Maximizing ‘Cimarron’ Little Bluestem Establishment as Secondary Rough for a Golf Course

Native grasses are an important design component in secondary roughs of golf courses due to minimal maintenance requirements and aesthetics. However, problems with seed germination and subsequent establishment limit their use. Two 2-year studies on ‘Cimarron’ little bluestem were conducted in 2000 and 2002 at Mississippi State University. In each study, seed was planted at five rates: 12.7, 25.4, 38.1, 51, and 63.4 lb of pure live seed (PLS) per acre. Visual percent cover was recorded each month after planting (MAP). The seeding rate of 12.7 lb PLS/acre may not be acceptable for secondary roughs, since coverage was only 6.7 and 4%, respectively, at 2 MAP. This would most likely result in establishment failure during rainfall events. By the end of the first 2-year trial, there were no significant differences among coverage rates ≥ 25.4 lb PLS/acre. By the end of the second 2-year study, there was no difference among seeding rates. Based upon this study, rates at or above 25.4 lb PLS/acre would be recommended. Though these higher ‘Cimarron’ seeding rates benefit first year establishment, 100% cover is still unlikely and establishment will require a minimum of 2 years. Early management response to weed competition may be a key component for successful establishment of ‘Cimarron’ little bluestem in golf course secondary roughs. Introduction Native grasses continue to be an important component in the design, establishment, and maintenance of golf courses and many of the top golf courses in the US have planted native grasses (Fig. 1). There were an estimated 13,951 golf courses in the United States in 1990 covering an estimated 1.3 million acres of maintained turfgrass (1). These numbers indicate tremendous potential for additional utilization of native grasses on golf courses. The southern and middle Atlantic states are among the states having the greatest density of golf course facilities (1). Native grasses have been utilized in secondary roughs and natural areas of golf courses because they offer desirable characteristics in terms of size, shape, and color. In addition, they are adapted to a wide range of soils and climates, require minimal to no maintenance, and can provide habitat for many forms of wildlife (2,10). Such areas are established by various means ranging from hand planting to hydro-mulching. However, germination and subsequent establishment are still a major problem and stand failures are common (9). These problems range from weeds to improper variety selection and seeding rate. 2 August 2007 Applied Turfgrass Science Mitchell and Britton (8) and the USDA (11) discuss managing weeds to establish and maintain warm-season grasses for forage, but little is known about the management of weeds in native grasses within the golfing environment. At least within forages, competition or interference from weeds often limits stand establishment of perennial warm-season grasses or may cause complete stand failure (8). Early establishment of native grasses could be vulnerable to weeds, especially warm-season annual weeds (8). Little information is provided for weed control in little bluestem (8,11), especially during establishment. Broadleaf weed control using 2,4-D on little bluestem during and after the four-leaf stage was cited, but more research is needed for grass weed control. Additionally, some degree of playability is necessary after establishment emphasizing the importance of open voids in the canopy of clump-forming native grasses. However, these open voids between native grass clumps may serve as invasion areas for weeds. More weed control research is needed regarding the establishment, maintenance, and playability of native grasses in the golf environment, especially herbicides with existing turf labels. In the eastern United States, common, warm-season, native grasses used in low maintenance areas include big bluestem (Andropogon gerardii Vitm.), broomsedge (Andropogon virginicus L.), indiangrass [Sorghastrum nutans (L.) Nash], little bluestem [Schizachryium scoparium (Michx.) Nash], and switchgrass (Panicum virgatum L.). Little bluestem may be more desirable for secondary golf roughs for finding and playing errant shots when compared to taller native grasses. For example, big bluestem, indiangrass, and switchgrass can reach heights of 3, 2, and 6 ft by year 2, respectively (4). Broomsedge is similar to little bluestem in height, but has shown poor germination during the first year of establish (4,5). Thus, little bluestem was chosen for this study. Even though little bluestem is shorter at maturity, height could still be a problem and some mowing may be necessary. It is probable that it will not compare to the playability of bermudagrass [Cynodon dactylon (L.) Pers.] in similar areas. Although this study deals more with establishment issues, more research is needed regarding management and playability