Sod Farms Research Articles

Off-site transport of fungicides with runoff: A comparison of flutolanil and pentachloronitrobeneze applied to creeping bentgrass managed as a golf course fairway

Flutolanil and pentachloronitrobenzene (PCNB) are fungicides used to control or suppress foliar and soil borne diseases in turf and ornamental crops. On golf courses, sports fields, sod farms and commercial lawns these fungicides are used as preventive treatments to combat snow mold, brown patch and fairy ring. Depending on the aquatic organism, flultolanil and PCNB are considered to be moderately to highly toxic. Therefore runoff or drift from treated areas may be hazardous to organisms in adjacent aquatic sites. This research compared the transport of flutolanil and PCNB with runoff from turfgrass managed as a golf course fairway. The quantity of fungicide transported with runoff and observations reported with the chemographs followed trends in agreement with the chemical properties of the compounds. Overall, we observed the rate of transport for flutolanil was greater than PCNB, which contributed to the more than 12 times larger load (µg/m2) of flutolanil transported off-site at the conclusion of the simulated storm runoff. A better understanding of the off-site transport of pesticides with runoff is needed to make informed decisions on management practices to reduce potential adverse effects on non-target organisms, as well as maintain control of targeted pests in the area of application. In addition, data obtained with this research can be used in model simulations to predict nonpoint source pollution potentials beyond experimental conditions.

Spatial and Temporal Distribution of Phyllophaga spp. Infesting Bermudagrass Stands in Oklahoma

Larvae of Phyllophaga spp. (Coleoptera: Scarabaeidae) are important direct and indirect turfgrass pests in the southern United States. Confirming the presence of these larvae is an important integrated pest management practice in turf production systems and determines the need for treatment. However, several different species (e.g., P. crinita, P. submucida, and P. crassissima) are known to occur within the same turfgrass stand, and each species has a different oviposition period. The objective of this study was to determine the spatial and temporal distribution of Phyllophaga spp. in intensely managed bermudagrass. During spring through summer of 2009, larvae were collected after harvesting bermudagrass turf from two sod farms in Oklahoma. The location of each grub was determined using global positioning system tracking. Identification of larvae was based on polymerase chain reaction amplification and sequencing of the cytochrome c oxidase I gene. Species spatial and temporal distribution patterns were analyzed by detrended correspondence analysis using CANOCO 5.04. Seven species of Phyllophaga were collected, and each study site contained at least one species that was not found at the other. Detrended correspondence analysis resulted in low β diversity values. Beta diversity reflects how far apart species are in the gradient of species composition. The low β diversity scores obtained in this study show that different species of Phyllophaga were present in no recognizable pattern of temporal or spatial distribution.

Evaluation of Herbicides and their Tank‐Mixes for Suppression of Bermudagrass in Zoysiagrass

Zoysiagrass (Zoysia spp.) is a popular turfgrass species for use on lawns, sod farms, and golf courses in the transitional and southern climatic zones of the United States. One common problem in managing zoysiagrass is the contamination and subsequent removal of bermudagrass (Cynodon spp.). Various herbicides and herbicide tank‐mixes may be utilized for bermudagrass control in zoysiagrass. Research was conducted in Fayetteville, AR, and Auburn, AL, to evaluate aminocyclopyrachlor, fluazifop, fenoxaprop, triclopyr, and their combinations for bermudagrass suppression in zoysiagrass. Fluazifop at 0.105 kg active ingredient (a.i.) ha–1 suppressed bermudagrass most, but this application caused unacceptable injury and quality reduction to zoysiagrass. Tank‐mixing fluazifop or fenoxaprop at 0.14 kg ai ha–1 with triclopyr at 0.56 kg acid equivalent (a.e.) ha–1 reduced zoysiagrass injury and improved turf quality over fluazifop or fenoxaprop alone. Fluazifop + triclopyr provided more bermudagrass suppression than fenoxaprop + triclopyr. Aminocyclopyrachlor (0.026 or 0.071 kg a.e. ha–1) did not reduce herbicide injury from fluazifop or fenoxaprop applications to zoysiagrass and did not provide significant bermudagrass suppression. Results suggest that fluazifop + triclopyr and fenoxaprop + triclopyr remain the best treatments for bermudagrass suppression in zoysiagrass because they provide bermudagrass suppression without reducing zoysiagrass quality.

