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Current recommended nitrogen fertilization rates for St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] in South Florida range from 4 to 6 lb N per 1,000 ft2 per yr, applied throughout the year. Nevertheless, strict fertilizer ordinances are being passed by multiple counties in Florida, setting limits to the amount of N that can be applied to turfgrass areas, and establishing summer blackout periods for fertilizer applications; hence, there is a need to identify the minimum N rates to sustain St. Augustinegrass quality. A 4‐yr study was conducted at the University of Florida's Fort Lauderdale Research and Education Center to assess the turfgrass quality of four St. Augustinegrass cultivars ('CitraBlue', 'Floratam', 'Palmetto', and 'Raleigh') grown on a Hallandale fine sand (siliceous, isohyperthermic Lithic Psammaquents) and fertilized at either 2.5 or 5 lb per 1,000 ft2 per yr. Plots were evaluated monthly for visual turfgrass quality, and yearly for genetic color, leaf texture, spring green‐up, and summer density. CitraBlue had the highest turfgrass quality, color, and density. Differences were rarely detected among the other three cultivars. Nitrogen rates had an effect only on summer density, suggesting that St. Augustinegrass grown on Hallandale fine sand with 3.4% organic matter in South Florida could be managed with less N than is currently recommended without detrimental effects. Core Ideas: Over a 4‐yr period, 2.5 lb N per 1,000 ft2 per yr yielded adequate St. Augustinegrass quality.CitraBlue outperformed older cultivars in the trial.Minimal differences were detected among Floratam, Palmetto, and Raleigh.When soil organic matter is considerable, low N rates may provide sufficient lawn quality. [ABSTRACT FROM AUTHOR]

Turfgrass systems have been identified as potential sources of nitrate leaching and subsequent groundwater contamination. The HYDRUS (2D/3D) model was used to quantify nitrate leaching from bermudagrass [Cynodon dactylon (L.) Pers.] and buffalograss [Buchloe dactyloides (Nutt.) Engelm] established by either seed or sod and irrigated with either tailored (defined as reclaimed water with an N concentration of 15 mg L−1) or potable water and fertilized with calcium nitrate. A parameter sensitivity analysis conducted prior to model calibration revealed that soil texture, denitrification rate, and plant uptake all affected nitrate leaching. Simulated nitrate flux matched the experimental data more accurately when denitrification rate varied by soil depth. Moreover, nitrate leaching also differed between turfgrass species and between establishment methods. Leaching was higher from grasses propagated by seed than from sod at the beginning of the establishment period. Increasing the concentration of nitrate in tailored water from 0 to 200 mg L–1 increased concentrations at 50‐cm depths for both species but the increase was significantly higher under buffalograss than bermudagrass and was attributed to lower nutrient uptake and denitrification rates under buffalograss. Nitrate concentrations at 50‐cm depth were significantly higher for coarse sand compared with loamy sand, which was attributed to differences in retention times of the two soil types. Soil texture was even more important than nitrate application rate in predicting nitrate leaching losses and the results of the sensitivity analysis demonstrated that nitrate leaching was affected more by denitrification than by plant uptake. [ABSTRACT FROM AUTHOR]

The article discusses the Florida-friendly landscaping statute which may be applied in homeowner disputes involving an alleged violation of restrictive covenants. Topics explored include the required use of Saint Augustine grass for groundcover in some homeowners associations (HOA) restrictive covenants, the legislative intent and coverage of the statute, and the landscaping-related factors noted in the statute such as soil conditions, mulching, and yard waste recycling.

Pinoxaden is a herbicide inhibiting acetyl coenzyme A carboxylase recently introduced for use in turfgrass. Currently, pinoxaden is labeled for use in all bermudagrass [Cynodon dactylon (L.) Pers.] and zoysiagrass (Zoysia spp.) turfgrass areas except putting greens. However, pinoxaden is only labeled for use in St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] sod production because of injury concerns. Tank mixtures of two or more herbicides can reduce injury to turfgrass species. Injury reduction can also occur when fungicides are tank-mixed with herbicides. Research was conducted between 2018 and 2019 to determine the effect that pinoxaden alone and tank mixtures of pinoxaden with one of two common fungicides, chlorothalonil and propiconazole, would have on four different cultivars of St. Augustinegrass: 'Classic', 'Floratam', 'Palmetto', and 'Raleigh'. At the conclusion of the study, we determined that there is differential susceptibility to pinoxaden between cultivars of St. Augustinegrass and that both chlorothalonil and propiconazole have a safening effect on pinoxaden applications to StAugustinegrass, regardless of cultivar. The cultivars Classic and Raleigh were more susceptible to pinoxaden than Floratam and Palmetto. All four cultivars were less susceptible to pinoxaden when chlorothalonil and propiconazolewere applied in combination with pinoxaden. These results suggest that pinoxaden can be applied in a tank mixture with either chlorothalonil or propiconazole to reduce pinoxaden injury to St. Augustinegrass. However, the effect that these tank mixtures may have on weed control is currently unknown. [ABSTRACT FROM AUTHOR]

Core Ideas: Limited information is available concerning the effects of nitrogen (N) and golf cart traffic rates on buffalograss roughs.Increasing the N rate, especially from 0 to 1 or 1 to 2 lb N/1000 ft2/year, will increase the ability of buffalograss to better withstand traffic stress from golf carts in traffic situations.Increased late season percent green turfgrass cover and turfgrass quality were observed when applying 2 lb to 3 lb N/1000 ft2/year on buffalograss roughs.Buffalograss was able to maintain adequate green cover and acceptable quality with traffic rates up to 4 traffic passes/week. Buffalograss [Buchloë dactyloides (Nutt.) Engelm.] is increasing in popularity for use in golf course roughs in semiarid climates of the transitional climatic zone due to its low water requirements. Limited information is available concerning the effects of nitrogen (N) and golf cart traffic rates on buffalograss roughs. The objective of this study was to determine the influence of N rate and repeated simulated golf cart traffic on buffalograss maintained at golf course rough mowing height. Three field trials were initiated in July 2014 and 2015 in Manhattan, KS on 'Cody' buffalograss. Treatment factors were four N application rates (0, 1, 2, and 3 lb N/1000 ft2) and five traffic application rates (0, 2, 4, 8, and 16 passes/week) with a custom‐built golf cart traffic simulator. Regardless of traffic rate, as N rate increased, percent green cover (PGC), visual turf quality (VQ), and turf color increased. Results from this study indicate that an increase in N rate, especially from 0 to 1 lb N/1000 ft2/year and from 1 to 2 lb N/1000 ft2/year will increase the ability of buffalograss to better withstand traffic stress during the summer. Although, there may be minimal benefits of applying above 2 lb N/1000 ft2/year on buffalograss roughs. As traffic rate increased, regardless of N rate, buffalograss PGC, VQ, and turf color decreased, especially at 8 and 16 passes/week. Generally, buffalograss was able to maintain adequate PGC and acceptable VQ with traffic rates up to 4 traffic passes/week. We recommend that buffalograss turf managers carefully monitor traffic on buffalograss, especially in high traffic areas in the rough. Results show trafficked buffalograss can maintain adequate PGC and VQ when maintained at varying N levels. [ABSTRACT FROM AUTHOR]

Core Ideas: The fall is the optimum time to control winter annual and perennial broadleaf weeds.More information is needed on postemergence herbicide safety in the fall as buffalograss enters winter dormancy.Many postemergence herbicides can be safely applied to buffalograss entering winter dormancy with no effect on spring greenup.Turf managers have many herbicide and application timing options for weed control in buffalograss. [ABSTRACT FROM AUTHOR]

