Creeping Bentgrass Turf Research Articles

Plant growth regulators differentially suppress goosegrass and smooth crabgrass in creeping bentgrass turf

Abstract Goosegrass and smooth crabgrass in creeping bentgrass turf are difficult to control due to a lack of selective herbicides. Based on preliminary field observations, we hypothesized that paclobutrazol and flurprimidol would reduce the overall competitiveness of goosegrass and smooth crabgrass in creeping bentgrass. Greenhouse and field studies were designed to evaluate the effect of several plant growth regulators (PGRs) on goosegrass and smooth crabgrass competitive indices. In greenhouse studies, flurprimidol, paclobutrazol, trinexapac-ethyl, and prohexadione-calcium were applied either preemergence only or preemergence plus two biweekly postemergence applications to goosegrass and smooth crabgrass plants to simulate the first 1.5 mo of typical PGR programs used on golf courses. Two weeks after the final postemergence treatment, aboveground biomass and root biomass were recorded. Programmatic flurprimidol and paclobutrazol applications reduced smooth crabgrass aboveground biomass by 67% and 69%, respectively, and more than trinexapac ethyl or prohexadione-calcium. When averaged across application programs, flurprimidol and paclobutrazol reduced smooth crabgrass root biomass by 74% and goosegrass biomass by 73% to 80%. Field studies were established to further evaluate the influence of PGRs on smooth crabgrass coverage in creeping bentgrass turf. Treatments consisting of flurprimidol, trinexapac-ethyl, flurprimidol plus trinexapac-ethyl, paclobutrazol, and fenoxaprop-p were applied every 3 wk from April to August. Weed coverage data were collected throughout the growing season, and final smooth crabgrass control data were collected at the end of the season. In general, flurprimidol-containing treatments more effectively reduced smooth crabgrass coverage throughout the growing season than trinexapac ethyl. After the studies, regimens that contained flurprimidol controlled smooth crabgrass by 68% to 73%, greater than any other PGR program evaluated. Results from these studies indicate that flurprimidol may be used to effectively control smooth crabgrass or goosegrass in creeping bentgrass turf. These are the first reported data regarding the use of flurprimidol for smooth crabgrass or goosegrass control in turf.

Utilizing organic amendments for general suppression of dollar spot on creeping bentgrass turf

AbstractDollar spot (Clarireedia spp.) negatively impacts the aesthetic value and playability of golf course fairways. A 2‐yr field trial was conducted to examine organic amendment effect on dollar spot severity and on fungicide residual efficacy for dollar spot control on creeping bentgrass (Agrostis stolonifera L. ‘007’). Treatments were arranged in a 7 × 5 split‐plot factorial measuring the effect of fertilizer source (soil incorporated organic biosolids compost, soil incorporated biochar, surface applied organic biosolids compost, surface applied biochar, vermicompost extract, standard fertilizer, or non‐treated) on control of dollar spot by five fungicide treatments (fluazinam 14 d, fluxapyroxad 14 d, fluazinam threshold, fluxapyroxad threshold, none) applied at product label rates. Nitrogen fertility levels for all treatments were standardized at ∼205 kg N ha–1 annually. Threshold fungicide treatments were applied when three or more infection centers per area were counted on two or more of four trial replicates. In 2017, all fertilizer treatments were significantly more effective at reducing disease than non‐treated, but were statistically similar. In 2018, biochar, vermicompost, and standard fertilizer treatments were significantly more effective than organic biosolids compost and non‐treated. Fungicides controlled dollar spot when applied every 14 d. In 2017, all fertilizer treatments reduced the number of threshold sprays compared to none, yet the same effects were not consistently observed in 2018. Study results illustrate the effectiveness of nitrogen application for mitigating dollar spot disease on creeping bentgrass during establishment compared to no fertilizer, potentially allowing for reduced fungicide use to control the disease.