Divot Resistance of Thick Cut Sod as Influenced by Preharvest Nitrogen and Sand Topdressing

Professional sports facilities in the United States install thick‐cut sod during the playing season. Field performance immediately after installation is primarily determined by maintenance practices at the sod farm. This research investigated the influence of six N programs (98–245 kg N ha−1 yr−1 applied in spring or fall) and two sand‐topdressing rates (0 and 8.5 kg m−2 yr−1) on Kentucky bluegrass (KBG, Poa pratensis L.). In 2013 and 2014, KBG was established from seed in September and grown for 7 mo at a commercial sod farm (Hammonton, NJ) and then transported as sod and grown for another 7 mo under six by two treatment combinations at University Park, PA. Sod was harvested 14 mo after seeding and evaluated for divot resistance, shear, and sod strength. In 2013, all N treatments were similar in divot resistance except the 245‐kg total N rate, which exhibited the lowest divot resistance. In 2014, the most divot resistance was observed with 49 kg N ha−1 applied three times in the spring (147 kg total N) or using the same N program with another 49 kg ha−1 applied in September (196 kg total N). Nitrogen treatments resulted in few meaningful differences in shear resistance. Sand topdressing affected divot and shear resistance differently. Topdressing reduced divot resistance by only 6% in 2014 and had no effect in 2013. Topdressing reduced shear resistance by averages of 21.6 and 28.4% in 2013 and 2014, respectively. Growers may improve the divot resistance of KBG sod by moderating N inputs.

Zoysiagrass (Zoysiaspp.) History, Utilization, and Improvement in the United States: A Review

Since its introduction into the United States in 1892, zoysiagrass (Zoysiaspp. Willd.) has made a tremendous impact on the US turfgrass industry. Three species of zoysiagrass [Z. japonicaSteud.,Z. matrella(L.) Merr., andZ. pacifica(Goudswaard) M. Hotta & S. Kuroki] collected from East Asia and the Pacific Islands were introduced into the United States and are used directly as turf or by turfgrass breeders in the development of advanced lines. Golf courses, lawns, grounds, sod farms, athletic fields, roadsides, and airports are some of the many locations where zoysiagrass is used. While almost 50 improved cultivars of zoysiagrass have been developed to date, active efforts to improve zoysiagrass further and expand its utilization are ongoing. These continued improvements in stress and pest tolerance allow for expanded use of this low‐input turf species. This review summarizes the history of zoysiagrass in the United States; summarizes species introduction and utilization; addresses and discusses strengths and shortcomings of the species; evaluates breeding history, methodology, and challenges; and suggests future prospects and potential for zoysiagrass.

Unmanned Aerial Vehicle to Estimate Nitrogen Status of Turfgrasses.

Spectral reflectance data originating from Unmanned Aerial Vehicle (UAV) imagery is a valuable tool to monitor plant nutrition, reduce nitrogen (N) application to real needs, thus producing both economic and environmental benefits. The objectives of the trial were i) to compare the spectral reflectance of 3 turfgrasses acquired via UAV and by a ground-based instrument; ii) to test the sensitivity of the 2 data acquisition sources in detecting induced variation in N levels. N application gradients from 0 to 250 kg ha-1 were created on 3 different turfgrass species: Cynodon dactylon x transvaalensis (Cdxt) ‘Patriot’, Zoysia matrella (Zm) ‘Zeon’ and Paspalum vaginatum (Pv) ‘Salam’. Proximity and remote-sensed reflectance measurements were acquired using a GreenSeeker handheld crop sensor and a UAV with onboard a multispectral sensor, to determine Normalized Difference Vegetation Index (NDVI). Proximity-sensed NDVI is highly correlated with data acquired from UAV with r values ranging from 0.83 (Zm) to 0.97 (Cdxt). Relating NDVI-UAV with clippings N, the highest r is for Cdxt (0.95). The most reactive species to N fertilization is Cdxt with a clippings N% ranging from 1.2% to 4.1%. UAV imagery can adequately assess the N status of turfgrasses and its spatial variability within a species, so for large areas, such as golf courses, sod farms or race courses, UAV acquired data can optimize turf management. For relatively small green areas, a hand-held crop sensor can be a less expensive and more practical option.

