Cultivar Selection, Cultural Management Practice, And Fungicide Application Influence Leaf Spot And Dollar Spot On Ultradwarf Bermudagrass

In the southern United States, putting greens are commonly grassed with an ultradwarf bermudagrass (UDB) [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] cultivar. However, these turfgrasses generate profuse amounts of thatch, which leads to increased pressure of diseases such as leaf spot, caused by Bipolaris cynodontis (Marignoni) Shoemaker, and dollar spot, caused by Sclerotinia homoeocarpa F.T. Bennett. This 2-yr field study evaluated the effects of (i) cultivar selection ('Champion' and 'MiniVerde' UDB cultivars), (ii) cultural management practice (standard weekly applications of vertical mow [VM]; weekly applications of VM with once monthly substitutions of slice, spike, and scarify practices; and once monthly applications of slice, spike, and scarify practices alone), and (iii) fungicide application (application of fungicide and no application of fungicide) on leaf spot and dollar spot of UDB putting green turf. Leaf spot severity (LSS) was assessed by a visual estimation of percent symptomatic turf area (0-100%). Dollar spot incidence (DSI) was assessed as the number of dollar spot foci present. At most rating periods during active infection, MiniVerde had reduced LSS and DSI compared with Champion. Standard VM practices resulted in the greatest LSS and DSI. Once monthly substitutions of spike and scarify practices in weekly VM regimes reduced LSS and DSI compared with standard VM practices. The least LSS and DSI were observed with once monthly applications of alternative slice, spike, and scarify practices. Applications of fungicides reduced LSS and DSI compared with no application of fungicides.