Tall Fescue Plots Research Articles

Mowing height and irrigation effects on above ground biomass production of Schedonorus arundinaceus

AbstractThe utilization of biomass from golf course and home lawn landscapes greatly impacts soil conditions, plant health, and municipal waste disposal. In 2020 and 2021, research was conducted to evaluate aboveground biomass production of tall fescue (Schedonorus arundinaceus Schreb.) in relation to mowing height. Irrigated and non‐irrigated plots of tall fescue were mown to 5.08, 6.35, and 7.62 cm. Biomass yields were determined by dried clipping weight. In general, 5.08 and 7.62 cm mowing height treatments consistently produced the greatest and lowest biomass yields, respectively. With few exceptions, results were consistent between irrigated and non‐irrigated trials. For tall fescue, findings suggest an inverse relationship between height of cut (HOC) and aboveground biomass production. Regardless of irrigation, tall fescue clipping yields declined when mown at a greater HOC.

Effect of mowing timing and clipping collection practices on azoxystrobin distribution, persistence, and efficacy

AbstractPrevious research suggests mowing practices following azoxystrobin application alter pest control and residue fate. Azoxystrobin, an acropetal penetrant quinone outside inhibitor fungicide, is commonly applied in turfgrass and other agricultural settings, protecting desired plants from fungal pathogens by inhibiting fungal growth. Field research was initiated in Raleigh, NC, and repeated in time to assess the effect of post‐application mowing timing and clipping collection practices on azoxystrobin residue persistence in tall fescue (Schedonorus arundinaceus Schreb.). At trial initiation, azoxystrobin was applied at the maximum single application rate (0.61 kg ai ha−1) to tall fescue plots. To determine the effect of initial mowing timing, plots were mowed (9.5 cm) at 0, 1, 2, 3, 7, or 14 days after application (DAA). To determine the effect of clipping removal, plots were mowed at 3, 10, and 17 DAA and clippings were either returned to the canopy or bagged and removed. Concurrently, soil cores (92 cm2) were collected at 3, 7, 14, and 21 DAA and then segmented into remaining aboveground vegetation and soil (0.0‐ to 2.5‐cm depth) for residue analyses. Mowing timing affected azoxystrobin residue in the vegetation and in soil. When clippings were returned to the canopy, 5% more azoxystrobin was detected in the vegetation at 7 and 14 DAA. At 3 and 7 DAA, in the soil, returning clippings resulted in >3% more of the applied azoxystrobin compared to removing clippings. Data from this research may allow for extended fungicide intervals for brown patch suppression and demonstrate the importance of returning clipping to turf systems to retain azoxystrobin residues.

Long-term fertilization and cultivation impacts on nematode abundance and community structure in tall fescue turfgrass.

Impacts of long-term fertilization and cultivation were evaluated on nematode communities associated with tall fescue turfgrass following 11 years of treatment applications. Fertilizer treatments of biosolid, synthetic, and plant-based fertilizers and cultivation treatments of 0×, 1×, and 2× aerification passes were applied to randomized and replicated tall fescue plots at the University of Maryland Paint Branch Turfgrass facility in College Park, Maryland. Free-living and plant-parasitic nematodes were identified, enumerated, and categorized into functional groups. Nematode count data were compared using generalized linear mixed modeling with negative binomial distribution and two-way ANOVA was used to compare nematode ecological indices. Biosolid treatments resulted in lower omnivore-predator densities than plant-based fertilizer treatments (p ≤ .001) and significantly greater Hoplolaimus densities than plant-based fertilizer plots (p ≤ .05). Synthetic fertilizer applications resulted in the greatest Eucephalobus (p ≤ .05) and total bacterivore densities (p ≤ .001) of all fertilizer treatments. Plant-based fertilizer-treated plots had the largest Maturity Index cp 2-5 and Structure Index (p ≤ .05). Cultivation of 1× resulted in fewer total bacterivore densities than 2× (p ≤ .01) while omnivore-predator densities were greater in 1× than 0× (p ≤ .001). Plant health, as measured by NDVI, was lowest in biosolid-treated turfgrass (p ≤ .05). These findings suggest that long-term turfgrass management practices can have variable impacts on nematode abundance and community structure in tall fescue and provide insights into ecological impacts of turfgrass management practices.