Carbon dioxide fluxes from Tifway bermudagrass: early results.

This paper reports for the first time preliminary data on carbon uptake of warm-season turfgrass at a well-managed sod farm in south central Georgia. It examines the changes in carbon uptake from one of the most widely used warm-season turfgrass cultivars in the world, Tifway Bermudagrass. It elucidates the roleof canopy density and light avalaibility on the net carbon uptake using the eddy-covariance technique. Preliminary evidence suggests that turfgrass is effective at sequestering carbon dioxide during the summer months even when the canopy is being reestablished following a grass harvest.

Influence of the Composted Liquid Manure on the Turf Growth of Zoysiagrass (Zoysiagrass japonica) and Soil Properties

This study was conducted to investigate the effects of composted liquid manure (CLM) on soil properties and turf quality of zoysiagrass. The CLMs were produced at 5 facilities for livestock excretions treatments located in Cheongwon, Gunwi, Iksan, Nonsan, and Yeoju in Korea, respectively. Field experiments were conducted at 5 golf courses and a sod farm located near each facility for livestock excretion treatments. Chemical fertilizer (CF) with N at 12 g m -2 year -1 and CLMs were applied four times, respectively. The constituents of the different CLMs were variable based on when and where the fertilizer was produced. Soil K content significantly increased when the soil was treated with CLMs. The soil treated with CF showed a higher content of total P than that treated with CLM. CF and CLMs treatments significantly increased the turf color index compared with control. Tiller density and shoot dry weight of fertilized plots were also higher than those of non-fertilized plots. However, there was no significant difference in turf color index and tiller density among plots treated by CLMs or CF. The results of this study demonstrated that CLMs could be a substitute for CF.

Tropical Sod Webworm (Lepidoptera: Crambidae): a Pest of Warm Season Turfgrasses

Larvae of Herpetogramma species (commonly called webworms, sod webworms, or grass webworms) are widely distributed throughout North America, Eurasia, Australia, New Zealand, Central and South America. Tropical sod webworm, Herpetogramma phaeopteralis (Guenee), larvae are among the most destructive pests of warm-season turfgrasses in the southeastern United States, Caribbean, and central America, especially on sod farms and newly established sod, lawns, athletic fields, and golf courses. Larval feeding affects the esthetics, vigour, photosynthesis, and density of turfgrass. Symptoms of infestation appear as notched and ragged grass blades with damaged areas in lawn appearing as small brown patches of closely mowed grass. Heavy infestations allow the ingress of weeds. Current control recommendations against tropical sod webworm include several cultural methods (including dethatching and cultivar selection) and the foliar application of chemical insecticides against larval stages. We summarize the seasonal biology, taxonomy, and IPM options of this important pest.

Biology and Management of the Sugarcane Beetle (Coleoptera: Scarabaeidae) in Turfgrass

The sugarcane beetle, Euetheola humilis (Burmeister), traditionally a pest of agricultural crops, has become a sporadic, but serious, pest of turfgrass on golf courses, athletic fields, home lawns, sod farms, and in pastures. Initially confined to the southeastern United States it has, in recent years, spread as far north as Maryland, west into Texas, and south into Florida. Little is known about sugarcane beetle ecology and behavior in turfgrass, including dispersal and feeding behaviors and the impact of damage to turf. Our research helped confirm previous ecological studies of this pest on sugarcane and other agronomic crops relative to life cycle, biology, and behavior to further develop better management approaches. Additional research concerning this insect is summarized and discussed relative to the current pest status of this insect and potential management strategies.

