Black shank caused by Phytophthora nicotianae is responsible for serious yield and quality reduction in tobacco production. Application of effective fungicides continues to be a significant component in developing integrated disease management programs. Studies were conducted in 2010-2013 to determine the efficacy and application methods of a new fungicide, QGU42 (Zorvec™, oxathiapiprolin), for management of black shank under field conditions. QGU42 was applied using different methods and application rates ranging from 2.4-38.6 fl oz/acre were evaluated. In the experiment conducted in 2010, application of QGU42 (2.4 fl oz/acre) prior to transplanting in conjunction with applying QGU42 at 19.2 fl oz/acre in transplant water and 2.4 fl oz/acre at 1st cultivation and layby was the most effective in disease reduction. In 2011, the two most effective treatments were: 1) application of QGU42 through transplant water (4.8 fl oz/acre) and at 1st cultivation and layby (38.6 fl oz/acre); 2) application of QGU42 (4.8 fl oz/acre) prior to transplanting in conjunction with applying QGU42 at 19.2 fl oz/acre at 1st cultivation and layby. In 2012, QGU42 applied prior to transplanting (4.8 fl oz/acre) and at 1st cultivation and layby (9.6 fl oz/acre) was among the most effective treatments. In 2013, application of QGU42 through transplant water at 38.6 fl oz/acre, or QGU42 applied through transplant water at 19.2 fl oz/acre and at planting and layby, reduced disease significantly compared with the non-treated control. These treatments also increased tobacco yield significantly compared to the non-treated control. Across the experiments conducted in the 4 years, QGU42 was effective in reduction of black shank at a rate as low as 2.4 fl oz/acre and appeared to be more effective than mefenoxam in managing this important disease. (Reprinted with permission)