The use of warm season turfgrasses is a consolidated trend in the climatic transition zone of Mediterranean countries, in particular St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) begins to be widespread in warm coastal areas. However, little is known about the performance of the different cultivars of this species in southern Europe. In 2016-2017 a trial was carried out in three locations in Italy, Padova, Pisa, and Palermo, located in the north, center and south of the country respectively. Four cultivars (Floratine, Captiva, Sapphire, Palmetto) and five ecotypes (CeRTES 201, CeRTES 202, CeRTES 203, CeRTES 204, CeRTES 205) were compared in terms of their growth character-istics and morphological traits during establishment. The results highlighted that stolon growth was significantly affected by the location, as well as green colour retention. Stolon growth rate, internode length and internode volume and turf quality were, how-ever, significantly determined by the accession effect. The quality of the ecotypes was also in some cases comparable to that of the cultivars. In Padova, winterkill occurred in most of the accessions, while in Pisa and Palermo, all the entries survived. In conclusion, St. Augustinegrass is suitable for turf use in the central and south-ern coastal area of Italy. [ABSTRACT FROM AUTHOR]

St. Augustinegrass [Stenotaphrum secundatum (Walt) Kuntze] is an important turfgrass throughout many of the warm, humid regions of the world, including the southeastern United States. Unfortunately, the grass is susceptible to a number of insects, pathogens, and nematodes that adversely reduce its desirability as a turfgrass. Another Stenotaphrum species, pembagrass [S. dimidiatum (L.) Brongn.], offers a source of resistance to some of these pests. Crosses were made between pembagrass and St. Augustinegrass in an attempt to transfer desirable resistance genes into St. Augustinegrass. Two pembagrass accessions (PI 289729 and PI 365031) were used as the maternal parents, and different St. Augustinegrass cultivars and breeding lines were used as the paternal parents. Seed from these crosses were small, shriveled, lacking fully developed endosperm, and unable to germinate. A total of 218 embryos were cultured on a growth medium using embryo rescue techniques, and 127 seedlings were recovered. Paternal-specific expressed sequence tagsimple sequence repeat markers were used to identify the hybrids, and all 127 seedlings were determined to be F1 hybrids. These are the first reported hybrids between pembagrass and St. Augustinegrass. The crossability between the two species ranged from 0 to 67.1%, depending on the genotypes used, and the overall mean crossability was 30.8%. Crossability was greatly influenced by which pembagrass genotype was used as the maternal parent. This is an initial step toward introgressing desired genes for insect, nematode, and pathogen resistance from pembagrass into St. Augustinegrass. [ABSTRACT FROM AUTHOR]

Two diseases of St. Augustinegrass (SAG) [Stenotaphrum secundatum (Walt.). Ktze.] are caused by different anastomosis groups (AGs) of Rhizoctonia solani. Brown patch (BP) is a foliar disease of little economic importance, and large patch (LP) causes leaf sheath rot and death of affected turfgrass shoots and stolons. St. Augustinegrass genotypes were inoculated with an isolate that causes BP and an isolate that causes LP in repeated experiments. Three disease severity parameters were calculated from data recorded from each genotype, including final disease severity (Y), area under the disease progress curve (AUDPC), and the apparent infection rate (rL). The inoculation protocol reliably produced symptoms, and both rL and AUDPC provided statistically significant separations between genotypes for their susceptibility to BP and LP. A significant interaction between isolate and genotype was observed, and some genotypes that were very susceptible to LP were among the least susceptible to BP. These data suggest that differences in resistance to LP can be quantified in SAG genotypes, but genotype response may be isolate dependent. [ABSTRACT FROM AUTHOR]

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a widely used lawn grass in the southern United States due to its stoloniferous growth habit and shade tolerance. However, St. Augustinegrass is prone to thatch accumulation, which is conducive to pest problems, with the southern chinch bug (Blissus insularis Barber, SCB) being the most economically important one. Previous work to identify additional sources of SCB resistance reported genotypes with comparatively high numbers of recovered insects but low damage ratings. This study was conducted (i) to evaluate the performance of these materials in response to varying SCB feeding densities, and (ii) to determine feeding and oviposition under no-choice scenarios. Genotypes exposed to 0, 10, or 30 adult SCBs were evaluated after 4 wk for damage and insect survival. Significant differences were observed among genotypes. Across infestation levels, while recovered insect numbers for susceptible check 'Seville' and plant introductions 509038 and 509039 were not significantly different, damage ratings were significantly lower for the latter, indicating that these materials were tolerant to SCB feeding. In the no-choice experiments, survival levels of both males and females on week 4 were significantly lower for resistant check 'FX10', PI 365031, and PI 289729. These genotypes, along with PIs 291594, 300129, and 647924, showed significantly lower SCB oviposition and feeding compared with Seville. Our study was able to confirm that two PIs display tolerance to SCB feeding, and five additional PIs have antibiosis activity against adult SCB (likely antibiosis), representing sources of SCB resistance for future St. Augustinegrass breeding efforts. [ABSTRACT FROM AUTHOR]

St. augustinegrass (Stenotaphrum sp.) is a warm-season perennial turfgrass that grows widely in tropical regions around the world. St. augustinegrass is valued for both its turf performance and high levels of resistance to biotic and abiotic stresses. The current study was aimed at developing nuclear microsatellite markers for st. augustinegrass. Pyrosequencing of an enrichedmicrosatellite library on the Roche FLX platform using a 454 Titanium kit produced 57,306 sequence reads; 2614 of which contained short tandem repeats. One hundred primer pairs were tested with 18 accessions from the U.S. Department of AgricultureNational Plant GermplasmSystem st. augustinegrass collection grown in Griffin, GA. This collection contains both Stenotaphrum dimidiatum and Stenotaphrum secundatum accessions. Among revealed 100 primer pairs, 33 were polymorphic. A total of 175 alleles were amplified. The number of observed alleles per primer pair ranged from two to 10, with an average of 5.3. Shannon's information index and Nei's genetic diversity valueswere 0.4403 and 0.2873, respectively. This set of microsatellite markers is useful for assessment of genetic diversity and construction of molecular genetic linkage maps in st. augustinegrass. [ABSTRACT FROM AUTHOR]

Two full-season microplot experiments were conducted to evaluate the damage potential of a plant-parasitic nematode community on St. Augustine and centipede turfgrasses grown in three soil types and to assess the influence of soil type on reproduction of the nematode populations comprising the community. Genera of nematodes associated with both turfgrasses included Criconemella, Helicotylenchus, Meloidogyne, Pratylenchus, Tylenchorynchus, and Tylenchus spp. In 2012, nematodes did not cause significant damage to either turfgrass, but soil type affected plant growth parameters. In 2013, there was significant nematode-related injury to both turfgrasses, but there were no significant effects of soil type on plant growth parameters. [ABSTRACT FROM AUTHOR]

Buffalograss is a warm-season, dioecious grass species yielding burs, which are routinely used for field plantings. The pistillate plants bear the burs containing 1-5 caryopses. Isolated caryopses readily germinate, but caryopses contained within burs exhibit strong dormancy, suggesting that burs inhibit germination. Priming burs with low concentrations of potassium nitrate (KNO3) is used as an industry standard to improve germination. Seed dormancy and germination in many species are strongly influenced by endogenous hormone levels, principally abscisic acid (ABA) and gibberellic acid (GA). It follows that buffalograss seed dormancy might be induced or overcome by altering the ratio of ABA to GA. The objectives of this research were 1) to contrast the effects of priming with KNO3 or water on bur germination, 2) to study how these treatments affected hormone profiles, specifically the ABA/GA ratios in the burs, and 3) to quantify treatment effects on the water permeability of the burs. Hormone profiles were analyzed following four postharvest seed-soaking treatments (24-hour 0.05 M KNO3, 24-hour H2O, 48-hour 0.05 M KNO3, and 48-hour H2O). Water infiltration tests on nontreated, 24-hour H2O-treated, and 24-hour 0.05 M KNO3-treated seeds were also conducted. Inconclusive hormone profiling results did not support the hypothesis that KNO3 postharvest treatment raises GA levels to encourage germination. Instead, our data support changes in seed morphology following KNO3 postharvest seed treatments which alter water permeability of the seedcoat leading to increased germination. [ABSTRACT FROM AUTHOR]