Detection of DNA and Ploidy Variation within Vegetatively Propagated Zoysiagrass Cultivars

Zoysiagrass (Zoysia sp.) is used as a warm-season turfgrass for lawns, parks, and golf courses in the warm, humid and transitional climatic regions of the United States. Zoysiagrass is an allotetraploid species (2n = 4x = 40) and some cultivars are known to easily self- and cross-pollinate. Previous studies showed that genetic variability in the clonal cultivars Emerald and Diamond was likely the result of contamination (seed production or mechanical transfer) or mislabeling. To determine the extent of genetic variability of vegetatively propagated zoysiagrass cultivars, samples were collected from six commercially available zoysiagrass cultivars (Diamond, Emerald, Empire, JaMur, Meyer, Zeon) from five states (Arkansas, Florida, Georgia, North Carolina, Texas). Two of the newest cultivar releases (Geo and Atlantic) were to serve as outgroups. Where available, one sample from university research plots and two samples from sod farms were collected for each cultivar per state. Forty zoysiagrass simple sequence repeat (SSR) markers and flow cytometry were used to compare genetic and ploidy variation of each collected sample to a reference sample. Seventy-five samples were genotyped and an unweighted pair group method with arithmetic mean clustering revealed four groups. Group I (Z. japonica) included samples of ‘Meyer’ and Empire11 (‘Empire’ sample at location #11), Group II (Z. japonica × Z. pacifica) included samples of ‘Emerald’ and ‘Geo’, Group III (Z. matrella) included samples of ‘Diamond’ and ‘Zeon’, and Group IV (Z. japonica) consisted of samples from ‘Empire’, ‘JaMur’, ‘Atlantic’, and Meyer3 (‘Meyer’ at sample location #3). Samples of ‘Empire’, ‘Atlantic’, and ‘JaMur’ were indistinguishable with the markers used. Four samples were found to have alleles different from the respective reference cultivar, including two samples of ‘Meyer’, one sample of ‘Empire’, and one sample of ‘Emerald’. Three of these samples were from Texas and one of these samples was from Florida. Three of the four samples that were different from the reference cultivar were university samples. In addition, one sample, Empire11, was found to be an octoploid (2n = 8x = 80). For those samples that had a fingerprint different from the reference cultivar, contamination, selfing, and/or hybridization with other zoysiagrasses may have occurred.

Modeling a phosphorus credit trading program in an agricultural watershed

Water quality and economic models were linked to assess the economic and environmental benefits of implementing a phosphorus credit trading program in an agricultural sub-basin of Lake Okeechobee watershed, Florida, United States. The water quality model determined the effects of rainfall, land use type, and agricultural management practices on the amount of total phosphorus (TP) discharged. TP loadings generated at the farm level, reaching the nearby streams, and attenuated to the sub-basin outlet from all sources within the sub-basin, were estimated at 106.4, 91, and 85 mtons yr−1, respectively. Almost 95% of the TP loadings reaching the nearby streams were attributed to agriculture sources, and only 1.2% originated from urban areas, accounting for a combined TP load of 87.9 mtons yr−1. In order to compare a Least-Cost Abatement approach to a Command-and-Control approach, the most cost effective cap of 30% TP reduction was selected, and the individual allocation was set at a TP load target of 1.6 kg ha−1 yr−1 (at the nearby stream level). The Least-Cost Abatement approach generated a potential cost savings of 27% ($1.3 million per year), based on an optimal credit price of $179. Dairies (major buyer), ornamentals, row crops, and sod farms were identified as potential credit buyers, whereas citrus, improved pastures (major seller), and urban areas were identified as potential credit sellers. Almost 81% of the TP credits available for trading were exchanged. The methodology presented here can be adapted to deal with different forms of trading sources, contaminants, or other technologies and management practices.

