Successful establishment and growth of newly planted trees in the landscape is dependent on many factors. Weed pressure and water conservation are typically achieved with either organic mulches or chemical herbicides applied over the root ball of the newly planted tree. In the landscape, eliminating turfgrass from the root zone of trees may be more complicated than resource competition. Studies have shown that tall fescue (Festucaarundinaceae Schreb.) has allelopathic properties on pecan trees [Caryaillinoiensis (Wangenh.) K. Koch]. Well-manicured tall fescue turf in the landscape may have negative effects on the establishment and growth of landscape trees as well. A study was designed to examine the effects of popular turfgrasses on the growth of newly planted pecan and redbud (Cerciscanadensis L.). Results demonstrate that the presence of turfgrass over the root zone of trees negatively impacts tree growth. Through two growing seasons, every growth parameter measured on redbuds (caliper, height, shoot growth, shoot dry weight, root dry weight, leaf area, and leaf weight) was significantly reduced by the presence of turf. However, the warm season bermudagrass [Cynodondactylon (L.) Pers.] was less inhibitied than the cool season grasses. The affects of turfgrass on pecan growth was less significant; however, caliper, leaf area, and root dry weight were significantly reduced when grown with turf.
Jason J. Griffin, William R. Reid, and Dale Bremer
Ross Braun, Jack Fry, Megan Kennelly, Dale Bremer, and Jason Griffin
Zoysiagrass (Zoysia sp.) is a warm-season turfgrass that requires less water and fewer cultural inputs than cool-season grasses, but its widespread use by homeowners in the transition zone may be limited because of its extended duration of brown color during dormancy. Turf colorants are an option for improving zoysiagrass winter color. Our objective was to quantify the impact of colorants applied in autumn at three application volumes on persistence of green color on lawn-height ‘Chisholm’ zoysiagrass (Zoysia japonica). The commercial colorants Green Lawnger, Endurant, and Wintergreen Plus were applied in Oct. 2013 in Manhattan, KS, and Haysville, KS, in solutions with water at 80, 160, or 240 gal/acre at a 1:6 dilution (colorant:water) and evaluated through late 2013 and Spring 2014. Tall fescue (Festuca arundinacea), a cool-season turfgrass commonly used in home lawns in the transition zone, was included for comparison. Persistence of green color increased with application volume, but differences among colorants were limited. Colorants provided acceptable color (i.e., a visual rating ≥6 on a 1 to 9 scale) for 55 to 69 days at 80 gal/acre, 69 to 118 days at 160 gal/acre, and 118 to 167 days at 240 gal/acre. Compared with tall fescue, colorant-treated zoysiagrass had significantly higher color ratings for 98 to 112 days at 80 gal/acre, 112 to 154 days at 160 gal/acre, and 138 to 154 days at 240 gal/acre. Colorants increased turfgrass canopy temperature by up to 12.1 °F, but did not accelerate spring green-up. Duration of acceptable color on ‘Chisholm’ zoysiagrass lawns can be enhanced by increasing colorant application volume.
Jason J. Griffin, William R. Reid, and Dale J. Bremer
Establishment and growth of eastern redbud (Cercis canadensis L.) and pecan [Carya illinoinensis (Wangenh.) K. Koch] were studied where soil surfaces were either covered with each of three common turfgrass species or maintained free of vegetation by the use of an herbicide or an organic mulch layer. Turf species included two cool-season grasses, tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.), and the warm-season bermudagrass [Cynodon dactylon (L.) Pers.]. After two growing seasons, tree caliper of both species was 100% greater in turf-free plots compared with trees in the cool-season grass plots. Root weight of pecans increased nearly 200% when turf was eliminated, and redbud root weight increased nearly 300%. Top weight of redbuds increased 300% and pecans increased 200% when turf was eliminated. Total leaf weight of both species was 300% greater in the turf-free plots, and leaf area increased 200% in both species. Net photosynthesis of redbud trees tended to be higher in the plots without turfgrass, and cool-season grasses inhibited photosynthesis to a greater extent than the warm-season grass. Foliar tissue analysis revealed that nitrogen (N) and potassium (K) were the only elements that increased in concentration when turf was eliminated. However, nutrient concentrations in all treatments were within recommended standard ranges. The results suggest that landscape tree establishment and growth are greatly inhibited by the presence of cool-season turfgrasses and that the inhibition may be more complicated than resource competition.