Septic systems can be a potential source of phosphorus (P) in shallow groundwater. Our objective was to investigate the fate, mass balance, and transport of P in the drainfield of a drip-dispersal septic system. Drainfields were replicated in lysimeters (152.4 cm long, 91.4 cm wide, and 91.4 cm high). Leachate and effluent samples were collected over 67 events (n = 15 daily; n = 52 weekly flow-weighted) and analyzed for total P (TP), orthophosphate (PO 4 P), and other P (TP – PO 4 P). Mean TP was 15 mg L −1 (84% PO 4 P; 16% other P) in the effluent and 0.16 mg L −1 (47% PO 4 P, 53% other P) in the leachate. After one year, 46.8 g of TP was added with effluent and rainfall to each drainfield, of which, <1% leached, 3.8% was taken up by St. Augustine grass, leaving >95% in the drainfield. Effluent dispersal increased water extractable P (WEP) in the drainfield from <5 to >10 mg kg −1 . Using the P sorption maxima of sand (118 mg kg −1 ) and soil (260 mg kg −1 ), we estimated that ∼18% of the drainfield P sorption capacity was saturated after one year of effluent dispersal. We conclude that despite the low leaching potential of P dispersed with effluent in the first year of drainfield operation, a growing WEP pool in the drainfield and low P sorption capacity of Florida’s sandy soils may have the potential to transport P to shallow groundwater in long-running septic systems. [ABSTRACT FROM AUTHOR]

New elite st. augustinegrass cultivars with improved cold tolerance and desirable turf quality are needed for the turf industry, especially in the transitional climatic region of the United States. To efficiently use sources of cold tolerance in a breeding program, an understanding of the genetic control of this trait and its relationship to important turf quality traits is required. Therefore, the objective of this study was to estimate general and specific combining abilities for cold response and turf quality traits. Six diploid genotypes of st. augustinegrasswere selected as parents for a diallelmating design without reciprocals and evaluated over 3 years at two locations. The true hybridity of crosses was confirmed using simple sequence repeats (SSR). Combining ability analysis revealed that both general and specific combining abilities were significant across years and locations. Specific combining ability (SCA) was the largest source of genetic variation for winter survival, genetic color, turf density, and end-of-season cover indicating that nonadditive gene effects play a key role in the inheritance of these traits. The parental genotype 'GF2' was identified as a promising parent for future breeding efforts as it provided positive general combining ability (GCA) effects for both cold tolerance and turf quality traits, which were not significantly correlated with one another. Lines identified as parental selfs generally showed lower cold response and inferior turf quality than the original parental lines indicating that inbreeding depression can occur in st. augustinegrass. This study provides information regarding the combining ability of cold response and turf quality traits in st. augustinegrass, which will ultimately aid in parental selection for our future breeding efforts. [ABSTRACT FROM AUTHOR]

Buffalograss (Bouteloua dactyloides) is a low maintenance U. S. native turfgrass species with exceptional drought, heat, and cold tolerance. Leaf spot caused by Curvularia inaequalis negatively impacts buffalograss visual quality. Two leaf spot susceptible and two resistant buffalograss lines were challenged with C. inaequalis. Samples were collected from treated and untreated leaves when susceptible lines showed symptoms. Transcriptome sequencing was done and differentially expressed genes were identified. Approximately 27 million raw sequencing reads were produced per sample. More than 86% of the sequencing reads mapped to an existing buffalograss reference transcriptome. De novo assembly of unmapped reads was merged with the existing reference to produce a more complete transcriptome. There were 461 differentially expressed transcripts between the resistant and susceptible lines when challenged with the pathogen and 1552 in its absence. Previously characterized defense-related genes were identified among the differentially expressed transcripts. Twenty one resistant line transcripts were similar to genes regulating pattern triggered immunity and 20 transcripts were similar to genes regulating effector triggered immunity. There were also nine upregulated transcripts in resistance lines which showed potential to initiate systemic acquired resistance (SAR) and three transcripts encoding pathogenesis-related proteins which are downstream products of SAR. This is the first study characterizing changes in the buffalograss transcriptome when challenged with C. inaequalis. [ABSTRACT FROM AUTHOR]

Bermudagrass is a problematic weed in seashore paspalum and St. Augustinegrass with limited options for control. Ethofumesate is the only herbicide labeled for bermudagrass control in these turfgrasses, but the physiological basis for selectivity is not well understood. The objectives of this research were to evaluate the efficacy and fate of ethofumesate in bermudagrass, seashore paspalum, and St. Augustinegrass. In the greenhouse, ethofumesate rate that reduced shoot biomass 50% from the nontreated plants was 3.8, >27, and >27 kg a.i. ha-1 for bermudagrass, seashore paspalum, and St. Augustinegrass, respectively. In the laboratory, absorption of 14C-ethofumesate ranked bermudagrass > seashore paspalum > St. Augustinegrass from root uptake, and bermudagrass > seashore paspalum = St. Augustinegrass from foliar uptake. St. Augustinegrass translocated ~20% less of the total absorbed radioactivity to shoots than the other grasses after root uptake. Metabolism of 14C-ethofumesate ranked bermudagrass > St. Augustinegrass > seashore paspalum. All grasses metabolized the herbicide to ethofumesate-2-keto, methanesulfonic acid, and another polar metabolite. Of all grasses, seashore paspalum produced the highest and lowest levels of ethofumeaste-2-keto and methanesulfonic acid, respectively. Radioactivity recovery linearly decreased by 81 to 35% of the applied 14C, from 1 to 7 days after treatment, suggesting volatilization is a major contributor to ethofumesate losses. The susceptibility of bermudagrass to ethofumesate results from greater absorption than seashore paspalum and St. Augustinegrass. The intermediate tolerance of seashore paspalum to ethofumesate results from root absorption rather than foliar uptake. Metabolism rate does not appear to be correlated with tolerance levels of these species to ethofumesate. [ABSTRACT FROM AUTHOR]

The recommended N rates for St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze.) vary in Florida. This research, conducted in Fort Lauderdale, Citra, and Jay, FL, (20062008), aimed to determine the minimum N rate necessary for acceptable St. Augustinegrass and to determine the influence of N and irrigation rate on NO3-N leaching. Urea was applied in Fort Lauderdale, Citra, and Jay at 98, 196, 294, and 588; 49, 196, 343, and 490; and 49, 98, 196, and 294 kg N ha-1 yr-1, respectively, based on best management practices. Irrigation was 2.5 mm d-1 and 13.0 mm three times weekly in Fort Lauderdale; 13 mm twice weekly and 26 mm wk-1 in Citra and Jay. In Fort Lauderdale and Jay, lower than recommended N rates mostly produced acceptable turfgrass. Applications of 196 kg N ha-1 (Fort Lauderdale) and 98 kg N ha-1 (Jay) were the lowest rates producing acceptable turf. In Citra, 65% more N was required for acceptable turf than the recommended minimum . Leaching from all N rates was similar, except when N rates exceeded recommendations or when turfgrass exhibited herbicide stress. The high irrigation rate doubled NO3-N leaching compared to the low rate in Fort Lauderdale; irrigation frequency had no influence on leaching in Citra or Jay. The predicted minimum N rate for acceptable turf in Fort Lauderdale was <98 kg N ha-1 yr-1 (lower than in Citra; more than in Jay). In stressed turf, additional N conferred little benefit to quality and increased leaching. [ABSTRACT FROM AUTHOR]