한국잔디 중지 변이개체와 연관된 RAPD-SCAR 마커

한국 잔디 신품종 개발 목적으로 전라남도 장성군 삼서면 일대 한국잔디 중지류 생산포장에서 선발한 생육 및 피복속도가 빠르고 밀도 또는 가을철 녹색기간이 긴 2개 우량계통을 대상으로 DNA 수준에서 기존 중지류 또는 한국잔디들과 차이를 살펴보고 신품종 특이적으로 차이를 보이는 DNA 염기서열을 기반으로 RAPD-SCAR 마커를 개발하고자 본 연구를 실시하였다. RAPD 프라이머를 스크리닝 한 결과 N8021와 N8001 프라이머가 CY6069와 CY6097 품종 각각에 특이적인 DNA 절편을 약 600 bp와 700 bp 부근에서 발견할 수 있었다. 특이 밴드는 TA-cloning vector에 삽입 후 대장균에 형질전환하여 배양하였고, 이로부터 추출된 플라스미드 DNA의 염기서열 분석을 실시하여 최종적으로 중지류 신품종 특이 SCAR 마커 프라이머를 작성하였다. CY6069 선발 품종 특이 SCAR 마커(CY6069_550)는 다른 한국잔디 들잔디(야지), 한국잔디 중지, 갯잔디, 금잔디에서는 보이지 나타나지 않았던 식별 가능한 밴드를 보였고(550 bp), CY6097 선발 품종 식별을 위한 SCAR 마커(CNU70-6_1500)도 CY6097 계통에서만 특이적으로 나타나는 DNA 밴드를 약 700 bp 부근에서 증폭할 수 있었다. 형태 및 생육특성 차이와 함께 본 연구를 통해 개발된 RAPD-SCAR 마커를 활용하면 선발된 중지류 한국잔디 CY6069와 CY6097 계통을 실험실내에서 PCR을 통해 유전자원 식별 및 원산지 증명이 가능해졌고 영양번식을 통해 주로 번식하는 난지형 잔디 생산 포장에서 품종의 혼입으로부터 정확하게 분리해 낼 수 있을 것으로 판단된다. Two medium-leaf ecotypes (CY6069, CY6097) belonging to one species (Zoysia japonica) of Korean lawngrasses were selected in sod production fields in Jang Seong, Korea. They were reported to have distinct morphological and growth rate characteristics different from the preferred medium-leaf type zoysiagrass in Korea. This study was conducted to define further the genotypic difference at the molecular level and to develop DNA marker based on the specific DNA fragment. Polymorphic DNA fragments were first explored by using randomly amplified polymorphic DNA (RAPD) primers, which were then converted into PCR-based sequence characterized amplified region (SCAR) markers. The CY6069-specific primer set amplified about 550 bp successfully, while the CY6097 marker produced the expected 690 bp band, by which those markers were nominated by CY6069_550 and CY6069_690 SCARs, respectively. Together with the reported morphological and other phenotypic features, the SCAR markers confirmed in this study will be useful to identify those medium-leaf zoysiagrass genotypes when they are cultivated with other vegetatively propagated warm-season turfgrasses in sod farms.

First Report of Stubby Root Caused by Trichodorus obtusus on Zoysiagrass and Bermudagrass in South Carolina.

