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PRE-HLB: Prevention of the spread of HLB in citrus cultivation

PRE-HLB is a project funded by the Horizon2020 Framework Programme whose objective is to prevent the entry of Huanglongbing disease (HLB) into Europe and, if it occurs, to prepare the necessary mechanisms for its effective control in the short, medium and long term. The PRE-HLB project, launched in Faro on 23 and 24 July 2019 with the assistance of all consortium members, has a grant of 8,001,690 euros and will be developed over the next four years.

The Institute of Molecular and Cellular Plant Biology (IBMCP), a joint centre of the Consejo Superior de Investigaciones Científicas (CSIC) and the Universitat Politècnica de València, are coordinating this European project, with the collaboration of 24 other partners from nine countries in Europe, America and Asia in which ZABALA Innovation Consulting participates.

About Pre-HLB

IBMCP researcher Leandro Peña, who leads the project, explains that “HLB is considered the most devastating of citrus diseases. This is due to its rapid dispersion, the aggressiveness of its symptoms, the high economic losses it causes, the difficulty of preventing new infections and the absence of lasting control mechanisms. HLB affects all varieties and rootstock of citrus, but to date no resistant genotype has been found”.

Huanglongbing disease, native to Southeast Asia, has spread in just over a decade to almost every citrus-growing region of the world. China, Florida (USA) and Brazil, the world’s largest citrus producers, are affected by HLB and suffer significant economic losses. HLB is caused by three species of bacteria of the genus Candidatus Liberibacter, transmitted by the insects Trioza erytreae and Diaphorina citri. Both insects have been detected in the Azores, in the Canary Islands and the Trioza erytreae in the Iberian Peninsula.  Although the bacteria causing HLB have not yet been detected in the European Union, the risk of entry is high, due to the enormous circulation of goods and people, as well as the illegal imports of plant material from citrus and ornamental citrus relatives.

“Experience in other regions indicates that once an insect dispersing the HLB is present, as soon as the causative bacterium enters, the spread of the disease is unstoppable. It is therefore urgent to take the necessary measures to prevent the introduction of HLB in Europe and, if it does occur, to detect and eradicate it quickly” adds Leandro Peña.

The first measures proposed in the Pre-HLB project are informative, to raise awareness of the existence of HLB and its aggressiveness, as well as to train citrus growers in the identification of symptoms. At the same time, attempts will be made to prevent the arrival of the bacteria by identifying and inspecting the critical entry points, and the presence and dispersion of vectors will be monitored. In a second stage, Trioza erytreae dispersion models will be established in different areas of the EU to predict its movement, as well as farm management models to fight against HLB. New insect control tools and early diagnosis techniques will be developed.

“We hope to limit the spread of HLB if the initial phase of the epidemic occurs. In the long term, Pre-HLB intends to implement new sustainable strategies to limit the impact of HLB, such as the use of new biopesticides and antimicrobial products or varieties and rootstocks that are resistant to the disease. It is also a milestone for citrus growing because it is the first citrus initiative in which Europe, the Americas and Asia are collaborating. An essential aspect of this collaboration is that, in addition to having partners with extensive experience in the management of the disease, it offers the possibility of testing developments generated in Europe in countries where HLB is already present,” concludes Leandro Peña.

Characteristics of the HLB

Symptoms characteristic of the infection. (A) In the early stages of the disease, symptomatic trees are characterized by one or more yellow shoots that stand out over the green crown of the tree. (B) Defoliated tree infected by HLB. (C) Asymmetric chlorosis in leaves, characteristic symptom of HLB infection. (D) Orange coloration in the vascular bundles of the stalk end, while in healthy fruits the coloration is pale green (E). (F) Reversal of color of fruits when ripe. (G) Deformation and necrosis of vascular bundles. (H) Presence of aborted seeds in citrus fruits affected by HLB. Photographs provided by Fundecitrus (Fundo de Defensa da Citricultura).


Pre-HLB is formed by a multidisciplinary consortium led by IBMCP (CSIC-UPV, Spain). The other partners are: Institute of Agrochemistry and Food Technology –IATA, CSIC (Spain), Institute of Agricultura Sciences –ICA, CSIC (Spain), Instituto Politecnico de Braganca –IPB (Portugal), Consiglio per la Ricerca in Agricoltura e l’Analisi Dell’Economia Agraria –CREA (Italia), Consiglio Nazionale Delle Ricerche – CNR (Italia), Centre De Cooperation Internationale En Recherche Agronomique Pour Ledeveloppement –CIRAD (Francia), Instituto Valenciano De Investigaciones Agrarias– IVIA (España), Empresa Brasileira De Pesquisa Agropecuaria Embrapa– EMBRAPA (Brazil), The Chancellor Masters And Scholars Of The University Of Cambridge – UCAM (Reino Unido), Universiteit Van Amsterdam – UVA (Países Bajos), University Of Durham – U DURHAM (Reino Unido), Hunan Agricultural University – Hunan Univ (China), Anti Microbial Peptide BiotechnologiesSl – Ampbiotech (España), Koppert Espana Sl – Koppert España (España), Martinavarro Sl – Martinavarro (España), Conselleria De Agricultura, Medio Ambiente, Cambio Climático Y Desarrollo Rural – AGROAMBIENT (España), Fundo De Defesa Da Citricultura Fundecitus – FUNDECITRUS (Brazil), Asociacion Valenciana De Agricultores – AVA-ASAJA (España), Zabala Innovation Consulting, S.A. – ZABALA (España), Universita Degli Studi Di Catania – UNICT (Italia), Universitat Politècnica De València – UPV (España), Valgenetics Sociedad Limitada – ValGenetics (España), Universidade Do Algarve – UALG (Portugal), Frusoal – Frutas Sotavento Algarve Lda – Frusoal (Portugal), The Agricultural Research Organisation Of Israel – The Volcani Centre – VOLCANI CENTRE (Israel)