Core Ideas: Turf managers may be hesitant to embrace buffalograss due to its slow germination and establishment rate.Lowering the mowing height will have minimal impact on buffalograss establishment.Slit seeding resulted in the quickest conversion from tall fescue to buffalograss.If slit seeding is not possible, core aerating or verticutting will hasten buffalograss establishment compared with not cultivating at all. [ABSTRACT FROM AUTHOR]

Core Ideas: Many postemergence herbicides can be safely applied during buffalograss greenup in early to mid‐April (0% greenup) with little chance of turf damage.Herbicide that does not contain 2,4‐D can be safely applied during buffalograss greenup until 1 June (70‐85% greenup).Herbicide containing 2,4‐D should be applied before the first week of May (10‐15% greenup) for turf safety concerns, or apply no later than third week of May (50‐60% greenup) for acceptable stand during the summer months. [ABSTRACT FROM AUTHOR]

Understanding rooting dynamics using the minirhizotron technique is useful for cultivar selection and to quantify nematode damage to roots. A 2-yr microplot study including five bermudagrass ('Tifway', Belonolaimus longicaudatus susceptible; two commercial cultivars [TifSport and Celebration] and two genotypes ['BA132' and 'PI 291590'], which have been reported to be tolerant to B. longicaudatus) and two St. Augustinegrass ('FX 313', susceptible, and 'Floratam' that was reported as tolerant to B. longicaudatus) genotypes in a 5 x 2 and 2 x 2 factorial design with four replications, respectively, was initiated in 2012. Two treatments included were uninoculated and B. longicaudatus inoculated. In situ root images were captured each month using a minirhizotron camera system from April to September of 2013 and 2014. Mixed models analysis and comparison of least squares means indicated significant differences in root parameters studied across the genotypes and soil depths of both grass species. 'Celebration', 'TifSport' and 'PI 291590' bermudagrass, and 'Floratam' St. Augustinegrass had significantly different root parameters compared to the corresponding susceptible genotypes (P ≤ 0.05). Only 'TifSport' had no significant root loss when infested with B. longicaudatus compared to non-infested. 'Celebration' and 'PI 291590' had significant root loss but retained significantly greater root densities than ' Tifway' in B. longicaudatus-infested conditions (P ≤ 0.05). Root lengths were greater at the 0 to 5 cm depth followed by 5 to 10 and 10 to 15 cm of vertical soil depth for both grass species (P≤ 0.05). 'Celebration', 'TifSport', and 'PI 291590' had better root vigor against B. longicaudatus compared to Tifway. [ABSTRACT FROM AUTHOR]

The western chinch bug, Blissus occiduus Barber, is a serious pest of buffalograss, Buchloe dactyloides (Nuttall) due to physical and chemical damage caused during the feeding process. Although previous work has investigated the feeding behaviors of chinch bugs in the Blissus complex, no study to date has explored salivary gland morphology and the associated salivary complex of this insect. Whole and sectioned B. occiduus salivary glands were visualized using light and scanning electron microscopy to determine overall structure and cell types of the salivary glands and their individual lobes. Microscopy revealed a pair of trilobed principal glands and a pair of tubular accessory glands of differing cellular types. To link structure with function, the salivary gland proteome was characterized using liquid chromatography tandem mass spectrometry. The salivary proteome analysis resulted in B. occiduus sequences matching 228 nonhomologous protein sequences of the pea aphid, Acyrthosiphon pisum (Harris), with many specific to the proteins present in the salivary proteome of A. pisum. A number of sequences were assigned the molecular function of hydrolase and oxido-reductase activity, with one specific protein sequence revealing a peroxidase-like function. This is the first study to characterize the salivary proteome of B. occiduus and the first of any species in the family Blissidae. [ABSTRACT FROM AUTHOR]

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a warm season turfgrass and is widely used for lawns and landscapes in the southern United States of America. The southern chinch bug (Blissusinsularis Barber) is the most damaging insect of St. Augustinegrass. Use of resistant cultivars is an environmentally sound and sustainable method to control this insect pest. Two newly identified resistant St. Augustinegrass lines (NUF3231 and NUF4872) were compared with three commercial cultivars for turfgrass quality and other important traits. The two lines had turf color and turf visual quality similar to those of Captiva and similar to or better than those of Floratam and Palmetto during the experiment. NUF4872 had higher level of resistance to gray leaf spot than Floratam and Palmetto. Stolon architectures of NUF3231 were similar to those of Captiva whereas NUF4872 had the stolons similar to those of Floratam. The results indicated that the two lines could potentially be released as commercial cultivars for use on lawns to battle against the southern chinch bug. [ABSTRACT FROM PUBLISHER]

Concern exists over the potential loss of nitrogen (N) and phosphorus (P) in runoff from newly established and fertilized lawns. Nutrient losses can be higher from turf when shoot density and surface cover are low and root systems are not fully developed. This study was conducted to evaluate fertilizer source and timing effects on nutrient losses from newly sodded lawns of St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze]. For each study, 12 33.6-m² plots were established on an undisturbed Alfisol having a 3.7% slope. Each plot was equipped with a runoff collection system, instrumentation for runoff flow rate measurement, and automated samplers. A 28-d establishment study was initiated on 8 Aug. 2012 and repeated on 9 Sept. 2012. Treatments included unfertilized plots, fertilized plots receiving 4.88 g N m-2 as urea 6 d after planting, fertilized plots receiving 4.88 g N m-2 as sulfur-coated urea 6 d after planting, and fertilized plots receiving 4.88 g N m-2 as urea 19 d after planting. Runoff events were created by irrigating with 17 mm of water over 27 min. Runoff water samples were collected after every 37.8 L and analyzed for NO3-N, NH4-N, dissolved organic N (DON), and PO4-P. Increases of approximately 2 to 4 mg L-1 NO3-N and 8 to 12 mg L-1 PO4-P occurred in runoff 1 d after fertilization, which returned to background levels within 7 d. Total fertilizer N lost to runoff was 0.6 to 4.2% of that applied. Delaying fertilizer application until 19 d after planting provided no reduction in nutrient loss compared with a similar application 6 d after planting. Approximately 33% of the N lost in runoff was as DON. This large amount of DON suggests significant N loss from decomposing organic matter may occur during sod establishment. [ABSTRACT FROM AUTHOR]

Understanding plant resistance mechanisms at a molecular level would provide valuable insights into the biological pathways impacted by insect feeding, and help explain specific plant tolerance mechanisms. As a first step in this process, we conducted next-generation sequencing using RNA extracted from chinch bug-tolerant and -susceptible buffalograss genotypes at 7 and 14 d after chinch bug feeding. Sequence descriptions and gene ontology terms were assigned to 1,701 differentially expressed genes. Defense-related transcripts were differentially expressed within the chinch bug-tolerant buffalograss, Prestige, and susceptible buffalograss, 378. Interestingly, four peroxidase transcripts had higher basal expression in tolerant control plants compared with susceptible control plants. Defense-related transcripts, including two peroxidase genes, two catalase genes, several cytochrome P450 transcripts, a glutathione s-transferase, and a WRKY gene were upregulated within the Prestige transcriptome in response to chinch bug feeding. The majority of observed transcripts with oxidoreductase activity, including nine peroxidase genes and a catalase gene, were downregulated in 378 in response to initial chinch bug feeding. The observed difference in transcript expression between these two buffalograss genotypes provides insight into the mechanism(s) of resistance, specifically buffalograss tolerance to chinch bug feeding. [ABSTRACT FROM AUTHOR]