In September 2011, diagnostic samples were taken from 'Tifway' Bermudagrass (Cynodon dactylon × C. transvaalensis) tees and from 'Emerald' Zoysia (Zoysia japonica) roughs of a golf course in Charleston, SC. Additional samples were taken from a sod farm located near Charleston, SC from a field of 'Empire' Zoysia. The soil was sandy loam and the samples were taken at a depth of 10 to 15 cm from symptomatic turf. Symptoms on bermudagrass and zoysiagrass included stubby roots and lightly to severely chlorotic or dead patches of irregular sizes and shapes. Nematodes were extracted by sugar centrifugal-flotation and counted. The predominant nematode species recovered was Trichodorus obtusus Cobb, 1913: syn. T. proximus Allen, 1957, n.syn. (3). Nematode densities (per 100 cm3 of soil) were 30 to 170 (average 94, n = 5) at the sod farm, and 30 to 230 (average 107, n = 7) at the golf course. This nematode has been reported as a pathogen of bermudagrass in Florida, where it is more damaging than Paratrichodorus minor, the other stubby root nematode commonly associated with turfgrass (1). In Florida, 120 T. obtusus individuals per 100 cm3 is considered high risk (2). We have encountered several additional samples from across South Carolina with comparable densities since our first diagnosis. Infested soil (94 individuals per 100 cm3) collected from the sod farm was put into columns and planted with 'Empire' sod and maintained in the greenhouse. After 140 days, the population density increased to an average of 230 individuals per 100 cm3. Plants were prone to wilting and new root growth showed symptoms similar to those observed in the field. Morphologic and morphometric identification of T. obtusus was made by examining male and female specimens in temporary water mounts. Males had ventrally curved spicules with three ventral precloacal papillae, with the posterior papilla just anterior to the head of the retracted spicules, one ventromedian cervical papilla anterior to the excretory pore, and tail with non-thickened terminal cuticle. Females had a deep, barrel-shaped, pore-like vulva, and one or two postadvulvar lateral body pores on each side. Males and females had distinctly offset esophagus. Females (n = 10) were 1,100 to 1,440 (1,250) μm long, body width 40 to 53 (45) μm, onchiostyle 63 to 75 (67) μm, and V 583 to 770 (673) μm. Males (n = 10) were 1,076 to 1,353 (1,222) μm long, body width 33 to 45 (39) μm, onchiostyle 62 to 69 (65) μm, and spicule 55 to 63 (59) μm. From individuals representing the two locations, an 898-bp section of the 18S rDNA region was sequenced using primers 37F (5'-GCCGCGAAAAGCTCATTACAAC-3') and 932R (5'-TATCTGATCGCTGTCGAACC-3') (4). A BLASTn search revealed no similar sequences to those of our two populations (Accessions JX289834 and JX279930). As such, it appears that these are the first sequences of this portion of the 18S rDNA for T. obtusus, although a different, non-overlapping portion of 18S was found in GenBank (AY146460) under the synonym T. proximus. To our knowledge, this is the first report of T. obtusus on zoysiagrass and the first report of the species on bermudagrass in South Carolina.

Sigurður Árni Þórðarson, Limits and Life: Meaning and Metaphors in the Religious Language of Iceland (Peter Lang: American University Studies, 2012)

“How did the people think, pray and make their lives meaningful in an isolated, underground sod farm in Iceland some centuries ago? In the summer everything enjoyed the bliss of creation in an endless bosom of light nights. Even the roofs turned green and yellow in response to the gentle strokes of the bright winds in a world of pulsing restlessness. Too soon the decay of fall set in. As prey to thundering storms of winter, the inhabitants of the small houses were left to some uncertain destiny. Above, the threats hovered in the sky. All around the forces of natural evil came closer. The world of myths creped into the minds and bones. Like a beast awakened from a summer trance, a precarious world suddenly echoed its appearance in the stories, the nannies’ warnings, the poems recited, and the religion practiced.” (p.51)

Sorption of the herbicide aminocyclopyrachlor by cation‐modified clay minerals

Aminocyclopyrachlor (6‐amino‐5‐chloro‐2‐cyclopropyl‐4‐pyrimidinecarboxylic acid), a new herbicide, was approved by US‐EPA (United States Environmental Protection Agency) in September 2010 for the control of broadleaf weeds, grasses, vines and woody species in non‐crops, turf, sod farms and residential areas. At typical soil pH levels, aminocyclopyrachlor is anionic. Anionic pesticides are generally weakly retained by most soil and sediment components and are subject to potential transport offsite. One strategy to minimize the risk of offsite transport associated with weakly sorbed, highly mobile pesticides is the application of these chemicals supported on a sorbent, such as modified clay minerals which contain exchangeable inorganic and organic cations. The aim was to determine the ability of unmodified and modified clay minerals to sorb aminocyclopyrachlor. Two montmorillonites (Ca‐Arizona montorillonite (SAz‐1) and Na‐Wyoming montmorillonite (SWy‐2)) were used as unmodified clay minerals and were also modified with an inorganic cation (Fe3+), soil constituents (ferrihydrite, humic acid) and organic cations (hexadecyltrimethylammonium (HDTMA), hexadimethrine, spermine). Greater sorption of aminocyclopyrachlor was observed in the sorbent–solution systems with lower pH values, presumably because of protonation of the herbicide anion at low pH and subsequent sorption of molecular species and cationic species. FeSWy‐2 (SWy‐2 montmorillonite saturated with Fe3+; system pH = 4.6) was the best sorbent for aminocyclopyrachlor (86% of applied). The best organo‐clay (SA‐HDTMA) (system pH = 6.1) sorbed 53% of the applied herbicide. Binary and ternary model sorbents (system pH > 6.7) did not sorb aminocyclopyrachlor. At the lowest pH value studied (2.8), the organo‐clay SW‐Sper was the best sorbent system for aminocyclopyrachlor. Our recommendation for the best adsorbent is the clay mineral modified with Fe3+, although at pH values <3, the use of the organo‐clay SW‐Sperm could be also convenient.

