In a significant development for the European citrus industry, the presence of Diaphorina citri, the notorious vector responsible for spreading the devastating Huanglongbing (HLB) disease, has been officially confirmed in Cyprus. This discovery marks the first instance of Diaphorina citri in European Union (EU) territory, posing a new threat to an otherwise HLB-free Mediterranean and EU citrus production area.

HLB, also known as greening or yellow dragon disease, is caused by the bacteria Candidatus Liberibacter. Historically, the Mediterranean and the EU have been the only major citrus production regions without HLB, but recent events have raised concerns about the potential introduction of this destructive disease.

Two primary factors contribute to this heightened concern:

1. Expanding Vector Population: Trioza erytreae, the vector insect responsible for transmitting the African strain of HLB, has been expanding in northern Spain and along Portugal’s Atlantic coast. While this strain is considered less destructive than its Asian counterpart, it remains a threat.

2. Diaphorina citri’s Arrival: Diaphorina citri, the most efficient Asian psyllid carrier of the aggressive and lethal Asian strain of HLB, has now been detected in EU territory. The European and Mediterranean Plant Protection Organization (EPPO) confirmed the presence of Diaphorina citri in Cyprus, specifically in the municipality of Asómatos (Limassol district). This discovery raises concerns due to the vector’s potential to spread the disease further.

Cyprus now faces the urgent need to implement eradication measures against this quarantine insect to prevent the introduction and spread of HLB. Considering the severity of the situation, Intercitrus, the interbranch organization representing the Spanish citrus sector, has called upon the European Commission (EC) to investigate the origin of the outbreak and provide supervision and financial support for necessary actions.

To address this critical issue, Intercitrus and other stakeholders have urged:

1. Strengthened Prevention Measures: Immediate reinforcement of prevention measures and research efforts for biological control against these vectors is essential, especially considering the lack of effective insecticides authorized in the EU. Researchers are actively exploring patterns and varieties resistant or tolerant to the disease.

2. Enhanced Field Controls: Improved field controls are crucial for the early detection of HLB and its vectors.

3. Strict Border Controls: Stringent border controls are necessary to prevent the entry of HLB or its vectors into European citrus farming. The EC is encouraged to consider measures similar to those implemented by other countries, such as the United States, Australia, and Japan, to control the introduction of plant material in passenger luggage.

The consequences of HLB’s introduction into European citrus farming could be dire. Diaphorina citri, native to Asia, is notorious for propagating the most destructive strain of HLB. Once infected, citrus trees inevitably die within a maximum of eight years. Spain’s citrus sector, characterized by its smallholder structure and strict environmental and phytosanitary regulations, would face significant challenges in combatting this disease.

This situation underscores the importance of a coordinated and proactive response at regional and EU levels. The threat of HLB is not limited to Cyprus; it has the potential to affect citrus production across Europe. It is imperative that the EU, citrus-producing regions, and researchers work collaboratively to address this looming crisis. Time is of the essence, and decisive action is essential to safeguard the future of European citrus cultivation.

Information from: EPPO and Fresh Plaza