Dollar Spot Resistance among Blends of Creeping Bentgrass Cultivars

Abstract

Disease is a major problem in creeping bentgrass (Agrostis stolonifera L.) on golf course putting greens. Genetic composition and uniformity of host populations can affect disease development. This study was conducted to determine the effects of blending creeping bentgrass cultivars on dollar spot (caused by Sclerotinia homoeocarpa F. T. Bennett) severity. ‘Penn A‐4’, ‘Crenshaw’, ‘L‐93’, ‘Mariner’, and ‘Penncross’ were planted in monostands or as two‐way or three‐way blends in a completely random design with three replications on a sand‐based putting green in the field at College Station, TX. Disease severity was determined by the number of infection centers and by total blighted area. Crenshaw was most susceptible, L‐93 most resistant, and all other cultivars were moderately resistant to dollar spot in monostands. Cultivar susceptibility in monostands to S. homoeocarpa was representative of each cultivars contribution to dollar spot severity in blends. In blends, L‐93 suppressed, whereas Crenshaw increased dollar spot. Penncross, Penn A‐4, and Mariner did not affect dollar spot severity across all blend combinations. Number of infection centers and infected area pooled across all monostands were similar when compared to all two‐ and three‐way blends indicating that dollar spot activity in blends was a compromise between resistance levels of individual cultivars. Two‐way blends of Penn A‐4, L‐93, Mariner, or Penncross with Crenshaw, however, resulted in 46 to 67% fewer infection centers and 71 to 98% less blighted area, when compared to the Crenshaw monostand. These data indicated that blending a resistant cultivar with a susceptible cultivar reduced dollar spot severity in the blended population.

Response of Bentgrass Cultivars to Sclerotinia homoeocarpa Isolates Representing 10 Vegetative Compatibility Groups

“…Most bentgrass cultivars are susceptible to dollar spot, caused by S. homoeocarpa, but there are significant differences in their response to dollar spot (Baldwin and Newell, 1992;www.ntep.org/data/bt03g/ bto3g_05-2/bt03g05t19.txt;verified 19 Jan. 2006). Dollar spot severity can be reduced by management practices such as blending seeds of resistant and susceptible cultivars (Abernathy et al, 2001). This disease is the most prevalent and economically important turf disease in North America, particularly on intensively managed golf course putting greens and closely mown fairways (Couch, 1995;Vargas, 1994).…”

“…Dollar spot severity can be reduced by management practices such as blending seeds of resistant and susceptible cultivars (Abernathy et al, 2001). Cultural practices include removal of foliar dew by mowing or poling (Williams et al, 1996), and applications of late spring N fertilizer or multiple applications of composts (Boulter et al, 2002).…”

The Dollar Spot Susceptibility of 25 Bentgrasses is Consistent across Five States in the Central USA

“…are commonly used on golf courses in the Central USA, but dollar spot (caused by species within the genus Clarireedia gen. nov.) seriously injures surfaces not protected with fungicide. Cultivars vary in susceptibility to dollar spot (Abernathy et al, 2001; Brede, 2007; Koch and Kerns, 2012; Ryan et al, 2012; Settle et al, 2001), and host resistance is an effective way to limit disease development, fungicide application frequency, and selection of fungicide resistant dollar spot isolates. Superintendents and scientists often use data from the National Turfgrass Evaluation Program (NTEP) to select less‐susceptible cultivars, but data is not available for all locations.…”

Novel action thresholds of a logistic regression model to forecast dollar spot on bentgrasses

“…The severity of dollar spot epidemics can be affected by the host species or cultivar (Ryan et al., 2012; Settle et al., 2001). While colonial bentgrass ( A. capillaris L.) and velvet bentgrass ( A. canina L.) are typically less susceptible to dollar spot than creeping bentgrass (Belanger et al., 2004; Chakraborty et al., 2006; Koeritz & Stier, 2009 ), there is a wide range of dollar spot susceptibility within creeping bentgrass cultivars (Abernathy et al., 2001; Chakraborty et al., 2006; Golembiewski & Danneberger, 1998; NTEP, 2014; Warnke, 2003). Reduced susceptibility to dollar spot in creeping bentgrass is quantitatively inherited and affected by environment (Bonos, 2006, 2011; Bonos et al., 2003).…”