Spain’s citrus industry is on alert after the first outbreaks of Citrus Yellow Vein Clearing Virus (CYVCV) were confirmed in the country. The virus primarily attacks lemon and bitter orange varieties and spreads via grafting, contaminated cutting tools, or insect vectors. While officials have not ruled out irregularly imported plant material as a source, the citrus sanitation and certification system will be reviewed.
The National Reference Laboratory for woody‑plant viruses, located at the Valencian Institute of Agricultural Research (IVIA), has identified 22 infected trees across eight commercial orchards in five districts of Castellón and Valencia provinces. The first alert came from the southern Tarragona province, where abnormal symptoms were observed on several lemon trees last autumn and later confirmed as CYVCV infections. Vicente Dalmau, head of the Regional Plant Health Service of the Generalitat Valenciana, said the virus was detected during an active search prompted by warnings from the Ministry of Agriculture and the Catalan government. “During September and October we carried out random surveys to identify tristeza virus strains, and after the alerts we analyzed the same samples for this modern virus,” he explained. The positive cases involve orange, mandarin and clementine varieties that showed no symptoms. Six nurseries now have affected plants or batches under confinement and are not authorized for commercial sale. “We have about 10,000 plants immobilized, while the Valencian region produces three to four million citrus seedlings annually, so the immediate impact on the nursery sector is limited,” Dalmau added.
The emergence of CYVCV exposes a weakness in the Citrus Health Improvement Program that IVIA launched fifty years ago in response to the severe impact of tristeza virus in the 1960s and 1970s. Using in‑vitro micro‑grafting of basal shoots, the program has produced more than 800 healthy varieties, resulting in over 200 million certified seedlings that reshaped Spain’s citrus landscape. Though the possibility that CYVCV entered Spain through irregularly imported material cannot be dismissed, Dalmau announced that “the entire citrus sanitation and certification system will undergo a thorough evaluation to apply corrective measures where necessary.”
Por el momento, hay seis viveros con algunas plantas o lotes afectados, que están confinados y no disponen de autorización para su comercialización
CYVCV belongs to the Potexvirus genus and was first identified in Pakistan in 1988. Since then it has spread to India, Turkey, China, Iran and South Korea, reached California in 2022 and Italy in 2024. Antonio Olmos, head of the National Reference Laboratory for woody‑plant viruses, said the true extent of the problem remains unknown. “We do not yet know how widely the virus has dispersed in our fields. So far it has been detected in various sites across the Valencian Community in orange, mandarin and clementine varieties that are generally asymptomatic. We have no data on its presence in lemon orchards in the region. Larger‑scale surveys are underway to assess the current situation as quickly as possible,” he said.
IVIA is developing and refining detection methods for laboratories, fields and nurseries, including a real‑time PCR assay validated to EPPO standards and being transferred to regional Plant Health Services. “In addition to tracing the origin of the isolates, we are conducting epidemiological studies, identifying vectors, evaluating transmission capacity and searching for lemon varieties with greater tolerance or resistance,” Olmos explained.
En el IVIA se está buscando material vegetal más tolerante o resistente en limonero
Preventive and containment measures have grow the top priority to avoid a massive spread that could heavily affect lemon production, the most economically vulnerable citrus species. The virus spreads through grafting, contaminated cutting tools and abundant insect vectors such as aphids (Aphis spiraecola, A. Gossypii) and the citrus whitefly (Dialeurodes citri). Because no curative treatment exists—an infected tree remains infected for life—official recommendations focus on hygiene and agronomic management. In areas where the virus has not yet been detected, Plant Health authorities advise using certified material subject to official control, avoiding uncertified plant material from commercial plots or other EU member states, conducting regular surveys for symptom emergence in orchards, nurseries and gardens (especially lemon, lime and bitter orange), applying phytosanitary interventions to reduce vector populations, practicing balanced irrigation and fertilization, managing growth to limit secondary shoots that attract aphids and whiteflies, removing weed reservoirs, and disinfecting tools with a 1:9 bleach solution for at least five minutes, 70‑100 % isopropyl alcohol, hydrogen peroxide or quaternary ammonium compounds.
Nurseries must strengthen biosecurity, keep production under physical protection with double doors, enforce strict personnel entry restrictions and increase insecticide treatments against vectors. Plant Health services also require traceability records for nursery batches and phytosanitary passports for propagation material, noting that the introduction of citrus propagation material from third‑country sources is generally prohibited throughout the European Union. Any suspected symptoms should be reported immediately to local agricultural offices or the Plant Health Service.
Typical leaf symptoms of CYVCV on lemon, lime and bitter orange include pronounced chlorosis along leaf veins, especially secondary veins, leaf cupping and blistering, occasional ring‑shaped chlorotic spots and darkening or necrosis of veins on the leaf underside.
In lemon trees, fruit symptoms such as malformations, reduced size and quality have also been reported. Severe infections can weaken trees and lower yields. Symptom severity varies with variety, viral strain and environmental conditions, with milder expression during summer heat.
