Influence of ‘Candidatus Liberibacter solanacearum’ infection on carrot root weight in Germany

Infection with the bacterium ‘Candidatus Liberibacter solanacearum’ (Lso) is suspected to cause severe damage in carrot leading to high carrot weight loss. This study investigates three main aspects: (i) whether there is a reduction of carrot root weight under field conditions due to Lso infection; (ii) the correlation between Lso infection rate in carrot plants and occurrence of the psyllid Trioza apicalis as the known vector for Lso in carrot, and (iii) the comparison between symptoms described in literature and observed symptoms associated with Lso infection. Therefore, field surveys were conducted from 2018 to 2021 on organically managed carrot fields in Lower Saxony, Germany. Two Rebell orange sticky traps were placed per field replaced on a weekly basis. Captured T. apicalis were morphologically identified and counted. Carrot plant samples were collected from T. apicalis infested fields. Discolouration of foliage and further symptoms on carrots were investigated. For detection of Lso in carrot plants and psyllids, the samples were analysed using PCR. The infection rate of carrot plants varied between 2.5% and 80% per field with low abundance of T. apicalis. Of the asymptomatic plants, 39.4% were infected with Lso, while 80.9% of the symptomatic plants were infected with Lso. The weight of Lso-positive carrot samples was not significantly reduced compared to Lso-negative samples. No economically relevant losses of carrot yield were reported by farmers participating in this study. This indicates that there was no effect of Lso infection on carrot root weight during this study. Of the symptoms associated with a Lso infection in carrots, only leaf discolouration could be confirmed. Overall, the bacterium is present in organically grown carrot plants in Lower Saxony but no major carrot root weight losses were observed

Interaction between Salmonella and Plants: Potential Hosts and Vectors for Human Infection

Fruits and vegetables are important for a healthy diet. However, when eaten raw and contaminated with human pathogens (HPs) they may cause a disease outbreak. Contamination with HPs can occur along the entire farm-to-fork production chain and Salmonella enterica is one of the most common foodborne pathogens. A range of biotic and abiotic environmental factors can influence the complex interactions between Salmonella and plants. Moreover, the outcome of experiments largely depends on the experimental design and parameters or methods employed, and on top, on the accompanying plant microbiome and the genetic equipment of the plant and the Salmonella strain. Particularly mobile genetic elements contribute to the diversification and adaptation of Salmonella to the plant environment. So far, little is known about the key processes and factors influencing the attachment and potential internalization of Salmonella in plants and the plant specific responses. It is therefore important to better understand the ecology of Salmonella in the soil and plant environment, in order to propose practicable recommendations for prevention of foodborne diseases. This also requires improved sensitivity and specificity of detection methods. In this chapter, we present the current knowledge, research needs, and methodology regarding the complex interactions between Salmonella and plants

Open Government Data: A Focus on Key Economic and Organizational Drivers

Grounding the analysis on multidisciplinary literature on the topic, the existing EU legislation and relevant examples, this working paper aims at highlighting some key economic and organizational aspects of the "Open Government Data" paradigm and its drivers and implications within and outside Public Administrations. The discussion intends to adopt an "Internet Science" perspective, taking into account as enabling factors the digital environment itself, as well as specific models and tools. More "traditional" and mature markets grounded on Public Sector Information are also considered, in order to indirectly detect the main differences with respect to the aforementioned paradig