Survival of Curtobacterium flaccumfaciens pv. flaccumfaciens in the phyllosphere and rhizosphere of crops

Knowledge of the ecological survival niches of Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), the causal agent of bean bacterial wilt, is essential for the efficient disease management. Our study evaluated the survival of Cff in the phyllospheres and rhizospheres of barley, black oat, canola, common bean, forage turnip, maize, pearl millet, ryegrass, sorghum, soybean, sunflower, velvet bean, wheat and white oat planted in a greenhouse. The aerial parts of the plants were inoculated by spraying a bacterial suspension (107 CFU.mL−1) from the strain Feij. 2628A, which is resistant to rifampicin and pathogenic to common bean. The soil of the pots was infested with 200 mL of the same suspension. Cff survival was evaluated every seven days for 70 days, and the survival periods were confirmed by selecting strains from all samples and performing PCR with specific primers. Cff survived for at least seven days in the phyllosphere, and 21 days in the rhizosphere of all evaluated crops. Based on our results, barley, black oat, canola, forage turnip, maize, pearl millet, ryegrass, sorghum, soybean, sunflower, velvet bean, wheat and white oat can be potential asymptomatic hosts for Cff, and their cultivation in succession with common bean is not recommended in areas with a history of bacterial wilt occurrence.