Plant growth regulator and low‐dose herbicide programs for annual bluegrass seedhead suppression in fairway and athletic‐height turf

AbstractAnnual bluegrass (Poa annua L.) seedhead suppression in fairway‐ or athletic‐height turf has become more challenging with the loss of mefluidide, leaving ethephon as the primary annual bluegrass seedhead suppression product. Ethephon programs to suppress annual bluegrass seedheads can cost up to 4.5 times more than that of mefluidide. New options are needed to either improve seedhead suppression programs on fairway‐ or athletic‐height turf or reduce cost associated with use on large areas. Six field research trials were conducted in Blacksburg, VA, to evaluate novel low‐dose herbicide programs and alternate plant growth regulators for mixture with and comparison to ethephon for annual bluegrass seedhead suppression and Kentucky bluegrass (P. pratensis L.) or creeping bentgrass (Agrostis stolonifera L.) response. In two separate studies, ethephon applied in December, February, and March suppressed annual bluegrass seedheads 36–39% per day based on area under the progress curve (AUPC). When mixed with ethephon, ethofumesate at 420 g a.i. ha−1, trinexapac‐ethyl at 95 g a.i. ha−1, and prohexadione calcium at 174 g a.i. ha−1 increased seedhead suppression by 34, 14, and 16%, respectively, over that of ethephon alone. Endothall at 140 g a.i. ha−1 also improved seedhead suppression when mixed with ethephon but was too injurious to Kentucky bluegrass and creeping bentgrass turf for commercial use. These studies suggest that low‐dose herbicide treatments or additional plant growth regulator admixtures with ethephon can improve annual bluegrass seedhead suppression in fairway‐ or athletic‐height turf.

Surfactant Effects on Creeping Bentgrass and Annual Bluegrass Exposed to Different Irrigation and Traffic Stress Treatments

Core Ideas Automated irrigation can be set below optimal levels while using a soil surfactant.A soil surfactant decreased soil water content when targeting above ideal irrigation.A soil surfactant increased turf quality and normalized difference vegetative index.Turf quality, under foot traffic, is improved with the use of a soil surfactant. Creeping bentgrass (Agrostis stolonifera L.) and annual bluegrass (Poa annua L.) are turfgrass species that experience water and excessive foot traffic stresses on putting greens. The objective of this study was to investigate whether a soil surfactant would play a role in promoting tolerance to excessive water, water deficit, and traffic stress on annual bluegrass and creeping bentgrass sand‐based rootzone putting greens. A soil surfactant was applied as a foliar spray (18.5 L ha−1) to creeping bentgrass cultivar Penn A‐4 and annual bluegrass field plots and watered‐in under three target soil volumetric water contents (SWC) (8, 12, and 16% SWC). Foot traffic was applied in summer 2013 and 2014 with a traffic simulator to represent low traffic (5688 rounds of golf), moderate traffic (11,376 rounds of golf), and no traffic (control). The effect of a soil surfactant on turfgrass quality, normalized difference vegetation index (NDVI), and SWC at two depths was measured. Statistical interactions existed between soil surfactant application and target SWC. Soil surfactant‐treated turfgrass affected SWC differently across irrigation regimens, with suboptimal (8% SWC) and excessive (16% SWC) resulting in increased and decreased moisture retention, respectively. Turf treated with a soil surfactant had greater turf quality than the untreated control in late summer in each year. A soil surfactant can increase annual bluegrass and creeping bentgrass turf quality during water deficit, excessive water, and/or foot traffic conditions.

Evaluation of individual and combined management practices to reduce the off-site transport of pesticides from golf course turf.

The detection of pesticides, associated with turfgrass management, in storm runoff and surface waters of urban watersheds has raised concerns regarding their source, potential environmental effects and a need for strategies to reduce their inputs. In previous research we discovered that hollow tine core cultivation (HTCC) was more effective than other management practices for reducing the off-site transport of pesticides with runoff from creeping bentgrass turf managed as a golf course fairway. This was primarily the result of enhanced infiltration and reduced runoff volumes associated with turf managed with hollow tines. In this study we evaluated the addition of verticutting (VC) to HTCC (HTCC+VC) in an attempt to further enhance infiltration and mitigate the off-site transport of pesticides with runoff from managed turf. Overall, greater or equal quantities of pesticides were transported with runoff from plots managed with HTCC+VC compared to HTCC or VC alone. For the pesticides evaluated HTCC<VC<HTCC+VC for the off-site transport of the high mobility pesticides while HTCC=VC=HTCC+VC for the low mobility pesticides. It is likely the addition of VC following HTCC further increased compaction and reduced availability of recently exposed soil sorptive sites produced from the HTCC. Results of this research provides guidance to golf course managers on selection of management practices that assure quality turf while minimizing off-site transport of pesticides, improving pesticide efficacy and the environmental stewardship of managed biological systems.

