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Made available in DSpace on 2022-04-28T19:49:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Survival niches for phytopathogenic bacteria are important for disease management. We study the survival of Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), the causal agent of bacterial wilt in common bean and bacterial tan spot in soybean, in the soil. While Cff strains from common bean already have several studies, the ecology of soybean strains needs more information. We used the strain Feij.2628A from common bean, and CffR1, Cff2R, and Cff4R from soybean. The soils were infested with bacterial suspension (107 CFU.mL−1) from each of the strains. For experiments under laboratory conditions, they were incubated in BOD incubator (biochemical oxygen demand) at 20 °C. Under natural field conditions, pots were maintained in the field without supplementary irrigation. The survival of Cff strains was evaluated every seven days until they were not detected. The identity of the bacterium was confirmed in all treatments by PCR. Under laboratory conditions, the survival period of Feij.2628A ranged from 140 to 154 days, and between 77 to 119 days for the soybean strains. Feij.2628A and Cff1R survived for a maximum of 91 days in soil with higher clay content, under natural field conditions. Cff survival was negatively influenced by high temperatures, low soil moisture, and precipitation in some treatments. These results demonstrated the potential survival of Cff strains from common bean and soybean in the soil, being potential inoculum sources for subsequent cultivations of these crops. Fallow periods ranging from three to four months may reduce the amount of inoculum in soils under these conditions. Department of Plant Protection School of Agriculture São Paulo State University (Unesp), Avenida Universitária Department of Plant Protection School of Agriculture São Paulo State University (Unesp), Avenida Universitária

Made available in DSpace on 2021-06-25T10:49:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) A crop rotation system can reduce phytopathogen inoculum, and consequently reduce the incidence and severity of disease. Bean bacterial wilt is an important disease and several crops can act as inoculum sources for Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff). The aim was to evaluate the influence of crop rotation systems on 10 common bean cultivars against bacterial wilt. Experiments were located in two different areas in Brazil (2012), cultivated under a no-tillage system and with a history of the disease. The evaluated rotation systems were black oat, wheat and fallow followed by common bean. After harvest, 10 dry bean cultivars were sown, together with a fallow area. Disease incidence and severity were assessed at 45, 60 and 80 days after sowing. Also evaluated were four agronomical parameters: pod numbers, grain numbers, total weight of grains per plant and weight of 100 grains. Epiphytic and endophytic colonization by Cff was evaluated in black oat and wheat, and in crop debris. The rotation systems significantly influenced the incidence and severity of bacterial wilt in common bean cultivars in both areas and negatively affected the four agronomic parameters. The cultivars BRS Campeiro, BRS Estilo, IPR Tuiuiú, IPR Tangará and IPR Campos Gerais presented low severity and incidence of the disease and higher productivity. Cff strains were recovered from black oat, wheat and crop debris. Our results reinforce the importance of planting non-Cff host crops in rotation systems with common bean, as well as planting cultivars with a level of resistance to bacterial wilt. Departamento de Proteção Vegetal Faculdade de Ciências Agronômicas (FCA) Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Avenida Universitária, 3780 Departamento de Proteção Vegetal Faculdade de Ciências Agronômicas (FCA) Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Avenida Universitária, 3780