Update on the situation of Pantoea stewartii subsp. stewartii in Italy
In Italy, bacterial wilt of maize (Zea mays) caused by Pantoea stewartii subsp. stewartii (EPPO A2 List) had been found in several regions where it was subsequently eradicated (EPPO RS 2020/120, RS 2021/201, RS 2022/065). It was found again in 2022-2024 in Emilia-Romagna region: in Ferrara and Ravenna provinces (where it was later eradicated), as well as in Bologna province where eradication measures are ongoing (RS 2022/131, RS 2025/151). The NPPO of Italy recently informed the EPPO Secretariat of the following findings as a result of official surveys. In all cases, phytosanitary measures are applied. They include the destruction of the infested maize plants and the plants in a 1.5m radius around infected plants, as well as investigation of parental lines.
Emilia-Romagna
During monitoring of maize crops between May and June 2026 in Emilia-Romagna region, suspected symptoms of P. stewartii subsp. stewartii were found. The pathogen was detected in Piacenza province, Comacchio municipality (Ferrara province) and Medicinia and Imola municipalities (Bologna province).
Friuli-Venezia Giulia
In September 2025, P. stewartii subsp. stewartii was detected on maize plants in the municipality of San Quirino (Pordenone province). Further testing on parental seeds and seeds from growing plants were negative. In December 2025, this outbreak was considered eradicated.
Lombardia
During official surveys in May and June 2026, P. stewartii subsp. stewartii was detected on one maize plant in the municipality of Asola (Mantova province) and six maize plants in the municipality of Novedrate (Como province) showing chlorotic leaves.
Veneto
P. stewartii subsp. stewartii was detected in symptomatic maize plants in Caorle and Torre di Mosto municipalities (Venezia province) in June 2025. These outbreaks were declared eradicated in June 2026.
In June 2026, P. stewartii subsp. stewartii was detected in Caorle, Eraclea and Torre di Mosto municipalities (Venezia province) and Cologna Veneta municipality (Verona province). For the detections in seed crops, testing for the pathogen will also be conducted on maize cobs collected before harvest.
The pest status of Pantoea stewartii subsp. stewartii in Italy is officially declared as: Transient, actionable, under eradication.
Sources
NPPO of Italy (2025-06, 2025-07, 2025-10, 2025-12, 2026-06, 2026-07).