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Crops as hosts of Curtobacterium flaccumfaciens pv. flaccumfaciens in Brazil

Daniele Maria do Nascimento: São Paulo State University

<div>Knowledge of ecological niches of <em>Curtobacterium flaccumfaciens </em>pv.<em> flaccumfacien</em>s (Cff), causal agent of bean bacterial wilt, is essential for the efficient management of the disease. This study evaluated its survival in the phylloplane and rhizosphere of black oat, rattlepod, common bean, sunflower, maize, pearl millet, forage turnip and soybean. The aerial part of the plants was inoculated by spraying bacterial suspension (10<sup>7</sup> CFU.mL<sup>-1</sup>) of Feij-2628A strain, 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 weekly, for 42 days, with three plants of each species being collected for each evaluation. After the processing of the soil and phylloplane samples, 100 μL of the supernatant were plated in NSARF semi-selective medium, followed by incubation (28 °C/96 h), and qualitative evaluation of Cff colonies. Feij-2628A strain survived for 42 days in the phylloplane of all species evaluated, except in rattlepod (14 days) and maize (28 days). In the rhizosphere, Cff survived for 21 days in soybean, 28 days in black oat, 35 days in pearl millet, maize and forage turnip, and for 42 days in the other species. These results can help producers in the selection of crops for rotation with common bean.</div>