Turf fertilization in Florida continues to be viewed as contributing to nonpoint-source pollution of ground water. Continued research is needed to validate existing best management practices (BMPs). The objectives of this research were to evaluate nitrate-N (NO3-N) leaching, turf quality, and turf growth rate from N sources applied to 'Floratam' St. Augustine grass [Stenotaphrum secundatum (Walter) Kuntze] and common centipede grass [Eremochloa ophiuroides (Munro) Hack.]. Research was conducted in Jay, FL, from 2008 to 2011. Nitrogen was applied in 60-d cycles at 48 kg ha-1 as ammonium nitrate, urea, 30% slow-release N (SRN), 50% SRN, polymer- coated urea (PCU), and biosolid (BS) and in 120-d cycles at 98 kg ha-1 as PCU. Nitrogen leaching was greatest during the first 6 mo following turf sodding for both species with 21.6 and 10.1 kg ha-1 leached from St. Augustinegrass and centipedegrass, respectively. Following sodding, no differences in N leached between turfgrasses were observed until 2010 when winterkill and large patch (Rhizoctonia solani Kühn) were observed on St. Augustinegrass. Turf quality of control plots was above acceptable levels in 2008 but was unacceptable by 2011. Each N source produced acceptable centipedegrass with few differences among N sources. A blend of 50% ammonium sulfate and 50% PCU resulted in higher growth rates and turf quality of St. Augustinegrass than other N sources in most years. Recommending N applications to newly sodded turf may not be necessary due to the risk of leaching during establishment. [ABSTRACT FROM AUTHOR]

Rock colonization by plant roots and their associated microbiota is one of the major drivers of mineral weathering, nutrient cycling, soil formation and ecosystem stability. Yet the mechanisms of bio-uptake of lithogenic elements from rocks with differential nutrient availabilities and limitations are yet to be established. Here we present results from a mesocosm experiment that examined lithogenic element dissolution and uptake (P, K, Ca, Mg, Mn, Fe, Na, Ti, Al and Si) in Bouteloua dactyloides (buffalo grass) grown on four different granular porous media (basalt, rhyolite, granite and schist) comprised of primary mineral assemblages as influenced by arbuscular mycorrhiza (AM; Rhizophagus irregularis). Our results demonstrated that nutrient mobilization (chemical denudation + plant uptake) in such oligotrophic systems is governed by nutrient supply in the parent material, nutrient availability in pore water solution, and plant physiology. Overall, total major lithogenic element mobilization in planted columns (with and without AM) exceeded abiotic controls in all substrates. Differences in total mobilization among substrates occurred as follows: Fe, Na, Ti and Al reached high values in planted treatments in basalt, P and Mn in rhyolite, Ca and K in granite and K in schist, suggesting enhanced dissolution of primary minerals in the presence of plants. Element biomass enrichment of Mn, Fe, Ti and Al appeared to be higher in basalt than the rest of the substrates; however, high Al availability limited Ca and Mg uptake and plant growth in this rock media. Presence of mycorrhiza enhanced shoot biomass in rhyolite due to increased P uptake, and increased concentrations and total uptake of lithogenic elements in plants in all rocks but granite. As expected, AM significantly increased plant root concentrations of P, K, Ca, Mn, Fe, Ti, Al in basalt, and Mn shoot concentrations in rhyolite, as well as root total uptake of K, Ca, Mg, Mn, Fe, Na, Ti, Al and Si in basalt. At the same time, AM decreased Ca, Ti and Al concentrations in shoots grown in rhyolite, a possible protection mechanism against Al toxicity. The importance of AM in nutrient uptake is also reinforced by positive correlations between AM infection rate and P, Ca and Mn total uptake across all substrates. Moreover, total mobilization of Ca, Mg and Mn in rhyolite, was significantly higher in the AM versus non-AM treatment, contrary to K, Ca, Mg, Na and Si in schist. Our work demonstrates how mineral weathering and associated nutrient release is promoted by plant processes, further enhanced by plant associated with symbiotic AM, and yet more pronounced in basalt and rhyolite compared to granite and schist. [ABSTRACT FROM AUTHOR]

Tropical sod webworm, Herpetogramma phaeopteralis Guenée, is an important pest of warm-season turfgrass in the Gulf Coast states of the United States, the Caribbean Islands, and Central America. Current control recommendations rely on topical application of insecticides against caterpillars. The objective of this study was to generate resistance baseline data of H. phaeopteralis to six insecticide classes. Residual activity of clothianidin, chlorantraniliprole, and bifenthrin was also compared under field conditions in Central Florida. Chlorantraniliprole was the most toxic compound tested (LC50 value of 4.5 ppm), followed by acephate (8.6 ppm), spinosad (31.1 ppm), clothianidin (46.6 ppm), bifenthrin (283 ppm) and Bacillus thuringiensis kurstaki, (342 ppm). In field tests, all compounds at label rates were effective (≥94% mortality of larvae exposed to fresh residues). However, a more rapid decline in activity of clothianidin and bifenthrin was observed compared with chlorantraniliprole. Clothianidin had no statistically detectable activity after 4 wk post-application in spring and the fall, and bifenthrin had no detectable activity after 3wk in the spring and the fall. However, chlorantraniliprole maintained significant activity (≥84% mortality) compared with other treatments throughout the 5-wk study period. This study provides new information regarding the relative toxicities and persistence of current insecticides used for H. phaeopteralis and other turfgrass caterpillars. [ABSTRACT FROM AUTHOR]

Southern chinch bug, Blissus insularis Barber, is a severe pest of St. Augustinegrass throughout the southern United States. Host plant resistance is an environmentally friendly method to manage chinch bug infestations and is increasingly important, as the southern chinch bug develops resistance to insecticides. In this study, in an effort to understand resistance mechanisms in two varieties of St. Augustinegrass ('FX-10' and 'NUF-76'), we used the electrical penetration graph method to quantify stylet probing behaviors in two resistant and two susceptible St. Augustinegrass varieties. Overall, chinch bugs spent less time probing on resistant FX-10 and NUF-76 than on susceptible 'Floratam' and 'Palmetto', and individual probes were shorter in average duration but more numerous in resistant varieties than in susceptible varieties. During probing, chinch bugs spent more time in pathway-associated stylet activities (i.e., penetration through epidermal and mesophyll tissue) in the resistant varieties than in the susceptible varieties, likely indicating difficulty in finding and accessing an ingestion site. As a consequence, chinch bugs spent proportionately much less time engaged in xylem ingestion in both resistant varieties than in susceptible varieties but only in FX-10 were phloem-associated activities significantly reduced compared with those in susceptible varieties. We conclude that there is evidence for non-phloem-associated chinch-bug resistance factors in both NUF-76 and FX-10, and phloem-associated factors in FX-10. [ABSTRACT FROM AUTHOR]

Alien plant invasion and nutrient enrichment as a result of anthropogenic landscape modification seriously threaten native plant community diversity. It is poorly understood, however, whether these two disturbances interact with the functional identity of recipient native plants to drive community change. We performed a mesocosm experiment to examine whether the interactive effects of invasion by a stoloniferous turf-grass Stenotaphrum secundatum and nutrient enrichment vary across different plant growth forms of an endangered coastal plant community. Communities contained 18 species (drawn without replacement from a pool of 31 species) with either runner, tufted or woody growth forms. Species were well-established and reproductively mature prior to S. secundatum introduction. Species growth (% cover), reproductive output, soil temperature and light availability were monitored for two growing seasons. Invasion and nutrient enrichment (two levels: 'natural control' and 'enriched') had no effect on species richness, community composition, reproductive output, soil temperature or light penetration. There was no interactive effect of nutrients and invasion on community productivity (i.e. final biomass), such that invasion caused a reduction in community biomass at both natural and enriched nutrient levels. This was driven only by reduced biomass of functionally-similar native runner species, which share similar root morphologies and nutrient-acquisition strategies with S. secundatum. Our study indicates that impacts of invasion are dependent upon the functional identity of species within recipient communities, not the availability of resources. This shows that management cannot buffer invader effects by manipulating resource availability. Revegetation strategies should target functionally-similar natives for replacement following invader control. [ABSTRACT FROM AUTHOR]