Assessment of Molecular Variation within ‘Raleigh’ St. Augustinegrass using Amplified Fragment Length Polymorphism Markers

St. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a popular turfgrass in the southern United States as a result of its superior shade tolerance and relatively low input requirements. However, it is the least cold-tolerant of commonly used warm-season turfgrass species. ‘Raleigh’, released in 1980, has superior cold tolerance and is adapted and widely used in U.S. Department of Agriculture hardiness zones 8 to 9. More than 25 years after its release, ‘Raleigh’ is still the industry’s standard in terms of cold tolerance. However, the original foundation and breeder stock fields of the cultivar have been lost, placing the integrity of the cultivar at risk. The objectives of this study were to investigate whether current ‘Raleigh’ production fields across the southern United States are true to the original source. In this study, 15 amplified fragment length polymorphism (AFLP) primer combinations were used to assess levels of genetic variability among three original stocks of ‘Raleigh’ and 46 samples obtained from sod farms and universities in six states. Genetic similarities among the original stocks were Sij = 1, whereas similarities between this group and all other samples ranged from 0.24 to 1.0. Results based on cluster analysis, principal coordinate analysis, and analysis of molecular variance (AMOVA) revealed separation between original stocks of ‘Raleigh’ and some commercial samples. Results from this study offer further evidence that molecular markers provide a useful and powerful technique for identity preservation of clonally propagated cultivars and the detection of genetic variants in sod production fields and turfgrass breeding programs.

Winter-applied Glyphosate Effects on Spring Green-up of Zoysiagrasses and ‘Yukon’ Bermudagrass in a Transition Zone

In transitional environments, turf managers and sod producers of warm-season grasses face the issue of winter annual weeds that can dominate dormant turf stands through the winter until late spring. The use of glyphosate to control weeds in dormant bermudagrass (Cynodon dactylon) has been well documented, but information is lacking about its effect on spring green-up of other warm-season grasses. A field study was conducted on two commercial sod farms in northern Italy (Expt. 1) to evaluate the effects of glyphosate applied on two different winter dates on weed control and spring green-up of ‘Zeon’ manilagrass (Zoysia matrella). A second study was carried out at the experimental agricultural farm of Padova University (Expt. 2) to assess the effects of a winter application of glyphosate on weed control and spring green-up of ‘Yukon’ bermudagrass and ‘Companion’ zoysiagrass (Zoysia japonica). Each experiment was conducted from Jan. to June 2011, and glyphosate was applied at 1.1 kg·ha−1 on 8 and 21 Feb. in Expt. 1 and on 8 Feb. in Expt. 2. Spring recovery was evaluated by periodical visual ratings of green turf cover and by collecting normalized difference vegetation indices (NDVIs). Weed injury was visually evaluated on all plots 7 weeks after the 8 Feb. glyphosate application. The visual ratings of green cover were strongly and positively correlated with NDVI measurements. Glyphosate applied in February as a single treatment effectively controlled winter weeds in ‘Zeon’ manilagrass (Expt. 1) and ‘Yukon’ bermudagrass (Expt. 2) without negatively affecting spring green-up. In contrast, spring green-up of ‘Companion’ zoysiagrass (Expt. 2) was delayed by the application of glyphosate.