Dale J. Bremer, Steven J. Keeley, and Abigail Jager
Urbanization is increasing the land area covered with turfgrasses, which may affect water quantity and quality. Our objective was to understand lawn-watering habits of homeowners in Olathe and Wichita, KS, based on home value, home age, and lot size. Surveys were mailed to 9992 homeowners in Olathe and 15,534 in Wichita, with a return rate of 12%. Owners of more expensive and/or newer homes were more likely to water frequently, water on a routine schedule, feel it was important to have a green lawn, have an in-ground sprinkler system, and sweep or blow grass clippings and lawn care products off impervious surfaces. Owners of less expensive and/or older homes were more likely to never water or water infrequently, water based on the lawn’s appearance rather than on a routine schedule, consider it less important to have a green lawn; not have an in-ground sprinkler system, and leave grass clippings and lawn care products on impervious surfaces rather than blowing them off. A small percentage of homeowners who swept or blew clippings and/or lawn-care products did so into streets/storm drains. Owners of less expensive and/or older homes were somewhat more likely to engage in this practice. Educational efforts to improve lawn water conservation should be concentrated on homeowners in more expensive and/or newer homes because they water more frequently and routinely. Efforts to protect surface water quality should include homeowners of less expensive and/or older homes.
Qi Zhang, Jack Fry, Channa Rajashekar, Dale Bremer, and Milton Engelke
Cell membranes play an integral role in freezing tolerance. The objectives of this study were to quantify polar lipids in cold-tolerant ‘Meyer’ zoysiagrass (Zoysia japonica) and cold-sensitive ‘Cavalier’ zoysiagrass (Zoysia matrella) and to evaluate their potential role in freezing tolerance. Grasses were acclimated outside and sampled once monthly between October and January to determine freezing tolerance and lipid composition in rhizomes. Lowest LT50s (temperature resulting in 50% survival) were observed in November for ‘Cavalier’ (−8.5 and −9.6 °C in 2005 and 2006, respectively) and December for ‘Meyer’ (−16.2 and −15.4 °C in 2005 and 2006, respectively). The most abundant lipids in zoysiagrass rhizomes were monogalactosyl diacylglycerol, digalactosyl diacylglycerol, phosphatidylcholine, phosphatidylethanolamine, and phosphatidic acid, which comprised 90% of the polar lipids. Differences in lipid contents and double bond indices (DBI) were detected between ‘Meyer’ and ‘Cavalier’ during cold acclimation, but there were no consistent relationships between lipid classes or DBI and freezing tolerance in zoysiagrass.
Kenton W. Peterson, Jack D. Fry, and Dale J. Bremer
‘Meyer’ zoysiagrass (Zoysia japonica Steudel) is commonly planted on home lawns and golf courses in the transition zone; however, poor shade tolerance limits its widespread use. This study was conducted to determine changes and differences in growth among selected Zoysia cultivars and progeny under a natural shade environment over a 3-year period in the transition zone. The study was initiated in June 2010 at the Rocky Ford Turfgrass Research Center in Manhattan, KS. Soil type was a Chase silt loam (fine, montmorillonitic, mesic, Aquic, Argiudoll). Zoysia genotypes were sodded in 0.37-m2 plots and arranged in a randomized complete block with five replications under silver maple (Acer saccharinum L.) shade that resulted in a 91% reduction in photosynthetically active radiation (PAR). Genotypes included ‘Zorro’ [Z. matrella (L.) Merrill], ‘Emerald’ [Z. japonica × Z. pacifica (Goudswaard) Hotta & Kuroki], ‘Meyer’, Chinese Common (Z. japonica), and experimental progeny Exp1 (Z. matrella × Z. japonica), and Exp2 and Exp3 [(Z. japonica × Z. pacifica) × Z. japonica]. ‘Zorro’ and ‘Emerald’ experienced winter injury, which negatively affected their performance. Tiller numbers decreased 47% in ‘Meyer’ from June 2010 to June 2012, but declines in [(Z. japonica × Z. pacifica) × Z. japonica] progeny were only 1% for Exp2 and 27% for Exp3, and both Exp2 and Exp3 maintained high percent green cover throughout the study. In general, by the third year of evaluation, progeny of [(Z. japonica × Z. pacifica) × Z. japonica] had higher quality ratings and higher tiller numbers than ‘Meyer’ and may provide more shade-tolerant cultivar choices for transition zone turf managers.