Predicting Microdochium Patch on Creeping Bentgrass

Microdochium patch is a major cool-season disease affecting creeping bentgrass (Agrostis stolonifera L.) on golf courses, yet prediction tools are limited to help properly time fungicide applications for control. The objective of this study was to create a predictive model using growth chamber studies to determine the effects of air temperature and leaf wetness duration on the development of Microdochium nivale on creeping bentgrass turf. ‘Penncross’ creeping bentgrass plants were inoculated with leaves infected with M. nivale and maintained in growth chambers while exposed to temperatures of 8, 12, 16, and 20°C at leaf wetness durations of 24, 36, 48, and 60 h. Digital images of diseased plants were measured for percentage area infected using Assess image analysis software. The effects of temperature and leaf wetness duration on disease were significant. Disease severity increased with temperature and leaf wetness durations. Among treatments, the most disease was measured at 20°C, 60 h (46.3% disease). Analysis of variance using orthogonal polynomial contrasts and regression analysis determined the relationships among temperature and leaf wetness duration to disease. The polynomial model included linear and quadratic terms for temperature and leaf wetness duration. The adjusted coefficient of determination for the fitted model was 0.70. The model may be tested in the field and used to help predict outbreaks of Microdochium patch on creeping bentgrass turf.

Impact of Antimicrobial Compounds on Etiolation Caused byXanthomonas translucensand on Turf Quality of Creeping Bentgrass Putting-Green Turf

Etiolation is an abnormal elongation and chlorosis of turfgrass plants that has become problematic in recent years, and bacteria have been implicated as causal agents. The frequent reports of etiolation are of concern to turfgrass managers, since management practices for bacterial diseases in turf are not well developed. The purpose of this research trial was to evaluate fungicides and nonregistered antibiotics for management of etiolation in creeping bentgrass turf. This 2-year field study evaluated oxytetracycline, streptomycin sulfate, acibenzolar-S-methyl + chlorothalonil (ASM + C), potassium phosphite (PPP), hydrogen dioxide, fosetyl-Al [pigmented (FAP) and nonpigmented (FA)], and copper + mancozeb for their effects on etiolation caused by Xanthomonas translucens on creeping bentgrass putting-green turf. Reductions in etiolation severity were observed with oxytetracycline treatment in both years and with ASM + C in the second year of study. While ASM + C did not reduce etiolation in the first year, turf quality with ASM + C alone and in combination with PPP was superior to all other treatments in both years. While PPP and FAP did not reduce etiolation, turf quality of these plots was often better than the control. Both antibiotics in addition to copper + mancozeb had phytotoxicity that reduced turf quality. Preventative applications of ASM + C were the most effective in reducing etiolation of creeping bentgrass while maintaining turf quality.

Evaluation of nitrogen and phosphorus transport with runoff from fairway turf managed with hollow tine core cultivation and verticutting

Enrichment of surface waters with excess nutrients is associated with increased algal blooms, euthrophication and hypoxic zones, as reported in the northern Gulf of Mexico. A source of nutrients to surface waters results from fertilizer runoff. Management strategies used to maintain turf on golf courses and recreational fields often include aerification and application of fertilizer. Although research exists on benefits of core cultivation and verticutting (VC) to reduce thatch and the transport of applied chemicals with runoff, there are no studies reporting the effect of coupling these management practices with the goal of further reduction of off-site transport of fertilizer with runoff. We hypothesized that the addition of VC to hollow tine core cultivation (HTCC) would enhance infiltration of precipitation, reduce runoff and nutrient transport with runoff and therefore influence concentrations of nutrients in surface waters receiving runoff from turf managed as a golf course fairway. Greater runoff and mass of soluble phosphorus and ammonium nitrogen transported with runoff were measured from plots managed with HTCC+VC than HTCC; however, the reverse was noted for nitrate nitrogen. Only a portion of the observed trends proved to be statistically significant. Our research showed no reduction or enhancement of risk associated with surface water concentrations of phosphorus or nitrogen, resulting from runoff from creeping bentgrass turf that was managed with HTCC+VC compared to HTCC. Data obtained in this research will be useful to grounds superintendents when selecting best management practices and to scientists seeking data relating runoff to land management for watershed-scale modeling.