Prescribed burning of endophyte-infected tall fescue plots: Effects on forage production, ergot-like alkaloid concentrations, and botanical composition

Our objective was to evaluate the effects of early-spring prescribed fire on forage production and botanical composition in Kentucky 31 tall fescue plots. Treatments were applied in a completely randomized design with 10 plots per treatment. Treatments were (1) no burn (CON), (2) March mowed (MWD), (3) March burn (EBRN, early burn), and (4) April burn (LBRN, late burn). Beginning in May and repeated monthly until October, tall fescue tillers were hand clipped at ground level while walking an “X” pattern. In May of each year, tall fescue seedheads were counted in twelve 0.09-m2 quadrats per plot, and species frequencies were recorded. Species frequency was collected again in October. Tall fescue seedheads were reduced by 72% (P < 0.01) for LBRN. Spring forage accumulation was reduced (P < 0.01) by MWD, EBRN, and LBRN treatments, with EBRN and LBRN having a greater reduction (P = 0.03) than MWD. Nonfescue forage species frequency increased (P ≤ 0.01) in October for LBRN. Ergovaline concentration did not differ (P = 0.57) among treatments but differed (P = 0.01) by month, with a substantial increase in June compared with other months. Early-spring prescribed fire reduced tall fescue seedhead production; however, fire also reduced forage production. Removal of a portion of seedheads from tall fescue plots did not affect ergovaline concentration in plant samples. Thus, future research should evaluate ergot-like alkaloid concentrations in various plant parts from tall fescue subjected to seedhead control measures.

Do agricultural grasses bred for improved root systems provide resilience to machinery-derived soil compaction?

The increasing frequency of droughts and floods on grasslands, due to climate change, increases the risk of soil compaction. Soil compaction affects both soil and forage productivity. Differing grasses may counteract some effects of compaction due to differences in their root architecture and ontogeny. To compare their resilience to soil compaction, three Festulolium (ryegrass and fescue species’ hybrids) forage grass cultivars comprising differing root architecture and ontogeny were compared in replicated field plots, together with a ryegrass and tall fescue variety as controls. Pre‐compaction soil and forage properties were determined in spring using > four‐year‐old plots to generate baseline data. Half of each field plot was then artificially compacted using farm machinery. Forage dry matter yield (DMY) was determined over four cuts. After the final harvest, post compaction soil characteristics and root biomass (RB) were compared between grasses in the non‐compacted and compacted soils. Pre‐compaction data showed that soil under Festulolium and ryegrass had similar water infiltration rates, higher than soil under tall fescue plots. Tiller density of the Festulolium at this time was significantly higher than fescue but not the ryegrass control. Forage DMY was significantly lower (p < .001) with compacted soil at the first cut but, by the completion of the growing season, there was no effect of soil compaction on total DMY. Tall fescue had a higher total DMY than other grasses, which all produced similar annual yields. Soil bulk density and penetration resistance were higher, and grass tiller density was lower in compacted soils. Root biomass in compacted soils showed a tendency for Festulolium cv Lp × Fg to have higher RB than the ryegrass at 0–15 cm depth. Overall, findings showed alternative grass root structures provide differing resilience to machinery compaction, and root biomass production can be encouraged without negative impacts on forage productivity.

Irrigation scheduling technologies reduce water use and maintain turfgrass quality

AbstractSmart irrigation controllers have demonstrated potential for turfgrass water conservation in humid and temperate environments but have not been comprehensively tested in arid environments. The objective of this study was to determine the accuracy of a wireless capacitance sensor over a wide soil moisture range and to ascertain if smart irrigation controllers resulted in water savings without reducing quality of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] and bermudagrass (Cynodon dactylon L.). A two‐yr study was conducted to compare turfgrass quality, root morphology, and water use of plots irrigated with a constant run time to plots for which irrigation was scheduled using soil moisture sensors (SMS), evapotranspiration (ET) [Climate Logic (CL)] controllers, or 80% of historic ET (ET80) for tall fescue and 60% (ET60) for bermudagrass. Sensors accurately tracked soil moisture up to salinity levels of 4 dS m−1. Turf performance and root morphology were not affected by irrigation treatments for either grass. Compared to tall fescue plots irrigated with constant run time, plots irrigated using ET80 and CL required 38% less water, and SMS plots used 44% less than tall fescue. Scheduling bermudagrass irrigation by ET60, CL, and SMS resulted in a 29, 42, and 39% reduction in water applied compared to constant run time. The majority of water savings was in spring and fall. Water requirement for bermudagrass during the summer did not differ between the scheduling treatments. Our study confirms that smart irrigation controllers can be used as an effective measure to conserve water in an arid environment.

