citrus. Authors, Alejandro Tena and Jessica Pérez-Rodríguez from IVIA , explain the impact on the production and how the affected countries are managing it. Some symptoms of the diseases are also explained. Insect vectors (Diaphorina citri in Asia and America, Trioza erytreae in Africa and very recently also in Europe) are presented, as well as some guidelines to identify them. Finally, a short preview of Tropicsafe activity to improve the biological control of T. erytreae in Europe is included.

The article by Assunta Bertaccini, from the University of Bologna, studies the different insect-borne prokaryote-associated disseases in partner countries. The presence of phytoplasmas associated with coconut lethal yellowing disease in Ghana and in the Caribbean were the basis to study alternative plant species and potential insect vectors of this economically relevant disease. In South Africa grapevine yellows disease associated transmitted by leafhoppers was studied in its main epidemiological aspects that are relevant to its management. In Chile and in Italy phytoplasmas belonging to diverse ribosomal subgroups and several alternative host plants were detected.

A table reporting phytoplasmas associated with the main GY in the world is presented in this article, which also describes differences among epidemiological cycles of GY in the different geographical areas, due to phytoplasma and insect vector diversity. Assunta Bertaccini from UNIBO and Elisa Angelini from CREA introduce the work planned under Tropicsafe framework to tackle the lack of information about grapevine susceptibility to GY, its vectors, their seasonal trend, and management strategies.

Citrus producers and associations from Guadeloupe are talking about the impact of HLB in their plots and production systems. “Several producers have lost all their plots and are having big financial difficulties” says Uneau Youri, Tropicsafe partner representing ASSOFWI, an association that aims to develop fruit diversification in Guadeloupe.