Xylella Outbreak Confirmed in Calabria, First Pauca Strain Outside Puglia

Italian authorities have confirmed the first known outbreak of Xylella fastidiosa subspecies pauca outside Puglia.

Authorities detected the bacterium about a month ago in seven olive trees in Taurianova, southern Calabria. The Plant Health Service laboratory of the Lombardy region, which serves as Calabria’s official phytosanitary laboratory, obtained the initial results.

The samples were subsequently sent to the National Reference Laboratory at the Bacteriology Section of CREA-DC in Rome, which confirmed that the trees were infected with the same Xylella subspecies responsible for the devastating outbreak that has affected millions of olive trees in Puglia.

A wide-ranging monitoring operation is underway in the Taurianova area, where authorities identified a cluster of six infected olive trees, along with a seventh positive tree a few hundred meters away.

Following the discovery, regional authorities activated a broad containment and eradication plan. In a video published on social media, Calabria’s regional agriculture councilor, Gianluca Gallo, said the plan aims to eradicate the infection and prevent the bacterium from spreading further.

The regional government allocated €300,000 to address the emergency phase.

As required under European Union regulations, authorities established a 50-meter infected zone around each positive tree. Within those areas, authorities are removing infected plants and other species known to be susceptible to the bacterium.

Authorities established a 2.5-kilometer buffer zone around the infected areas. Intensified surveillance, sampling and vector-control measures are being carried out there to determine whether the bacterium has spread beyond the known outbreak.

The program calls for thousands of tests across the demarcated area. The potentially affected plant population is estimated at about 80,000 plants, covering roughly 1,200 hectares of olive groves and another 500 hectares of surrounding land.

Because not every plant potentially susceptible to Xylella can be tested, the survey is designed statistically. A negative result cannot prove that the bacterium is entirely absent, but it can indicate, with a defined level of confidence, that any undetected infection remains below a very low threshold.

The plan requires landowners or the Regional Plant Health Service to destroy removed plants on site. Before removal, treatments against insect vectors must be carried out to prevent them from dispersing during the operations.

The roots of infected trees must also be completely removed or, where that is not possible, devitalized to prevent regrowth.

Non-infected monumental olive trees may be exempted from removal under derogations provided by European Union regulations.

The regional plan also introduces measures to monitor and control Philaenus spumarius, the meadow spittlebug and one of the main vectors of Xylella.

Across the demarcated area, local authorities, farmers and nursery operators will be required to implement measures to reduce vector populations and limit the risk of further transmission.

The plan also sharply restricts plant movement and wood transport. For new planting within the infected zone, only olive cultivars considered resistant or tolerant may be used, including Leccino, Lecciana, Leccio del Corno and Favolosa.

The outbreak has raised widespread concern because of Calabria’s crucial role in Italian olive oil production.

Calabria has more than 180,000 hectares of olive groves, accounting for roughly 17 percent of Italy’s olive-growing area. The region produces about 30,000 to 35,000 tons of olive oil in an average year and ranks among the country’s three largest producing regions, alongside Puglia and Sicily.

Nearly 80,000 farms grow olives in Calabria, while roughly one-third of the region’s olive-growing area is managed organically.

Coldiretti, Confagricoltura and other associations representing farmers, olive growers and millers have welcomed the plan announced by regional authorities.

The next few weeks will be crucial in determining the outbreak’s actual extent. Surveillance results are expected to show whether the seven positive olive trees represent a localized outbreak or whether the bacterium has already spread beyond the currently identified sites.

Even if no additional positive plants are detected, surveillance will continue for several years. Under the regional plan, the demarcated area can only be lifted after four consecutive years without any further detection of the bacterium.