261 Prescribed burning of endophyte-infected tall fescue pastures: Effects on forage production, ergot alkaloid concentrations, and stand composition

Abstract Prescribed fire may be a non-chemical alternative for seedhead suppression in endophyte-infected tall fescue forage systems. A study was conducted to observe the effects of a single prescribed burn on seed head production, ergot alkaloid concentration, forage production, forage quality, and stand composition in K31 tall fescue plots (endophyte infection=96%). Treatments of an undisturbed control (CON), March mow (MOW), March burn (EARLY), and April burn (LATE) were randomly applied to 56 square meter plots with ten replicates per treatment. Plots were sampled for forage quality and ergot alkaloid concentrations monthly from May to October. Forage production and species composition was recorded in June and October. Fescue seedhead count was conducted in May. After June sampling, plots were clipped to a height of 10 cm and litter was removed to simulate spring grazing. CON had greater (P &amp;lt; 0.01) total forage production in June than other treatments. MOW had greater (P &amp;lt; 0.01) forage production (≤107 kg/ha) than EARLY and LATE in June. There was no effect (P = 0.30) of treatments on forage production in October. LATE burn reduced (month × trt; P = 0.02) ergovaline concentration in June but all treatments were above the established threshold (150 ppb) for fescue toxicosis. Fescue seed head frequency was decreased (P &amp;lt; 0.01) by 50% in LATE plots. There was no treatment effect (P ≥ 0.22) on forb and non-fescue grass frequency in May, but warm season grass frequency was greater (P &amp;lt; 0.01) in LATE plots in October. Crude protein in LATE was greater than other treatments in May and both LATE and CON were greater than other treatments in June (P &amp;lt; 0.01). Neutral detergent fiber for LATE was less than other treatments in May and June (P &amp;lt; 0.01). Under conditions of this experiment, prescribed fire decreased seed head count and ergot alkaloid concentration, with a modest reduction in forage production.

Evaluation of Key Methodology for Digital Image Analysis of Turfgrass Color Using Open‐Source Software

Digital image analysis is a frequently used research technique to provide an objective measure of turfgrass color, in addition to the traditional visual rating. A commonly used method relies on commercial software package SigmaScan Pro to quantify mean hue angle, saturation, and brightness values from turf images, and to calculate a dark green color index as the measure of color. To enable turf image analysis to function on an open‐source platform, a method was developed within ImageJ to batch process turf images for color parameters. This Java‐based ImageJ plugin quantifies hue angle, saturation, and brightness values and calculates a dark green color index. In addition, information on the variability of these color parameters can be simultaneously acquired. This new method was used to quantify color parameters of turf images collected from field plots of tall fescue (Schedonorus arundinacea Shreb. Dumort.), Kentucky bluegrass (Poa pratensis L.), ryegrass (Lolium ssp.), hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy), and creeping bentgrass (Agrostis stolonifera L.). While color parameter values differed little between ImageJ and SigmaScan, the time saved in processing images using ImageJ was considerable. Aside from software, analysis of color parameters acquired from the five turfgrass species indicated that hue angle alone can adequately measure turf color in digital images. Results also demonstrated that, in addition to light source, camera settings should remain fixed during photo capture to avoid introducing errors. The ImageJ plug‐in developed in this study is made available at www.turffiles.ncsu.edu.

Fungicide Management of Brown Patch of Tall Turf-type Fescue in the Residential Landscape in Oklahoma

In the transition zone of the USA, cool-season grasses such as tall fescue are often planted in shaded areas, where warm-season grasses are less adapted. The most damaging disease of tall fescue is brown patch, caused by Rhizoctonia solani. Fungicide applications and cultural practices are often used to manage brown patch in this region. A three-year study was implemented in Oklahoma to evaluate ready-to-use fungicides available to residential lawn owners and compare these to several common commercial fungicide formulations used by professional lawn care applicators. A selection of fungicides representing products commonly available to the residential market and commercial standards were applied to small plots of tall fescue or tall fescue/Kentucky bluegrass mixtures from 2008 to 2010. All products tested, with the exception of azoxystrobin, provided limited or inconsistent control of brown patch and resulted in lower turfgrass quality in all years. Further examination of carrier type (granular vs. liquid) and timing (preventive vs. curative) did not result in strong differences in the level of brown patch control or overall quality. These studies suggest that control of brown patch in tall fescue in the transition zone should focus on integrated disease management principals and not only on applications of fungicides directed at the residential market. Accepted for publication 5 August 2013. Published 22 October 2013.