of these grasses for secondary roughs. Despite its positive characteristics, establishment of little bluestem tends to be more difficult than taller grasses like switchgrass. This may be due to the selection of inappropriate varieties or seeding rates (4, 5). ‘Cimarron’ little bluestem was chosen for this study based upon its previous performance (4,5) and adaptation (11). ‘Cimarron’ had higher stand coverage than ‘Aldous,’ ‘Blaze,’ ‘Camper,’ and ‘Itasca’ little bluestems in July on soils with a pH near 5.2 (4). On soils with a pH near 6.5, ‘Aldous’ little bluestem had higher stand coverage (21.7 % compared to 6.9 % for ‘Cimarron’) (5). It should that although both varieties were planted at recommended seeding rates in both studies, neither was considered acceptable (4,5). Despite this second year difference (5), ‘Cimarron’ summer colors were more in the gray (chroma 2) range which may contrast better with green bermudagrass turfs. Winter colors for the two grasses are similar, although ‘Cimarron’ tended to be more yellow or less red compared to ‘Aldous’ little bluestem (4,5). However, sheath colors on dormant ‘Cimarron’ Fig. 1. Early development of a little bluestem [Schizachryium scoparium (Michx.) Nash] stand on a golf course which illustrates how these areas may come in to play as secondary roughs. 2 August 2007 Applied Turfgrass Science little bluestem were closer to dormant broomsedge leaf colors, which seem to be desirable winter colors. All little bluestem varieties in the studies conducted by Maddox et al. (4,5) tended to be upright in stature, although with low stand coverage lodging potential was probably not optimum. The USDA (11) shows similar ranges of adaptation in the southeastern United States for ‘Aldous,’ ‘Cimarron,’ and ‘Pastura’ little bluestems, but no information on other little bluestem varieties. Recommended seeding rates for little bluestem are highly variable. Recommendations by USDA (11) were based upon the number of seeds per square foot. However, most seed companies currently recommend rates based on pounds of pure live seed (PLS) per acre. Aside from seed company sales booklets, little information is available on seeding rates and web-source recommendations are highly variable, ranging between 6.7 (Sharp Brothers Seed Company, personal communications, 2006; Linda Conway Deuver, personal communications, 2006) and 28 lb/acre (James C. Grimes, personal communications, 2006). This variability has led to some confusion about what seeding rates are necessary for successful little bluestem establishment. The objective of this study was to evaluate the influence of seeding rate and weeds upon the establishment of ‘Cimarron’ little bluestem for golf course secondary roughs. Planting of Studies Establishment studies were conducted at the Mississippi State University Plant Sciences Research Center, Starkville, MS. The soil was a Marietta fine loam (fine loamy, siliceous, active, thermic Fluvaquentic Eutrochrept). Soil samples were taken in July 2000 and 2002 and analyzed (Table 1). Since little bluestem was native to the area, research plots were fumigated with methyl bromide at 653 lb/acre prior to planting to prevent germination of any preexisting little bluestem or weed seed. Irrigation was supplied as needed during germination. No irrigation was provided during the second year of either trial. Table 1. Soil analyses for the Marietta fine loam (fine loamy, siliceous, active, thermic Fluvaquentic Eutrochrept) at the Plant Science Research Center study area, Mississippi State University, Starkville, MS. x Soil samples were taken in July of each year prior to study initiation and analyzed by the Mississippi State University Extension Service Soil Testing Lab, Mississippi State, MS. The first study was planted on 2 August 2000. ‘Cimarron’ little bluestem seed was obtained from Hamilton Seed Company (Elk Creek, MO). Seed germination was 86%, purity was 70%, 0.05% weed seed, and no dormant seed were reported. The second study was initiated on 9 August 2002. ‘Cimarron’ seed was obtained from Bamert Seed Company (Muleshoe, TX) and featured 88% germination, 44.4% purity, 1.1% weed seed, and no dormant ‘Cimarron’ seed. Both lots were planted within 6 months of seed testing. In each study, seed was planted at five rates: 12.7, 25.4, 38.1, 51, and 63.4 lb PLS/acre. The lowest rate of 12.7 lb/acre was based upon the recommendation of Stock Seed Farms (Murdock, NE) in promotional data released in 1992. Rates currently recommended by Stock Seed Farms are similar at 14.5 lb PLS/acre. The seed was mixed with 0.33 pints of damp sand to assist with separating the seed, which has long hairs, and as a guide for coverage uniformity, since it contrasted with the existing soil surface. Once thoroughly mixed, the seed-sand mix was dispersed by hand over each plot using the sand as a guide for coverage uniformity. Sand coverage was light and did not affect soil texture. Study yearx pH % OM P K Ca Mg Zn S