Evaluation of Olive Mill Waste Compost as a Soil Amendment for Cynodon dactylon Turf Establishment, Growth, and Anchorage

A field study evaluated composted olive mill waste (OMC) as a soil amendment in Cynodon dactylon (bermudagrass; C4) turf establishment and maintenance. The study comprised two substudies, each of which had discrete goals: 1) an evaluation of OMC effects on overall bermudagrass growth over the course of 2.5 years when established by seed and subsequently from sprouting of existing rhizomes (2002 to 2004); and 2) a re-evaluation of OMC effects on bermudagrass establishment by seed (2003). Twenty-four plots (1.44 × 1.44 m) were filled with sandy-loam soil and supplemented with one of three OMC proportions (low= 12.5%, medium = 25%, and high = 50% by volume, indicated as substrates S:OMCL, S:OMCM, and S:OMCH, respectively), and non-amended soil served as a control (S). The study evaluated: 1) the substrate's chemical and physical characteristics, including bulk density, water retention curves, pH, and electrical conductivity (EC) measurements; 2) the establishment rate of C. dactylon, either by seed or by sprouting of existing rhizomes after dormancy as determined by measurements that included vertical detachment force (VDF), root growth, and substrate moisture; and 3) the growth rate of C. dactylon as determined through measurements of visual quality, clipping dry weight, root growth, and VDF. The results show that OMC decreased substrate pH in proportion to the OMC supplementation rate and increased EC only at the end of the study and only in the plots with the highest supplementation rate (S:OMCH). Water retention was improved by OMC incorporation except from S:OMCL, which increased water retention only at low tensions. Compared with soil alone, bulk density decreased by 13.5%, 19.7%, and 32.8% as the OMC rate increased, respectively, from 12.5% to 50%. The OMC rate of 50% v/v resulted in a minor reduction in plant visual quality during the cold periods but in a slight improvement during the warm periods. The clipping dry weights were increased by OMC amendments in 2003, which was considered a disadvantage because of the insignificant visual quality differences between substrates during the 2 study years. In 2004, the clipping yields were unaffected by OMC rate. Root dry weight response to OMC varied. For the highest OMC rate, root dry weight was lower during the cold and wet periods, greater during the first stages of bermudagrass establishment by seed, and similar compared with soil without OMC during turf establishment from the sprouting of existing rhizomes after dormancy. The highest OMC rate reduced resistance to vertical detachment force at four sampling dates (of six) during the 2002–2003 study, because the reduced root dry weight and/or increased moisture of the substrate facilitated bermudagrass detachment. In contrast, OMC-supplemented substrates resulted in increased VDF at the first sampling date of establishment both by seed (2003) and by rhizome sprouting after dormancy (2004). It was concluded that, when speedy establishment is imperative (such as in sod farms) or when irrigation is limited, an OMC rate of 50% by volume should be selected. In contrast, for sustainable bermudagrass growth, a rate of 12.5% by volume is preferred, because it increases the visual quality of the grass and root growth.

Phosphorus run-off assessment in a watershed

The Watershed Assessment Model was used to simulate the runoff volume, peak flows, and non-point source phosphorus loadings from the 5870 km(2) Lake Okeechobee watershed as a case study. The results were compared to on-site monitoring to verify the accuracy of the method and to estimate the observed/simulated error. In 2008, the total simulated phosphorus contribution was 9634, 6524 and 3908 kg (P) y(-1) from sod farms, citrus farms and row crop farmlands, respectively. Although the dairies represent less than 1% of the total area of Kissimmee basin, the simulated P load from the dairies (9283 kg (P) y(-1) in 2008) made up 5.4% of the total P load during 2008. On average, the modeled P yield rates from dairies, sod farms and row crop farmlands are 3.85, 2.01 and 0.86 kg (P) ha(-1) y(-1), respectively. The maximum sediment simulated phosphorus yield rate is about 2 kg (P) ha(-1) and the particulate simulated phosphorus contribution from urban, improved pastures and dairies to the total phosphorus load was estimated at 9%, 3.5%, and 1%, respectively. Land parcels with P oversaturated soil as well as the land parcels with high phosphorus assimilation and high total phosphorus contribution were located. The most critical sub-basin was identified for eventual targeting by enforced agricultural best management practices. Phosphorus load, including stream assimilation, incoming to Lake Okeechobee from two selected dairies was also determined.