Evaluation of fungicides for management of boxwood blight caused by Calonectria spp. under field conditions in Northern Germany

Abstract Fungicide protection is the current approach for management of boxwood blight caused by Calonectria pseudonaviculata ( Cps ) and C. henricotiae Che ). However, published studies evaluating fungicides under field conditions have been focused on . The objective this study was to evaluate in Northern Germany where both were present. Three trials conducted between 2006 2016. In 2006, plants artificially inoculated with a conidial suspension, while infested soil plant debris added different as inoculum 2012 trial used again without further addition 2015. Fungicides applied one five times assessments done three six times, depending upon trial. highest level disease severity occurred 2015 (0.91), lowest (0.01). Among evaluated preventive sprays Cercobin FL, Switch, Harvesan, Pugil 75 WG, Dithane NeoTec Euparen M WG most effective, control above 65%. 2012, all treatments including Askon, Cabrio Top, Malvin Osiris showed > 75% control. 2015, Bayer Rosen-Pilzfrei Baymat Switch effective (> 82%). Extended in-season also observed some fungicides. Additionally, few that more than 1 year reduced effectiveness over time. This filled several major knowledge gaps especially regarding fungicide efficacy against thus provides crucial information developing chemical strategies.