Field and laboratory studies were conducted to evaluate the K retention properties of several resin-coated (RC), sulfur-coated (SC), and plastic-coated (PC) K fertilizers. Substantial differences in K release were found among the controlled-release K materials, based both on the K content of `Tifgreen' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burt-Davvy] clippings and on direct measurement of K remaining in fertilizer granules in the field over time. One SC material appeared to release K too rapidly, and one RC material appeared to release K too slowly to be useful for providing extended plant-available K to turfgrass. The other sources appeared to have release characteristics that would be favorable for turfgrass maintenance. Because differences in K release were observed among the sources, a laboratory method for assessing K release would be useful. Toward this-end, models were developed relating K retention of sources in hot water (70C) to K retention under field conditions.
George H. Snyder and John L. Cisar
Glyphosate traditionally has been used by growers and landscapers as a nonselective herbicide; however, selective uses do exist. The use of glyphosate to control weeds in dormant and actively growing bermudagrass (Cynodon dactylon) is an example of selective weed control. Several ornamentals, including conifer species, have been known to exhibit good tolerance to over-the-top applications of glyphosate. Unfortunately, little published information exists on rates of glyphosate that may be used on specific ornamental species. The objective of this research was to determine the tolerance levels of three juniper species [‘Blue Pacific’ shore juniper (Juniperus conferta), ‘Blue Star’ juniper (Juniperus squamata), and ‘Parsoni’ juniper (Juniperus davurica)] to various rates of glyphosate. Research conducted in 2004 and 2005 indicated that injury to three juniper species did not exceed 23% with glyphosate rates up to 2.5 lb/acre.
James N. McCrimmon
Limited information is available concerning the mineral nutrient content of different turfgrass species. There is a need to develop sufficiency ranges for turfgrasses under various management programs. The nutrient concentration of a turfgrass provides an indication of the nutrient status and quality of the turf. A study was conducted to assess the mineral nutrient composition of selected turfgrass species and cultivars. Plant tissue samples of the following turfgrasses were collected: creeping bentgrass, Agrostis palustris Huds. `Penncross'; bermudagrass, Cynodon dactylon (L.) Pers. `NuMex Sahara', `Santa Ana', `Texturf 10', and Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy `Tifgreen', `Tifway'; perennial ryegrass, Lolium perenne L. `Medalist × Blend'; St. Augustinegrass Stenotaphrum secundatum (Walt.) Kuntze `Seville'; and zoysiagrass, Zoysia japonica Steud. `El Toro' and Zoysia japonica × Zoysia tenuifolia Willd. ex Trin. `Emerald'. Three samples of each cultivar were collected, washed with deionized water for 30 s, and dried in a forced-air oven at 70°C for 72 hr. Plant samples were analyzed for both macronutrient and micronutrient concentration. For the bermudagrass cultivars, the concentrations of potassium (K) and magnesium (Mg) were less than 20.0 g·kg-1 and 2.0 g·kg–1, respectively, and less than known sufficiency levels. `Tifway' and `Texturf 10' had lower nitrogen (N) concentrations than other bermudagrasses. `Penncross' and `Medalist X' had the highest N concentrations. Zoysiagrass had low concentrations of N, phosphorus (P), calcium (Ca), K, and Mg. The concentration of copper (Cu) was low for zoysiagrass and three bermudagrass cultivars (`Texturf 10', `Tifgreen', and `Tifway'). There were differences among the turfgrasses for manganese (Mn) and zinc (Zn) concentrations.