LIMING OF TWO ACIDIC SOILS IMPROVED GRASS TETANY RATIO OF STOCKPILED TALL FESCUE WITHOUT INCREASING PLANT AVAILABLE PHOSPHORUS

Previous research demonstrated that phosphorus (P) fertilization of tall fescue (Festuca arundinacea Schreb.) pastures on acidic soils increased leaf P, magnesium (Mg), and calcium (Ca) concentrations and reduced the risk of grass tetany. It has been suggested that liming could have a similar effect by increasing soil pH and remobilizing sorbed P. To investigate this option, calcitic or dolomitic limestone was applied to stockpiled tall fescue plots on two acidic soils, a fragipan and a claypan. As expected, increasing rates of limestone were correlated with higher soil pHs. Contrary to predictions, limestone applications had very little effect on soil or plant P. However, both types of limestone at both locations altered leaf macronutrient concentrations in a manner that improved the grass tetany equivalent ratio: increased Ca and/or Mg and decreased K concentrations, thus lowered the likelihood of grass tetany in grazing beef cattle.

The Effect of Spike-Tooth Aeration on Tall Fescue Yield

Over the last several years, spike-tooth aerators have been promoted as a tool to increase yield of grass pastures and hayfields across the Southeast. A two-year research project was conducted at two locations in Tennessee to evaluate the effect of spike-tooth aeration on the yield of tall fescue (Festuca arundinacea Schreb.). At the East Tennessee Research and Education Center and the Middle Tennessee Research and Education Center tall fescue plots were aerated once, either in spring or fall. Plots were fertilized with N at 60 lb/acre at spring green-up and harvested when forage height reached 8 to 10 inch. Results from both locations showed that aeration had no effect on tall fescue yield.

Foraging preferences of captive Canada geese related to turfgrass mixtures

Overabundant populations of Canada geese (Branta canadensis) cause economic and safety concerns associated with collisions with civil and military aircraft. Habitat management techniques that reduce the use of airfield habitats by geese might reduce these concerns. The objective of this study was to determine if captive Canada geese exhibited a foraging preference between a vegetation mixture consisting mostly of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) versus an endophyte-infected tall fescue- (Festuca arundinacea) based vegetation mixture. We established 6 paired plots of perennial ryegrass-dominated and tall fescue-dominated mixtures at NASA Plum Brook Station in north-central Ohio during 2000. Behavioral observations of captive Canada geese were conducted during 2001 and 2003. In 2001, ryegrass plots contained 4% perennial ryegrass and 94% white clover. Fescue plots contained 72% tall fescue and 6% clover. The numbers of geese observed in ryegrass plots([overhead single bar]x=2.0 geese/plot, SE = 0.35) and tall fescue plots ([overhead single bar]x = 1.9 geese/plot, SE = 0.33) were not different (F1,10 = 0.03, P = 0.86). Foraging by captive Canada geese was similar (F1,10 = 0.26, P = 0.62) in the perennial ryegrass plots ([overhead single bar]x = 12.8 bill contacts/minute/4 geese, SE = 1.4) and the tall fescue plots ([overhead single bar]x = 11.2 bill contacts/minute/4 geese, SE = 2.9). In 2003, ryegrass plots contained 42% perennial ryegrass and 20% white clover. Fescue plots contained 91% tall fescue. The number of captive geese observed in ryegrass plots ([overhead single bar]x = 3.0 geese/plot, SE = 0.19) was greater (F1,10 = 56.9, P<=0.001) than in the fescue plots ([overhead single bar]x = 1.0 geese/plot, SE = 0.19). Foraging by Canada geese was greater (F1,10 = 346.5, P<=0.001) in the ryegrass plots ([overhead single bar]x = 30.7 bill contacts/minute/4 geese, SE = 1.55) than in the tall fescue plots ([overhead single bar]x = 0.8 bill contacts/minute/4 geese, SE = 0.41). Our findings suggest tall fescue might be a favorable species to be used in reseeding and vegetation renovation projects in areas where Canada geese are a potential problem. We recommend field trials be conducted in various parts of the United States to determine which high-endophyte tall fescue varieties might be useful for goose management in different physiographic regions of North America.