In Florida, St. Augustinegrass (Stenotaphrum secundatum) is the most commonly used turfgrass species. Sting nematode (Belonolaimus longicaudatus) is recognized as a limiting factor to St. Augustinegrass in Florida, where 'Floratam', a polyploid, is the predominant cultivar; although the use of new diploid cultivars is increasing. The objective of this study was to evaluate the root response of three cultivars, Floratam, and two diploid cultivars 'Palmetto' and 'Captiva' grown in plastic pots containing 650 cm³ of sand in a greenhouse to inoculation with 0, 50, or 300 B. longicaudatus/pot. Ninety days after inoculation, nematodes were extracted from the complete soil volume of the pots and counted. Roots were washed clean of soil, scanned, and root lengths, mean root diameters, and mean root volume were measured. All cultivars were good hosts for B. longicaudatus, 'Palmetto' supported higher population densities than the other cultivars at the 50 nematode inoculation rate only. There were differences in reproductive factor (Rf) among the inoculation rates, where the 50 nematode inoculation rate (Pi) had an Rf of 0.52, and the 300 nematode inoculation rate had an Rf of 1.84. At Pi 300, the non-infested treatment had greater root lengths than inoculated for all cultivars, demonstrating that B. longicaudatus has a significant effect on St. Augustinegrass root development. Root diameter and volume were not affected by inoculation with B. longicaudatus. Root diameter and volume were higher for Floratam than for Palmetto or Captiva. Palmetto had greater root length than the other cultivars. [ABSTRACT FROM AUTHOR]

Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) is a sensitive technique for normalization of the gene expression level of target genes. Buffalograss (Buchloe dactyloides), a warm-season turfgrass with strong abiotic stress resistance, is widely used in North China. Up to now, no work was performed to evaluate the reference genes in buffalograss. In this study, the expression profiles of ten potential reference genes were examined by qRT-PCR in 24 buffalograss samples, which were subjected to a different treatment (salt, osmotic, cold and heat). Three qRT-PCR analysis methods (GeNorm, NormFinder, and Bestkeeper) were used to evaluate the stability of gene expression. The results indicated that DNAJ and β-ACTIN were the optimal reference genes for salt-treated leaves, and the combination of PP2A and GAPDH was better reference genes for PEG-treated leaves. Under cold stress, DNAJ and β-ACTIN showed less variety of expression level in leaves. DNAJ and GAPDH exhibited the most stable expression in heat-treated samples. To sum up, glyceral-dehyde-3-phosphate dehydrogenase (GAPDH), β-ACTIN, DNAJ-like protein (DNAJ) and protein phosphatase 2A (PP2A) were selected as the most stable reference gene among all tested samples. To further validate the suitability of these reference genes, the expression levels of DREB2 (homologs of AtDREB2) were analyzed in parallel. Our results show that the best reference genes differed across different experimental conditions, and these results should enable better normalization and quantification of transcript levels in buffalograss in the future. [ABSTRACT FROM AUTHOR]

St. Augustinegrass ( Stenotaphrum secundatum (Walter) Kuntze) is an economically important turfgrass in the southeastern United States. However, this turf species is prone to southern chinch bug, Blissus insularis Barber (Heteroptera: Blissidae) outbreaks. This insect is the most destructive pest of St. Augustinegrass wherever this turfgrass is grown. Host plant resistance has historically been an effective management tool for southern chinch bug. Since 1973, the 'Floratam' St. Augustinegrass cultivar effectively controlled southern chinch bug in the southeast. However, southern chinch bug populations from Florida and Texas have now circumvented this resistance, through mechanisms still unknown. Therefore, identifying and deployingnewcultivars with resistance to the southern chinch bug is imperative to combat this pest in an economically and environmentally sustainable manner. Currently, the number of cultivars with resistance against southern chinch bug is limited, and their efficacy, climatic adaptability, and aesthetic characters are variable. Hence, the main focus of this study is the identification of alternative sources of resistance to southern chinch bugs in previously uncharacterized St. Augustinegrass plant introductions (PIs) and its closely related, crossbreeding species, Pembagrass ( Stenotaphrum dimidiatum (L.) Brongniart). The PIs exhibited a wide range of responses to southern chinch bug feeding, as indicated by damage ratings. Damage ratings for seven PIs grouped with our resistant reference cultivars. Moreover, nine PIs exhibited antibiosis, based on poor development of southern chinch bug neonates, when compared with our susceptible reference cultivars. Altogether our study has produced strong support to indicate these materials are good candidates for future southern chinch bug resistance breeding in St. Augustinegrass. [ABSTRACT FROM AUTHOR]

Invasive plants significantly threaten native plant biodiversity, yet the mechanisms by which they drive species losses and maintain their own dominance are poorly known. We examined the effects of alien grass invasion ( Stenotaphrum secundatum) on (1) abundance and frequency of occurrence, (2) reproductive effort (flowering) and output (fruit production) and (3) soil seed banks for three focal native plants that are characteristic of endangered coastal forest of south-eastern Australia. First, we sampled and compared the foliage cover abundance and frequency (proportion of sites occupied) of the focal natives across invaded and non-invaded (reference) sites ( n = 20). We then intensively sampled reproductive effort and output (range of 5-9 sites per species), and density of propagules within the soil (using a standard glasshouse 'emergence' method; n = 26) for each species. Invasion was associated with reduced population sizes of all species within the standing vegetation but did not affect population frequency (i.e. proportion of sites where each species was present). Reproductive effort and output were about 75 % lower at invaded than native sites for all species. However, invasion had no effect on propagule densities of the focal natives within the seed bank, despite the substantial reduction in their reproduction. This indicates that the ultimate driver of population declines across invaded landscapes is post-settlement recruitment limitation from the seed bank (e.g. low rates of germination and seedling survival) rather than a reduction in the arrival and storage of propagules at invaded sites. Removal of Stenotaphrum alone might thus be sufficient to stimulate the recovery of native populations from the seed bank. [ABSTRACT FROM AUTHOR]

Abstract: Dehydration responsive element binding (DREB) transcription factors play an important role in the regulation of stress-related genes. These factors contribute to resistance to different abiotic stresses. In the present study, a novel DREB transcription factor, BdDREB2, isolated from Buchloe dactyloides, was cloned and characterized. The BdDREB2 protein was estimated to have a molecular weight of 28.36kDa, a pI of 5.53 and a typical AP2/ERF domain. The expression of BdDREB2 was involved in responses to drought and salt stresses. Overexpression of BdDREB2 in tobacco showed higher relative water and proline content, and was associated with lower MDA content under drought stress, suggesting that the transgenic tobacco may tolerate drought stress better. Results demonstrate that BdDREB2 may play an important role in the regulation of abiotic stress responses, and mediate many physiological pathways that enhance stress tolerance in plants. [Copyright &y& Elsevier]

Illumina sequencing data was used to develop simple sequence repeat (SSR) markers for St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze], an economically important warm-season turfgrass. Polymorphism was observed in 190 of 215 designed SSR markers among a panel of eight diverse germplasm accessions. Of these, 94 were subsequently used to assess levels of diversity within a diverse collection of S. secundatum and pembagrass [Stenotaphrum dimidiatum (L.) Brongn.] germplasm. A total of 982 alleles ranging in size from 63 to 250 bp were amplified. Levels of polymorphism were high, with number of alleles amplified per loci ranging from 5 to 23 (μ = 10) and with polymorphic information content values ranging from 0.09 to 0.83 (μ = 0.54). Cluster and principal coordinate analyses of S. secundatum and S. dimidiatum accessions showed groupings based primarily on ploidy level. Analysis of population structure identified six subpopulations with some admixture present among them. Additionally, the ability of these newly developed SSR markers to uniquely identify specific cultivars was assessed. A set of five SSR markers were capable of producing unique banding patterns for all but two cultivars. These markers, the first developed for the species, should be useful for linkage mapping, diversity and pedigree analyses, accurate varietal identification, and marker-assisted selection in St. Augustinegrass. [ABSTRACT FROM AUTHOR]