Michael T. Deaton and David W. Williams
Common bermudagrass (Cynodon dactylon) and hybrid bermudagrass (Cynodon dactylon var. dactylon × C. transvaalensis) often are used for athletic fields as a result of their wear tolerance and recuperative ability. A wear tolerance study was conducted May 2007 through Nov. 2008 in Lexington, KY. Plots were managed as athletic turf and simulated traffic was applied during the Kentucky high school football seasons. The cultivars Quickstand, Tifway 419, Riviera, and Yukon grown in a sand-based medium were evaluated. Trinexapac-ethyl (TE) was applied at label rates and frequencies or left untreated. Overseeding treatments were perennial ryegrass (Lolium perenne) at 0, 546, and 1093 lb/acre pure live seed. Traffic treatments were applied with a Brinkman traffic simulator three times per week, once each Monday, Wednesday, and Friday, without regard to soil moisture status or weather for the periods 10 Sept. to 2 Nov. 2007 and 12 Sept. to 14 Nov. 2008. In both years of the study, the main effect of cultivar was significant (P < 0.05) in traffic tolerance (‘Tifway 419’ = ‘Riviera’ > ‘Quickstand’ = ‘Yukon’). Overseeding at the medium and high rates also provided significantly greater turf cover for the coarse-textured, more open cultivars (Quickstand and Yukon) over the fine-textured, more dense cultivars (Riviera and Tifway 419). Applications of TE did not significantly improve tolerance to simulated athletic traffic in either year of the study regardless of cultivar or overseeding treatment. Within the parameters of this study, data indicate that only cultivar has significant effects on tolerance to simulated traffic on a sand-based field. Overseeding treatments for the fine-textured, more dense cultivars and TE applications on sand-based field systems had no positive significant effects on tolerance to simulated traffic.
John Wells, Jiyu Yan, Melissa Riley, Suresh Samala, and Vance Baird
Bermudagrass (Cynodon dactylon) cultivars may exhibit increased tolerance to cold following periods of exposure to moderately cold temperature (i.e., acclimation). We are evaluating biochemical changes and the regulation of gene expression in two cultivars—'Midiron' and U-3—during this acclimation period. Total membrane lipid fatty acids per unit of total lipids (MLFA/TL; μg·mg–1) increased in crowns over the 4-week exposure to chilling temperatures (8C day/2C night). Of the fatty acids comprising 95% of total MFLA, concentrations of short-chain and saturated FAs declined significantly while unsaturated longer-chain FA concentration increased. As a result, the double bond index (percent of each FA x number of double bonds in the FA) increased during the period of low temperature exposure, indicative of increasing membrane fluidity. Changes in MFLA were evident as early as 4 days following exposure to chilling temperatures. Identification of mRNA species expressed in response to low temperature utilized differential display-PCR. Initial screening with paired T11N1N 2 3'-anchor and 5'-random decamer primers has identified transcripts differentially expressed as early as 23 h post-exposure and was maintained for at least an additional 36 h. Isolation, reamplification, and cloning of these identified PCR products is in progress.
A. Shiferaw, M.W. Smith, R.D. Eikenbary, and Don C. Arnold
Perennial legumes ground covers were evaluated in pecan (Carya illinoinensis) orchards to supply nitrogen and increase beneficial arthropods. Ground covers were `Kenland' red clover (Trifolium pratense), `Louisiana S-1' white clover (Trifolium repens), a mixture of these two legumes, or bermuda grass (Cynodon dactylon), each in 5 ha plots. Nitrogen was applied at 0-200 kg·ha-1 N in 50 kg intervals to bermuda grass plots, and was omitted on the legumes. Aphids feeding on the legumes attracted lady beetles; however, lady beetle populations in the tree canopies were not affected by ground cover treatment. The most abundant lady beetle species in legumes were Coleomegilla maculata lengi (77%) and Coccinella septempunctata (13%); whereas, dominant species in tree canopies were Coleomegilla maculata lengi (33%). Olla v-nigrum (20%). Cycloneda munda (18%) and Coccinella septempunctata (15%). Several other beneficial arthropods were sampled in legumes and tree canopies. Aphid populations feeding on pecans were low (peak population ≈ 2 aphids/leaf), and not affected by ground cover treatment. Legumes supplied the equivalent of applying 68-156 kg·ha-1 N.