Soil biota associated with endophyteinfected tall fescue in the field

Invertebrates present in soil samples taken from plots of tall fescue (Festuca arundinacea) infected with two nontoxic strains of Neotyphodium endophyte (AR501 and AR542) at Aorangi near Palmerston North and one strain (AR501) at Lincoln in Canterbury together with endophytefree controls at both sites were determined in autumn 2002 Roots taken from these samples were stained and checked for the presence of arbuscular mycorrhiza At Lincoln numbers of root aphid (Aploneura lentisci) associated with plants infected with AR501 were significantly less than those on endophytefree plants while grass grub numbers (Costelytra zealandica) did not differ between treatments Beneficial invertebrates Collembola mites and earthworms were not affected by endophyte at either site and neither was colonisation of roots by mycorrhiza

Preemergence Herbicide and Seeding Method Effects on Seedling Growth of Kentucky Bluegrass1

Turfgrass managers often desire to overseed thin areas during midsummer or late summer, but seeding desirable species too soon after a preemergence herbicide application can interfere with seedling growth. This study was conducted to compare the effects of three herbicides on Kentucky bluegrass seedling growth and to determine whether seeding method affects the interval before seeding can safely occur. Dithiopyr, prodiamine, and pendimethalin were applied to ‘Kentucky 31’ tall fescue plots in late April at 0.56, 0.84, and 3.36 kg ai/ha, respectively. At 2, 4, 8, 12, and 16 wk after treatment, soil cores were extracted from each plot, the existing turf was killed, and the cores were either broadcast seeded or slit seeded with Kentucky bluegrass. Slit seeding resulted in greater and more extended seedling growth suppression than broadcast seeding for all herbicides. Prodiamine suppressed Kentucky bluegrass seedling growth longer than dithiopyr and pendimethalin. Unacceptable seedling growth suppression occurred unless broadcast seeding was delayed for about 6, 8, and 14 wk after dithiopyr, pendimethalin, and prodiamine application, respectively. The required interval between herbicide application and slit seeding was approximately 11, 10, and 16 wk, respectively. Use of dithiopyr or pendimethalin rather than prodiamine and broadcast seeding instead of slit seeding allows earlier overseeding with Kentucky bluegrass.Nomenclature: Dithiopyr; pendimethalin; prodiamine; Kentucky bluegrass, Poa pratensis L. #3 POAPR ‘Unique’; tall fescue, Festuca arundinacea Schreb. # FESAR ‘Kentucky 31’.Additional index words: Broadcast seeding, overseeding, seeding interval, slit seeding, vertical mowing.Abbreviation: WAT, weeks after treatment.

Water Use and Physiological Response of Tall Fescue Turf to Water Deficit Irrigation in an Arid Environment

Research was conducted to assess the response of tall fescue (Festuca arundinacea Schreb.) to water deficit conditions. Different leaching fractions (LF = drainage volume/irrigation volume) and irrigation frequencies (IF) were imposed over a 119-day summer period in Las Vegas, Nevada, followed by a 71-day recovery period. Plots of tall fescue contained 120 cm deep × 51 cm diameter draining lysimeters. Irrigations were based on an evapotranspiration (ET) feedback system to establish LFs of +0.15, 0.00, -0.15, -0.25, and -0.40. Plots were irrigated on a daily or twice per week schedule. N was applied to subplots at a rate of 0, 12.2, or 24.4 kg·ha-1 per month. As LF decreased, relative soil water in storage declined in a linear fashion (r2 = 0.97, P = 0.001). Storage depletions for the four lowest LFs at the end of 119 days of imposed water deficits were about 15%, 40%, 60%, and 70% compared to the +0.15 LF treatment. Canopy temperature, soil matric potential (Ψm), leaf xylem water potential (ΨLX), leaf stomatal conductance (gs), clipping yield, color and cover ratings all statistically separated (P &lt; 0.05) based on LF but not on IF. However, irrigation amount (I), ET, tissue moisture content and total Kjeldahl N (TKN) separated based on LF and IF with a significant LF by IF interaction for I (P &lt; 0.05) and TKN (P &lt; 0.001). An irrigation savings of 60.4 cm was realized during the 119-day water deficit period at the -0.40 LF. However, at the lower LFs, plant stress increased (all parameters) with color ratings declining below an acceptable value of 8.0. An Irrigation/Potential ET (I/ETo) threshold of 0.80 was determined for both color and cover. After a 71-day recovery period both color and cover returned to pre experimental values at the two higher N rates. Results of this experiment indicate that implementing a twice weekly irrigation strategy at a -0.15 LF on tall fescue during summer months in an arid environment would lead to savings of 37.5 cm of water while still maintaining acceptable color and cover ratings.