False smut caused by Cercospora seminalis is an important disease of buffalograss (Buchloë dactyloides) affecting seed production. The pathogen prevents normal caryopsis development and causes considerable yield loss and reduced seed germination. The current taxonomic placement of the falsesmut causal pathogen in the genus Cercospora is incorrect based on its morphological characteristics and DNA phylogeny. In the present study the phylogenetic position of C. seminalis is clarified based on DNA sequence analysis of three loci namely the internal transcribed spacer (ITS) region, partial nuclear ribosomal large subunit (LSU) and partial sequences of the RNA polymerase II second largest subunit (RPB2). A collection of C. seminalis isolates was made from buffalograss sites near Lincoln, Nebraska. DNA sequence data indicated that Cercospora seminalis is phylogenetically close to but distinct from species of Bipolaris and Curvularia (Pleosporaceae, Pleosporales). Cercospora seminalis morphologically had unique characteristics, namely densely aggregated and repeatedly branched conidiophores arising from a brown stroma, monotretic conidiogenous cells with inconspicuous loci, and scolecosporous conidia with distosepta, and thickened, darkened hila. Porocercospora is introduced as a new genus to accommodate the buffalograss false-smut pathogen. [ABSTRACT FROM AUTHOR]

This study shows the structural characterization of silica particles extracted from Stenotaphrum secundatum (St. Augustine) grass using an annelid-based biotransformation process. This bioprocess starts when St. Augustine grass is turned into humus by vermicompost, and then goes through calcination and acid treatment to obtain silica particles. To determine the effect of the bioprocess, silica particles without biotransformation were extracted directly from the sample of grass. The characterization of the silica particles was performed using Infrared (FTIR) and Raman spectroscopy, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Dynamic Light Scattering (DLS), and Energy Dispersion Spectroscopy (EDS). Both types of particles showed differences in morphology and size. The particles without biotransformation were essentially amorphous while those obtained via annelids showed specific crystalline phases. The biological relationship between the metabolisms of worms and microorganisms and the organic-mineral matter causes changes to the particles' properties. The results of this study are important because they will allow synthesis of silica in cheaper and more ecofriendly ways. [ABSTRACT FROM AUTHOR]

There are increasing concerns about the fate of fertilizers applied to lawn grasses. The objectives of this research were to evaluate nitrate leaching and turf response to nitrogen (N) treatment and irrigation in newly sodded St. Augustinegrass. The research was conducted in Citra, FL in 2006 and 2007. Nitrogen was applied at three rates day of sodding and again at 30 days after planting. Analysis of variance indicated there were no differences in nitrate-N (NO3–N) leached due to N treatment or timing. During the establishment period, NO3–N loading was greater than reported for established turf and could possibly present a source of nitrate contamination. Turf quality and color were above or just below an acceptable score at all N rates. Due to the potential for high amounts of NO3–N leaching in new sod, it is not recommended to apply N fertilizer to St. Augustinegrass in the first 30–60 days after planting. [ABSTRACT FROM PUBLISHER]

St. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is considered to be one of the most shade-tolerant warm-season turfgrasses, yet information is lacking on intraspecies developmental responses and performance in shade. This greenhouse study was conducted to 1) compare quality, development, and physiological responses of 10 commercial and experimental lines of st. augustinegrass in moderate and heavy [32% and 15% photosynthetic photon flux (PPF), respectively] shade environments' and 2) evaluate physiological and morphological indicators that could be used in rapid screening for shade tolerance among st. augustinegrass progeny from a segregating population. A range of shade tolerance was observed between the entries, as noted by quality and percent green cover after 10 weeks of imposed shade conditions. In moderate shade, most entries maintained acceptable (6 or greater) quality and greater than 50% green cover. However, in heavy shade, only 'Captiva', 'Amerishade', and 'PI 600734' maintained acceptable quality, with only PI 600734 and Captiva maintaining greater than 50% cover. 'TAES 5732-6', an embryo rescue-derived hybrid from 'Floratam', exhibited the least shade tolerance of the group in both shade environments. Neither chlorophyll content nor total nonstructural carbohydrates related well to observed shade quality differences between the entries. A strong correlation existed between shoot elongation rate of a cultivar and its corresponding final percent green cover in moderate shade (R² = 0.66) but not in heavy shade (R² = 0.19), suggesting that moderate shade may be the better environment for discriminating genetic differences among st. augustinegrass germplasm for shade tolerance. [ABSTRACT FROM AUTHOR]

As a result of increasing demand for potable water, local and national initiatives to conserve municipal water supplies have been implemented. Many of these initiatives focus on reducing irrigation of turfgrass in urban landscapes and may totally ban irrigation during periods of severe water shortage. Proper selection of adapted turfgrass species and cultivars is vital to long-term water conservation initiatives. Turfgrasses that can survive and recover from extended hot and dry periods under limited to no irrigation would best meet water conservation objectives. The present study was conducted to evaluate the recuperative potential of transplanted plugs of 24 commonly grown cultivars of three warm-season turfgrass species after incremental increases in water stress imposed by withholding all water for up to 60 days. A 2-year field study was conducted consisting of eight blocks containing 25 plots each. Each block was planted with one plot each of eight cultivars of bermudagrass (Cynodon dactylon sp.), seven cultivars of st. augustinegrass (Stenotaphrum secundatum sp.), and nine cultivars of zoysiagrass (five of Zoysia japonica sp. and four of Zoysia matrella sp.). Four blocks were planted on native soil with no restriction to rooting, whereas the other four had an effective root zone of only 10 cm of soil. Cup cutter plugs were collected at predetermined intervals, transported to College Station, TX, replanted, and grown under well-watered conditions. Measurements of the lateral spread of the plugs were taken every 10 to 14 days for the first 60 to 70 days after planting (DAP). The lateral spread of plugs collected after 0 days of summer dry-down (DSD) was greatest for bermudagrass, intermediate for St. augustinegrass, and lowest for zoysiagrass. In most cases there were no consistent differences between cultivars within a species. All species grown on the 10-cm deep root zone were unable to survive the 60-day period without water and died within the first 40 days. For each species, lateral spread was increasingly delayed or reduced with increasing DSD. Although all three species grown on native soil were able to survive and recover from a 60-day period without water, the bermudagrass cultivars had the most rapid recovery rates measured as lateral spread of transplanted plugs. [ABSTRACT FROM AUTHOR]

Clonal plants could modify phenotypic responses to nutrients heterogeneously distributed both in space and time by physiological integration. It will take times to do phenotypic responses to modifications which are various in different growth periods. An optimal phenotype is reached when there is a match between nutrient conditions and foraging ability. A single plantlet of Buchloe dactyloides with two stolons was transplanted into heterogeneous nutrient conditions. One stolon grew in homogeneous nutrient patch, while the other cultured in different scales of heterogeneous nutrient patches. As compared to the other nutrient treatment, heterogeneous nutrient treatments with small scale of 25×25 cm resulted in a higher biomass, and larger number of ramets, clumps and stolons in B. dactyloides at both genet and clonal fragment levels. Significant differences of number of ramets, clumps and stolons were detected at the rapid growth stage, but not in the early stage of the experiment. Foraging ability was more efficient in heterogeneous than in homogeneous nutrient conditions as assessed by higher root mass and root to shoot ratio. Different nutrient treatments did not prompt significant differences in internode and root length. Physiological integration significantly increased biomass, but did not influence other growth or morphological characters. These results suggest that physiological integration modifies phenotypic plasticity of B. dactyloides for efficient foraging of nutrients in heterogeneous nutrient conditions. These effects are more pronounced at genet and clonal fragment levels when the patch scale is 25×25 cm. Time is a key factor when phenotypic plasticity of B. dactyloides in heterogeneous nutrient conditions is examined. [ABSTRACT FROM AUTHOR]