Ross C. Braun, Jack D. Fry, Megan M. Kennelly, Dale J. Bremer, and Jason J. Griffin
In the transitional climates, warm-season turfgrasses are more heat and drought resistant and require fewer pesticide and fertilizer inputs than cool-season turfgrasses, but an extended winter dormancy period in warm-season turfgrasses makes them less attractive. Our objective was to evaluate color intensity and persistence of colorants applied at two volumes, once or sequentially, on buffalograss (Buchloe dactyloides) maintained at 2.5 inches and zoysiagrass (Zoysia japonica) maintained at 0.5 inch. Field studies were conducted in Manhattan, KS, and Haysville, KS, from Oct. 2013 to May 2014 on dormant ‘Sharpshooter’ and ‘Cody’ buffalograss and ‘Meyer’ zoysiagrass. The colorants Green Lawnger, Endurant, and Wintergreen Plus were applied at 100 or 160 gal/acre in autumn (single application) or autumn plus midwinter (sequential application). Every 2 weeks, visual turf color was rated on a 1 to 9 scale (9 = best) with ratings based on the intensity of the color, not the color (hue) of green. Few differences in color persistence occurred among colorants, but color persisted longer at the higher spray volume. In general, buffalograss receiving a single autumn colorant application had acceptable color (i.e., a visual rating ≥6) for 55–70 days at 100 gal/acre or 55–88 days at 160 gal/acre. Zoysiagrass receiving a single autumn colorant application had acceptable color for 56–97 days at 100 gal/acre or 97–101 days at 160 gal/acre. Across all sites, a sequential midwinter application applied at 160 gal/acre on buffalograss and both application volumes on zoysiagrass provided acceptable green turf color from that point until spring green-up. Most buffalograss plots receiving the sequential midwinter application at 100 gal/acre had acceptable color from that point until spring green-up. Winter color of buffalograss and zoysiagrass can be enhanced by colorant application, and a longer period of acceptable color can be achieved by applying at a higher volume or by including a sequential midwinter treatment.
Dale J. Bremer, Steven J. Keeley, Abigail Jager, Jack D. Fry, and Cathie Lavis
Urbanization is increasing the land area covered with turfgrasses, which may have implications for water quantity and quality. The largest sector of turfgrass is residential lawns. Our objectives were to compare lawn-irrigation perceptions, knowledge, and behaviors of residential homeowners with and without in-ground sprinkler systems (IGS and NIGS, respectively); homeowners were surveyed in three Kansas cities, each with distinctive water quantity and quality issues. Surveys were mailed to 15,500 homeowners in Wichita, 10,000 in Olathe, and 5000 in Salina; the return rate was 11% to 13%. Homeowners with IGS watered more frequently than NIGS; 67% to 90% of IGS and 19% to 31% of NIGS homeowners watered two to three times per week or more. More IGS homeowners watered routinely and applied the same amount of water each time than NIGS homeowners, who mostly watered and adjusted watering amounts based on lawn dryness. More IGS than NIGS homeowners wanted their lawn green all the time, followed lawn-care guidelines, and considered their neighborhood appearance important. Among IGS homeowners, 41% to 54% claimed to know how much water their lawns required compared with only 29% to 33% of NIGS homeowners. However, 65% to 83% in both groups did not know how much water they applied when they irrigated. About 7% to 9% of homeowners swept or blew clippings or lawn-care products into streets or storm drains; this percentage was unaffected by whether they had IGS or not. All homeowners’ lawn irrigation knowledge and habits must be improved to help conserve water and protect water quality, but educational efforts should concentrate on IGS homeowners because they water more frequently.