UV‐B Biodosimetry in Turfgrass Canopies

Phylloplane microorganisms are affected by ultraviolet (UV) radiation penetrating into plant canopies, but data as to the relationships between microorganism activity and canopy UV levels is lacking. Current instrumentation and modeling systems are inadequate to analyze canopy radiation environments at scales relevant to microorganisms. A biological dosimeter system was developed for measuring UV‐B in turfgrass and other compact canopies. Cell suspensions of a DNA repair‐deficient strain of Escherichia coli (CSRO6) were enclosed in packets (0.2‐mL volume) of UV‐transmissible polyethylene. After the packets were exposed to sunlight, numbers of surviving bacteria were determined. The log percent survival was found to be linearly related to accumulative UV‐B dosage, as measured with a broad‐band UV‐B radiometer, but was not related to UV‐A dosage. In one experiment, the performance of the biodosimeter system was compared with that of a miniature UV‐B radiometer mounted in soil‐level tracks in eight plots of tall fescue (Festuca arundinacea Schreb.) that varied in leaf area index (LAI). The two methods yielded similar mean transmittance values that decreased with increasing LAI, closely fitting Beer's law. A similar relationship was found in a second experiment, in which biodosimeter packets were placed at the base of undisturbed tall fescue canopies. The packets also revealed considerable variation in transmittance possibly because of localized shading and sun flecks in the natural canopies. In a third experiment, direct and diffuse UV‐B at different heights within a tall fescue canopy was measured by packets attached to narrow, flat wooden sticks simulating grass leaves. This method has potential as a tool to capture the variability in UV levels related to nonuniformity in canopy structure, depth in a canopy, and leaf orientation.

UV-B Biodosimetry in Turfgrass Canopies

Phylloplane microorganisms are affected by ultraviolet (UV) radiation penetrating into plant canopies, but data as to the relationships between microorganism activity and canopy UV levels is lacking. Current instrumentation and modeling systems are inadequate to analyze canopy radiation environments at scales relevant to microorganisms. A biological dosimeter system was developed for measuring UV-B in turfgrass and other compact canopies. Cell suspensions of a DNA repair-deficient strain of Escherichia coli (CSRO6) were enclosed in packets (0.2-mL volume) of UV-transmissible polyethylene. After the packets were exposed to sunlight, numbers of surviving bacteria were determined. The log percent survival was found to be linearly related to accumulative UV-B dosage, as measured with a broad-band UV-B radiometer, but was not related to UV-A dosage. In one experiment, the performance of the biodosimeter system was compared with that of a miniature UV-B radiometer mounted in soil-level tracks in eight plots of tall fescue (Festuca arundinacea Schreb.) that varied in leaf area index (LAI). The two methods yielded similar mean transmittance values that decreased with increasing LAI, closely fitting Beer's law. A similar relationship was found in a second experiment, in which biodosimeter packets were placed at the base of undisturbed tall fescue canopies. The packets also revealed considerable variation in transmittance possibly because of localized shading and sun flecks in the natural canopies. In a third experiment, direct and diffuse UV-B at different heights within a tall fescue canopy was measured by packets attached to narrow, flat wooden sticks simulating grass leaves. This method has potential as a tool to capture the variability in UV levels related to nonuniformity in canopy structure, depth in a canopy, and leaf orientation.