Pendimethalin and oxadiazon are used commonly to control crabgrasses (Digitaria spp.) in tall fescue (Festuca arundinacea Schreb.) and common bermudagrass [Cynodon dactylon (L.) Pers.]. A field experiment was conducted for 2 years to determine if reduced pendimethalin and oxadiazon application rates would control large crabgrass [D. sanguinalis (L.) Sco.] effectively in tall fescue and common bermudagrass. Oxadiazon applied at 1.1 kg a.i./ha in each of two applications at a 60-day interval (less than recommended rate) effectively controlled large crabgrass (≥93%), regardless of turfgrass species. Pendimethalin applied at 1.1 kg a.i./ha in each of two applications controlled large crabgrass in common bermudagrass effectively (≥90%) but not large crabgrass in tall fescue (47%). The difference in pendimethalin performance between the two species was attributed to the ability of common bermudagrass to compete more successfully than tall fescue with large crabgrass during late summer. Chemical names used: 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethy1)-l,3,4-oxadiazol-2-(3 H)-one (oxadiazon); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).
Charles H. Peacock and Paul F. Daniel
Initial release of N from waste materials used as natural organic N carriers for turfgrass may be slow due to the need for microbial degradation. In a greenhouse study, `Rebel' tall fescue (Festucau arundinacea Schreb.) and `Tifway' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] growth response to a natural organic fertilizer (Turf Restore) amended or not amended with a soil-derived microbiological inoculum were compared with soluble urea using sterilized and nonsterilized soil. No interactions of soil sterilization and fertilizers were noted at 19 days after treatment (DAT). Urea fertilizer increased tall fescue growth rates by 68% in the nonsterilized soil and 126% in the sterilized soil compared to rates for turf grown with inoculated Turf Restore. Nitrogen uptake rate was 419% higher with urea-fertilized turf in the sterilized soil than for turf fertilized with inoculated Turf Restore. Soil sterilization at 33 DAT no longer affected turf response, but turf growth rate was 133% higher and N uptake 353% higher with urea fertilization than with inoculated Turf Restore. Infection of the plants with Rhizoctonia spp. at 72 DAT was unaffected by fertilizer treatments. Bermudagrass response was similar to that of tall fescue. Growth rate was 67% and N uptake 51% higher with urea than with Turf Restore through 17 DAT, regardless of inoculant addition. Amendment of the natural organic fertilizer Turf Restore with a soil-derived biological inoculant did not enhance turf growth rate or N uptake nor impact infection with Rhizoctonia spp.
M.S. Flanagan, R.E. Schmidt, and R.B. Reneau Jr.
The “heavy fraction” portion of a municipal solid waste separation process was evaluated in field experiments as a soil amendment for producing turfgrass sod. Soil organic matter and concentrations of extractable NO3-N, P, K, Ca, and Zn in the soil increased with addition of heavy fraction. Soil incorporation of heavy fraction resulted in greater air, water, and total porosity and lower bulk density of a loamy sandy soil. .Sod strength measurements taken 8.5 and 9.5 months after seeding were higher for Kentucky bluegrass (Poaprutensis L.) grown in heavy-fraction-amended topsoil than for turf grown in topsoil only. The use of this by-product may reduce the time required to produce a marketable sod. Soil incorporation of heavy fraction did not influence post-transplant rooting of Kentucky bluegrass sod but enhanced rooting of bermudagrass [Cynodon dactylon (L.) Pers.] sod at the highest rate evaluated. Results of these studies suggest that the use of heavy fraction for sod production may provide cultural benefits in addition to reducing the volume of solid waste deposited in landfills.
Chunhua Liu, James J. Camberato, S. Bruce Martin, and Amy V. Turner
Rough bluegrass (Poa trivialis L.) is being utilized more frequently to overseed bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] putting greens and rapid seed germination is necessary for successful establishment. Cultivar and seed lot differences in germination rate and sensitivity to cold may exist. Germination of 10 rough bluegrass cultivars/seed lots was examined in growth chambers at 12-hour day/12-hour night temperatures of 25/15, 20/10, 15/5, and 10/0 °C, and on a bermudagrass putting green at three overseeding dates. Differences in germination among cultivars and seed lots were minimal at 25/15 or 20/10 °C, but substantial at lower temperatures. When seeded on the bermudagrass putting green, differences in germination among cultivars/seed lots were greater at the last seeding date (average daily max./min. of 16/2.7 °C), than at the first seeding dates (average daily max./min. of 21/6.1 °C). Use of blends of several cultivars or seed lots is suggested to ensure the successful establishment of rough bluegrass when overseeding at low temperatures.