• Following its initial detection in Israel in January 2022, the presence of Diaphorina citri in Cyprus, which is EU territory, has now been confirmed. This should compel Brussels to investigate the origin of the outbreak and fund and oversee eradication measures.
• The Asian citrus psyllid is more concerning than the African Trioza erytreae, already present on the peninsula, because it is harder to detect, better adapted to our climate, breeds over a wider temperature range, and thrives more readily on Carrizo rootstock, which is predominant in Spain. Moreover, it transmits the most lethal strain of the most aggressive bacterium associated with Greening.
• If this vector were to arrive and coexist with T. erytreae, HLB, which has already devastated citrus farming in Florida and Brazil, could be detected in Spain in a short time. Consequently, Intercitrus demands immediate reinforcement of research in biological control, tolerant or resistant rootstocks and varieties, as well as field and border controls. It also calls for consideration of expanding these measures to include plant material carried by passengers.

The Mediterranean and the EU remain the only major citrus-producing region resisting the presence of the most devastating citrus disease the Huanglongbing or HLB (also known as Greening or ‘Yellow Dragon’), caused by the Candidatus liberibacter bacterium. However, this situation is now doubly threatened. On one hand, by the known expansion in northern Spain and along almost the entire Atlantic coast of Portugal of Trioza erytreae – the insect vector of the ‘more benign’ African strain of HLB – and now by the presence, for the first time in EU territory, of Diaphorina citri, which is the most efficient carrier of the most aggressive and lethal strain for citrus. This has just been confirmed in the latest report by the European and Mediterranean Plant Protection Organization (EPPO), which indicates that the insect has been located in Cyprus and confirmed by the European reference laboratory, specifically in the municipality of Asomatos (Limassol district).A finding that adds to the detection of this same vector, confirmed in January 2022, in Israel, which confirms its ability to spread in the Mediterranean. As it is an insect regulated as a quarantine pest, carrying a disease whose prevention, control, and detection are categorized as ‘priority’ – HLB – eradication measures to be adopted in Cyprus must be immediate. In this regard, Intercitrus urges the European Commission (EC) to open an investigation into the origin of the outbreak (not detailed by EPPO), supervise, and financially collaborate in the implementation of these actions to ensure their compliance and given the severity of what has occurred.

“The presence in our country of one or, worse, the increasingly greater risk of having both carriers of HLB, makes us think that the arrival of the most feared bacteria, against which there is no cure and which has been able to practically reduce citrus cultivation in Florida and significantly diminish it in Brazil, could be only a matter of time,” says the president of Intercitrus, Inmaculada Sanfeliu. For this reason, the interprofessional association calls on the authorities of citrus-producing regions, the Government, and the EC to immediately contribute to strengthening prevention measures and ongoing research lines for biological control against these vectors – for which there are no authorized effective insecticides in the EU – for obtaining rootstocks or varieties resistant or tolerant to the disease, as well as field controls for early detection and those established at borders to prevent their entry. Furthermore, the interprofessional association even calls on the EC, given the global benefit to plant health of European horticultural production, to consider the possibility of following the example of other Western powers – such as the United States, Australia.

 Diaphorina citri is the vector that most effectively contributes to spreading the Asian variant of the Candidatus Liberibacter bacterium, the most destructive: once infected, trees inevitably die within a maximum period of eight years, depending on the age and conditions of the crop. It can also transmit ‘Candidatus Liberibacter africanus’ and ‘Candidatus Liberibacter americanus’, and in areas where these three bacteria coexist, it can transmit them indiscriminately. Unlike the African psyllid (T. erytreae), which causes direct damage to trees (the nymphs feed on the sap of rutaceous plants and cause striking deformations in the leaves), D. citri by itself is not a harmful pest, but this makes it more ‘sneaky’, more difficult to detect. In addition, a study by the Valencian Institute of Agricultural Research (IVIA) – Jaume I University and the University of Florida has shown that the rootstock on which the vast majority of orange and mandarin trees in Spain are based – Citrange carrizo – “is an extremely favourable host for the development and reproduction” of this psyllid.

Indeed, the vector native to Asia is responsible for the spread of the disease in two of the world’s major and most advanced producing regions: Brazil and the United States. The strategy followed in the former case, based on constant renewal, removal of infected trees when not abandoned, and expansion to new plantations, but above all, on ‘bombarding’ farms with phytosanitary treatments against the psyllid, had relative success for decades and allowed the Brazilian industry to consolidate as the world’s leading exporter of orange juice, but the formula seems to have worn out. Today, after six consecutive years of increasing incidence, the disease in the entire citrus belt of São Paulo and Southwest Minas is present in 38% of the trees, and the reason for this evolution lies in the uncontrolled population of D. citri, which has become resistant to the most effective insecticides used so far. In Florida, on the other hand, the presence of HLB was confirmed in 2005, but the disease must have settled years earlier: in the 1997/98 season, it reached its production record with 12.3 million tons (Tm); currently, this figure has been reduced to 740,534 Tm, the lowest since 1930.

“Spain, in the event that HLB arrives, would hardly be able to contain the disease, and it is almost certain that the bacterium would ultimately destroy our sector,” warns Sanfeliu. Extrapolating the figures from the evolution experienced in Florida, in 7.5 years from its possible entry, the production of oranges, mandarins, and lemons would be halved (from 7 million Tm to 3.6 million), and after 15 years, citrus cultivation would become a residual crop. The fragmented structure and stricter European regulations on environmental and phytosanitary matters – which prohibit the pyrethroids and neonicotinoids used against D. citri – would leave less room for Spain’s reaction than Brazil or Florida have had. “We must buy time to find solutions to combat the disease,” concludes the president of Intercitrus.