Assessing the Pathogenic Ability of Ralstonia pseudosolanacearum ( Ralstonia solanacearum Phylotype I) from Ornamental Rosa spp. Plants

( phylotype I) isolates found in stunted, yellowing, and wilted ornamental rose ( spp.) were assessed for their pathogenic ability in two rose cultivars (cv. "Armando" and cv. "Red Naomi") and in four solanaceous crops: tomato ( cv. "Money Maker"), tobacco ( cv. "White Burley"), eggplant ( cv. "Black Beauty") and sweet pepper ( cv. "Yolo Wonder"). Significant differences were observed in susceptibility between the two rose cultivars as well as between the two modes of inoculation performed. The cultivar "Armando" was significantly more susceptible than cultivar "Red Naomi," exhibiting higher disease severity and incidence. Similarly, stem inoculation after wounding was found to be significantly more effective than soil drenching, resulting in higher disease severity. Additionally, a temperature dependency in susceptibility was observed for both cultivars irrespective of the mode of inoculation, however, this was significantly more pronounced upon soil drenching. The solanaceous crops all showed to be susceptible to the . isolates originated from the spp. plants. Furthermore, both rose cultivars were able to harbor symptomless infections with other . and isolates than those isolated from rose. Our results clearly demonstrated that latent infections in a rose cultivar such as cv. "Red Naomi" do occur even at temperatures as low as 20°C. This latency poses high risks for the entire floricultural industry as latently infected spp. plants are propagated and distributed over various continents, including areas where climatic conditions are optimal for the pathogen.