Kemin Su, Dale J. Bremer, Richard Jeannotte, Ruth Welti, and Celeste Yang
Cool-season turfgrasses may experience heat stress during summer. Hybrid bluegrasses (HBGs), crosses between kentucky bluegrass [KBG (Poa pratensis L.)] and native texas bluegrass (Poa arachnifera Torr.), have improved heat tolerance but the mechanisms of heat tolerance are poorly understood. Our objectives were to quantitatively profile membrane lipid molecular species in three cool-season turfgrasses exposed to optimal (22/15 °C, 14/10 h light/dark) and supra-optimal temperatures (35/25 °C and 40/30 °C, 14/10 h light/dark). Grasses included a low heat-tolerant tall fescue [TF (Festuca arundinacea Schreb. ‘Dynasty’)], a mid-heat–tolerant KBG (‘Apollo’), and a heat-tolerant HBG (‘Thermal Blue’). At high temperature, glycolipid digalactosyldiacylglycerol (DGDG) in HBG was 12% and 16% greater than in KBG and TF, respectively, and the ratio DGDG to monogalactosyldiacylglycerol was 19% and 44% greater in HBG than in KBG and TF, respectively. Greater heat tolerance in HBG and KBG was associated with higher contents of phosphatidylethanolamine and phosphatidylglycerol, and with reduced overall unsaturation compared with TF. Overall, 20 lipid molecular species were present in greater amounts and another 20 species in lesser amounts in HBG and KBG than in TF. Results suggest 40 membrane lipid molecules are potential biomarkers for heat tolerance and that compositional changes in membrane lipids in response to heat contribute to differences in heat tolerance among cool-season grasses.
David O. Okeyo, Jack D. Fry, Dale J. Bremer, Ambika Chandra, Dennis Genovesi, and Milton C. Engelke
Zoysiagrass (Zoysia spp.) is recognized for its low requirements for pesticide and fertilizer input, but Meyer (Z. japonica Steud.), the cultivar commonly used in the transition zone of the United States, is slow to establish. We evaluated new zoysiagrass progeny for stolon growth characteristics and rate of establishment and determined the relationship between stolon growth characteristics and coverage. ‘Meyer’, DALZ 0102 (a Z. japonica), and 18 progeny from crosses of ‘Emerald’ (Z. japonica × Z. tenuifolia Willd. ex Thiele) or a Z. matrella (L.) Merr. × Z. japonica were planted as 6-cm diameter plugs on 30.5 × 30.5-cm centers in 1.5 × 1.5-m plots in 2007 and as single 10-cm diameter plugs in 1.2 × 1.2-m plots in 2008 in Manhattan, KS. Data were collected weekly on number of stolons initiated per plug, stolon elongation, and number of stolon branches. Two researchers rated coverage visually near the end of each growing season. Rate of stolon initiation ranged from 2.2/week to 8.6/week. Elongation rate ranged from 18.8 to 65.1 mm/week. At 11 weeks after planting in 2007, four of 18 progeny had superior coverage to ‘Meyer’; at 11 weeks after planting in 2008, 13 of 18 progeny had superior coverage to ‘Meyer’. Rate of stolon initiation was positively correlated (P < 0.01) with zoysiagrass coverage (r = 0.66, in 2007; r = 0.94 in 2008); likewise, stolon elongation was positively correlated with coverage in 2007 (r = 0.52, P < 0.01) and 2008 (r = 0.53, P < 0.05). Stolon initiation or elongation could be used in short-term evaluations to predict rate of zoysiagrass coverage from plugs. Greater stolon initiation or elongation of experimental some zoysiagrass progeny makes them promising for alternatives to ‘Meyer’ for overcoming slow establishment rates.