Poultry Litter and Grazing Animal Waste Effects on Runoff Water Quality

AbstractIn complex landscapes with multiple land uses, it is often difficult to identify the source of contaminant loadings. The objective of this study was to compare nutrient runoff as affected by grazing animal depositions vs. poultry litter application. Simulated rainfall was applied twice to 1.5 by 6.0 m runoff plots of tall fescue (Festuca arundinacea Schreb.) with treatments of no waste (CT), dairy calf feces and urine (DFU), poultry litter (PL), and dairy calf feces and urine with poultry litter (DFU + PL). Chemical properties of the runoff samples including pH, electrical conductivity (EC), C, soluble reactive phosphorus (SRP), total nitrogen (TN), NH4‐N, NO3‐N, K, Mg, S, B, Cu, Fe, Mn, Mo, Na, and Zn were determined. Plots receiving poultry litter had significantly greater losses of most nutrient parameters for both rainfall simulations. For the nutrient parameters of primary interest with regard to water quality, 5.0, 29.5, and 21.9% of the TN, NH4‐N, and SRP applied in the PL treatment were transported in runoff during the first rainfall simulation as compared to 3.9, 5.0, and 15.3%, respectively, for the DFU treatment. Comparable percentages of the applied nutrients were lost from the PL and DFU treatments even though the PL treatment, with the exception of NH4‐N, provided at least six times the amount of each nutrient. A severe rainfall event shortly after poultry litter application produces significantly greater nutrient losses as compared to similar application of grazing animal depositions at the rates used in the experiment.

Effects of plant growth regulators and fungicides on Rhizoctonia blight of tall fescue

In field experiments conducted in 1996 and 1997, the plant growth regulators (PGRs) flurprimidol, paclobutrazol and trinexapacethyl were applied individually to plots of tall fescue, Festuca arundinacea Schreb., cv. Rebel II at rates of 0.8, 0.6 and 0.3 kg a.i. ha −1. Twenty-four hours later, the fungicides propiconazole, iprodione, chlorothalonil, flutolanil and azoxystrobin were applied individually to the PGR-treated plots at rates of 1.7, 3.0, 6.0, 6.1, and 0.8kg a.i. ha −1, respectively. Nontreated plots and plots treated with the PGRs or fungicides alone served as controls. Four hours after the fungicide applications, the turfgrass was inoculated with Rhizoctonia solani AG1IA, the cause of Rhizoctonia blight, and disease severity was assessed visually from 5 July to 2 August 1996, and from 27 June to 23 July 1997. In 1996, the PGR treatments had no significant effect on the severity of Rhizoctonia blight when compared to nontreated plots. Results were similar in 1997 with the exception that disease was significantly suppressed ( P < 0.05) in plots treated with paclobutrazol 15 and 22 days after treatment. In both years, the propiconazole, flutolanil and azoxystrobin treatments significantly suppressed Rhizoctonia blight ( P < 0.05) for at least 28 days when compared to a nontreated check, while iprodione and chlorothalonil resulted in significant disease suppression for at least 21 days. At the rates tested, flutolanil and azoxystrobin were the only fungicides tested that limited disease severity to < 10% for more that 28 days in each year of the study. Severity of Rhizoctonia blight was significantly greater ( P < 0.05) on at least one assessment date in each year in plots treated with trinexapacethyl+propiconazole or with any of the PGRs tested+iprodione compared to plots treated with the fungicides alone. However, with the exception of a significant increase in disease in plots treated with paclobutrazol+chlorothalonil late in the 1996 epidemic, the remaining PGR+fungicide treatments had no significant effects on disease severity when compared to the effects of the fungicides alone.

Bioextraction of Soil Boron by Tall Fescue

High concentrations of soil B are detrimental to crop productivity in certain arid and semiarid regions of the western United States. Production of tall fescue on B-affected soils may be a viable strategy to reduce and maintain soil B concentrations at nontoxic levels for most agronomic crops. A 2-year field experiment was conducted to study B uptake in tall fescue ( Festuca arundinacea) Schreb, cv. Au Triumph grown in soil containing potentially toxic levels of native soil B. The soil B concentrations (water-extractable B greater than 5 mg B liter −1) did not affect the dry matter (DM) yield of tall fescue. Boron concentrations in shoot tissue for both years ranged from 88 to 121 mg B kg −1 DM, whereas in root tissue, concentrations ranged from 50 to 60 mg B kg −1 DM. For both years of the study, soil samples were taken at depth of 0-45 and 45-90 cm at the beginning and end of the designated growing season and analyzed for water-extractable B. Summary data from all cropped plots at the two soil depths indicated that the mean water-extractable B concentrations were reduced by 35% after 2 years in the tall fescue plots, whereas losses of extractable B from bare plots did not exceed 13% for both years. Tall fescue apparently can be used as a component in an overall strategy to lower extractable soil native B levels in irrigated agriculture soils and potentially reduce leaching of B into shallow ground water.