Innovation Factsheets

Description of the rapid 20 minutes in-field system for the 16SrXXII ‘Candidatus Phytoplasma palmicola’ detection in coconut in Africa that the project is developing to improve current efficient management options for the lethal-yellowing type diseases, such as rapid and systematic removal and burning of infected palms, followed by replanting with healthy palms.

One of the aims of TROPICSAFE is to evaluate the impact of the solutions proposed to manage lathel yellowing, one of the most serious diseases affecting coconut in the world. The focus is made on Jamaica, Ghana, and Mexico, where the spread of the disease in the last decades has been responsible for the loss of an overwhelming majority of coconut production.

Among the more serious phytoplasma disease are lethal yellowing of palms (Eziashi and Omamor, 2010). Nowadays there is a National Program to recover the Cuban coconut industry and in this frame it was very relevant to verify the identity of phytoplasmas associated with lethal yellowing to support the further development of strategies to more effectively monitor and manage the disease in the country.

Under the framework of TROPICSAFE, resistance to lethal yellowing disease and agronomic performance of the IBD, NLD, NGBD, SGD, and MGD coconut varieties are being evaluated. The aim is to identify the best option for fighting LY disease of coconut in Ghana.

Impact of management practices on the spread of the disease in Jamaica. Sustainable lethal yellowing management for the coconut industry in Jamaica.

Lethal yellowing is a great threat to the coconut value chain in many countries. The use of lethal yellowing resistant germplasm as a basis for disease management is tested by TROPICSAFE partners in Mexico, Cuba and Jamaica.

Coconut is a palm species cultivated worldwide. It is very important because several products can be obtained from it, particularly from the fruit. The markets of coconut products (pack water, virgin oil, and others) are currently growing very fast. Unfortunately, fruit production is slowing down, mainly because phytosanitary issues and old age of plantations.

TROPICSAFE is carrying out surveys and characterizations of ‘Candidatus Liberibacter’ lineages, associated with the citrus greening disease, one of the most important citrus pathogens. This work will provide improved knowledge of the potential alternate host plants and insect vectors that can be one of the means of spreading of the pathogen to parts of the world that are currently disease-free.

One aim of TROPICSAFE is the impact evaluation of the solutions proposed to manage citrus “huanglongbing” (HLB), detected in several areas of the world where it has caused big losses. The citrus market analysis is conducted in Cuba, Guadeloupe (France) and Spain.

Explanation of the results of the management strategy to reducte the impact of “huanglongbing” in Cuba. The main elements of this strategy are an infected-tree eradication; and the implementation of two practices for control of Diaphorina citri, the entomopathogenic fungus Hirsutella sp. and kaolin applications.

TROPICSAFE has initiated a classical biological control program to fight the “huanglongbing” disease and its presence in Europe, by the introduction of a natural enemy from its area of origin, the parasitoid Tamarixia dryi (South Africa).

The main threat to the citrus industry has no biological control agents in Europe. Recent studies carried out by TROPICSAFE and other research groups have demonstrated that the psyllid vector has no potential biological control agents that can control it in Europe.

The Asian psyllid vector of ‘Candidatus Liberibacter asiaticus’ was identified in Guadeloupe in 1998 (Etienne et al., 1998) and citrus ‘’huanglonging’’ disease was detected in 2012. As there is no curative solution, different sustainable plot management methods have been tested to propose cropping systems adapted to manage the producers’ constraints.

How to recognize different types of symptoms in infected trees, leaves, and fruits. Protocols for monitoring the vectors and detecting the disease are part of the TROPICSAFE project. It was found that very small quantities of psyllids are sufficient to infect orchards, with sometimes non-symptomatic trees that can die off very quickly.

Description of the identification of phytoplasmas associated with grapevine yellows diseases that are being carried out in the project. These detection activities are being developed in Chile, Italy, and South Africa with the aim of focusing the disease management efforts.

In Chile, grapevine yellows is associated with phytoplasmas belonging to diverse ribosomal subgroups. However, the phytoplasmas in the 16SrIII-J subgroup are prevalent in the vineyards of the country. This phytoplasma has been reported to infect various crops and spontaneous plant species.

Friendly detection methods for identification of selected phytoplasmas associated with grapevine yellows.

One of the aims of TROPICSAFE is to evaluate the impact of the solutions proposed to manage grapevine yellows, the phytoplasma-associated diseases considered one of the most important of the world grapevine sector. General framework in Chile, Italy and South Africa.

Problems and losses due to grapevine yellows diseases in the world. Identification of candidate genetic traits associated with resistance to grapevine yellows.

As grapevine yellows has been studied in the European areas for decades, the biology and epidemiology of the most frequently associated phytoplasmas are well studied, and their main reservoir plants and insect vectors have been identified. However, changing environments and the recent introduction of several alien species of both potential phytoplasma insect vectors and weeds has increased the risk of spread of new phytoplasmas or new strains that might affect the sanitary status of the vineyards.

Analysis of the activity being developed by TROPICSAFE to make available certified material that can be very useful for a fast and accurate detection of grapevine yellows phytoplasmas. The project is working on two types of reference materials for grapevine phytoplasmas, using ‘Candidatus Phytoplasma solani’ associated with “bois noir" as a model.

TROPICSAFE aims to develop new solutions to manage grapevine yellows based on improved knowledge of the biology of the associated phytoplasmas and insect vectors, epidemiology, development of reliable, cost-effective detection methods, and exploring crop resistance/tolerance.

The descriptions of severe epidemics of grapevine yellows in Italy date back to the 1990s, when severe losses mainly due to the presence of “flavescence dorée” were reported especially in the northern regions. In the following years in other regions the presence of “bois noir” and erratically of other phytoplasmas was also described. The economic impact of the grapevine yellows disease had been under control over the past 20 years, until recently scattered outbreaks and localized epidemics started to re-emerge.

Plants are inhabited by a wide diversity of both beneficial and harmful microorganisms such as fungi, bacteria and viruses. These microorganisms, the microbiome, closely interact in networks that can for instance be antagonistic or symbiotic. ‘Candidatus Phytoplasmas’ and ‘Ca. Liberibacter’ species are part of this network and compete with the remaining microbiome for nutrients and space interacting with other plant-associated microorganisms.