Differential responses of Uruguayan onion cultivars to bacterial bulb rot and leaf blight caused by Pantoea spp. and Burkholderia sp

Bacterial diseases caused by Pantoea spp. are an emerging constraint for onion production in Uruguay. This study evaluated bacterial aggressiveness and the response of Uruguayan onion cultivars and breeding lines. P. ananatis MAI6032, P. agglomerans MAI6045, and Burkholderia sp. B.1.4 were the most aggressive isolates. No significant differences in foliar lesion length were detected among onion cultivars, while other cultivated Allium species showed minimal or no symptoms. Field trials identified ‘INIA Casera’ and ‘INIA Nácar’ as less susceptible among short-day cultivars, and ‘Pantanoso del Sauce’, ‘INIA Naqué’, and ‘INIA Santina’ among intermediate- and long-day cultivars.