Determination of total nonstructural carbohydrate levels in turf-type buffalograss [Buchloë dactyloides (Nutt.) Engelm.] genotypes as influenced by mowing height has not been previously investigated. The objectives of this study were to determine the influence of buffalograss genotype and mowing height on total nonstructural sugar and starch content during the growing season. The study was conducted at the John Seaton Anderson Turfgrass Research Facility located near Mead, NE. Cultivars Legacy and Prestige along with selections NE-2979 and NE-2964 from the buffalograss breeding program at the University of Nebraska were studied. The genotypes were mowed at 1.6 and 5.0 cm. Sugar and starch content trends were similar, but differences in carbohydrate concentration among genotypes were observed. NE-2964 exhibited the greatest sugar content, 6.37% at 5-cm mowing height, and NE-2979 the lowest sugar content, 1.75% at 5-cm mowing height. Legacy exhibited the greatest starch content, 12.6% at 5-cm mowing height, and NE-2979 the lowest starch content, 1.3% at 5-cm mowing height. Surprisingly, mowing height had little effect on sugar or starch levels of buffalograss. Genotype was the greatest source of variation for sugar and starch content, indicating that different genotypes partition or allocate carbohydrates differently. These results show the seasonal carbohydrate content variations among buffalograss genotypes and provide some insight as to why those changes occur. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is required to maintain healthy, high-quality, warm-season turf. However, excessive P applications to soils with poor P retention capabilities may lead to leaching losses to groundwater. This field study was conducted to determine the maximum P fertilizer application rate to Stenotaphrum secundatum (Walt.) [Kuntze] 'Floratam' St. Augustinegrass (St. Augustinegrass) and Zoysia japonica 'Empire' zoysiagrass (zoysiagrass) below which P leaching is minimized. Five P levels ranging from 0 to 5.0 g P m-2 yr-1 were surface applied as triple superphosphate. Turf was established on an uncoated, low-P sand with negligible P retention capacity. Leaf and root growth, tissue P concentration, soil P concentration, soil P saturation, leachate volume, and orthophosphate (Pi) concentration in leachates were measured. Mehlich 1--extractable soil P (M1-P) and soil P saturation ratio (PSR) increased with time as the P rate increased. Lower M1-P and PSR values were measured with St. Augustinegrass, which absorbed more P than did zoysiagrass. Th e root system of St. Augustinegrass was larger and deeper compared with zoysiagrass, promoting greater P uptake and less P leaching. If tissue analysis indicates that P fertilization is required and the soil has the capacity to retain additional P, application of 0.8 g P m-2 yr-1 to zoysiagrass and 1.07 g P m-2 yr-1 to St. Augustinegrass is appropriate and does not result in increased Pi leaching. [ABSTRACT FROM AUTHOR]

Growing concern over the sufficiency and variability of present water supplies in the arid Southwest has led to the examination of buffalograss [Buchloe dactyloides (Nutt.) Engelm.] for water conservation. Increasing acceptance of buffalograss will require investigation into conversion techniques for its establishment. The objectives of this study were to evaluate the effects of seedbed preparation and seeding rate on the establishment of buffalograss after bermudagrass desiccation with glyphosate. Research was conducted at the Texas Tech Quaker Research farm in 2009 and 2010 on a mature 'Riviera' common bermudagrass [Cynodon dactylon (L.) Pers.] rough. Bermudagrass was sprayed with glyphosate at 1.1 kg acid equivalent (ae)/ha 5 and 1 weeks before seedbed preparation. Plots were scalped after desiccation. Treatments were arranged in a two x four factorial, randomized complete block design with four replications, two buffalograss seeding rates and four seedbed preparation treatments. Seedbed preparation treatments consisted of no seedbed preparation, topdressing alone (0.6-cm layer), holiow-tine aerification + topdressing, or verticutting + topdressing. 'TopGun' buffalograss was planted on 1 June 2009 and 4 June 2010 at 146 or 195 kg⋅ha-1. Grid counts were conducted to determine buffalograss cover one, two, and three months after planting (MAP). Counts were then converted to percent cover (0% to 100%). Greater buffalograss cover was observed when seed was applied at the higher rate (196 kg⋅ha-1) except within treatments that did not receive seedbed preparation treatment. No seedbed preparation resulted in unacceptable buffalograss cover. Percent buffalograss cover three MAP was 75%, 83%, and 86% for topdressing alone, aerification + topdressing, and verticutting + topdressing treatments seeded at 195 kg⋅ha-1, respectively. [ABSTRACT FROM AUTHOR]

BACKGROUND: Neonicotinoid insecticides are generally efficacious against many turfgrass pests, including several important phloem-feeding insects. However, inconsistencies in control of western chinch bugs, Blissus occiduus, have been documented in field efficacy studies. This research investigated the efficacy of three neonicotinoid insecticides (clothianidin, imidacloprid and thiamethoxam) against B. occiduus in buffalograss under field conditions and detected statistically significant differences in B. occiduus numbers among treatments. A subsequent study documented the relative quantity and degradation rate of these insecticides in buffalograss systemic leaf tissues, using HPLC. RESULTS: Neonicotinoid insecticides initially provided significant reductions in B. occiduus numbers, but mortality diminished over the course of the field studies. Furthermore, while all three neonicotinoids were present in the assayed buffalograss leaf tissues, imidacloprid concentrations were significantly higher than those of clothianidin and thiamethoxam. Over the course of the 28 day study, thiamethoxam concentrations declined 700-fold, whereas imidacloprid and clothianidin declined only 70-fold and 60-fold respectively. CONCLUSIONS: Field studies continued to verify inconsistencies in B. occiduus control with neonicotinoid insecticides. This is the first study to document the relative concentrations of topically applied neonicotinoid insecticides in buffalograss systemic leaf tissues. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Pesticides are developed with carriers to improve their physicochemical properties and, accordingly, the bioefficacy of the applied formulation. For foliar-applied herbicide, generally less than 0.1% of the active ingredient reaching the target site could reduce pesticide performance. Recently, a carrier of nanoemulsion consisting of oil, surfactant and water, with a particle size of less than 200 nm, has been shown to enhance drug permeability for skin penetration in pharmaceutical delivery systems. In the present work, the aim was to formulate a water-soluble herbicide, glyphosate isopropylamine (IPA), using a green nanoemulsion system for a biological activity study against the weeds creeping foxglove, slender button weed and buffalo grass. RESULTS: The nanoemulsion formulations displayed a significantly lower spray deposition on creeping foxglove (2.9-3.5 ng cm−2), slender button weed (2.6-2.9 ng cm−2) and buffalo grass (1.8-2.4 ng cm−2) than Roundup® (3.7-5.1 ng cm−2). The visible injury rates of weeds treated with the nanoemulsion formulations were statistically equivalent to those relating to Roundup® at 14 days after treatment, with a control range of 86.67-96.67%. CONCLUSION: It was hypothesised that the significant difference in spray deposition with equal injury rates can be attributed to enhanced bioactivity of the nanoemulsion formulations. This initial discovery could be the platform for developing better penetration of agrochemical formulations in the future. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

After considering certain fundamental aspects of Quintilian's conception of rhetoric and that of St. Augustine, and their position on philosophy, especially Stoicism and Platonism, the author of this article analyzes the importance of tropes and figures to both authors, within the context of elocutio. Special emphasis is placed on those particular tropes and figures that allow for a better understanding of things and, therefore, are of capital relevance in the realm of philosophical knowledge, as the latter is expressed through language. [ABSTRACT FROM AUTHOR]