Pesticide transport with runoff from creeping bentgrass turf: Relationship of pesticide properties to mass transport

The off-site transport of pesticides with runoff is both an agronomic and environmental concern, resulting from reduced control of target pests in the area of application and contamination of surrounding ecosystems. Experiments were designed to measure the quantity of pesticides in runoff from creeping bentgrass (Agrostis palustris) turf managed as golf course fairway to gain a better understanding of factors that influence chemical availability and mass transport. Less than 1 to 23% of applied chloropyrifos, flutolanil, mecoprop-p (MCPP), dimethylamine salt of 2,4-dichlorophenoxyacetic acid (2,4-D), or dicamba was measured in edge-of-plot runoff when commercially available pesticide formulations were applied at label rates 23 +/- 9 h prior to simulated precipitation (62 +/- 13 mm). Time differential between hollow tine core cultivation and runoff did not significantly influence runoff volumes or the percentage of applied chemicals transported in the runoff. With the exception of chlorpyrifos, all chemicals of interest were detected in the initial runoff samples and throughout the runoff events. Chemographs of the five pesticides followed trends in agreement with mobility classifications associated with their soil organic carbon partition coefficient (K(OC).) Data collected from the present study provides information on the transport of chemicals with runoff from turf, which can be used in model simulations to predict nonpoint source pollution potentials and estimate ecological risks.

Pythium Root Dysfunction of Creeping Bentgrass

Pythium root dysfunction (PRD), a disease of relatively young stands of creeping bentgrass turf, is commonly misdiagnosed as take-all patch. Symptoms of PRD typically appear during the summer months when creeping bentgrass is subjected to heat and drought stress, but patches may develop in the spring, fall, and winter during periods of warm and dry weather. This guide provides detailed information on PRD taxonomy, symptoms, range and distribution, isolation and storage, and more. Accepted for publication 29 October 2009. Published 25 January 2010.

Managing earthworm casts (Oligochaeta: Lumbricidae) in turfgrass using a natural byproduct of tea oil (Camellia sp.) manufacture

Earthworm casts are a worldwide problem on golf courses and sports fields when they disrupt the playability, aesthetics and maintenance of closely mowed playing surfaces. Currently, no pesticides are labeled for earthworms in the United States. Tea seed pellets (TSPs), a saponin-rich byproduct of Camellia oleifera Abel oil manufacture, were tested for expelling earthworms and reducing casts on creeping bentgrass turf. The fate of expelled worms, methods for removing them and impacts on pest and beneficial arthropods were also evaluated. Application of TSPs at 2.93 kg 100 m(-2), followed by irrigation, quickly expelled earthworms from the soil. A single application reduced casts by 80-95% for at least 5 weeks. Mowing or sweeping removed expelled earthworms from putting green surfaces. Most expelled earthworms burrowed down when transferred to untreated turf, but few survived. Bioassay-guided fractionation confirmed the vermicidal activity results from a mix of saponins. TSPs did not reduce the abundance of beneficial soil arthropods, nor did they control black cutworms or white grubs in treated turf. TSPs are an effective botanical vermicide that could be useful for selectively managing earthworm casts on closely mowed turfgrass. They might also be used to suppress earthworms in grassy strips alongside runways to reduce bird strike hazard at airports.

Response of Four Turfgrass Species to Ethofumesate

Annual bluegrass and roughstalk bluegrass are turfgrasses, but they can also be two of the most serious weed problems in highly maintained turfgrass. Ethofumesate has been used to control annual bluegrass; however, the results have been erratic, and ethofumesate is not widely utilized for annual bluegrass control in turfgrass. The objective of this research was to characterize the response of annual, roughstalk, and Kentucky bluegrasses and creeping bentgrass to a range of ethofumesate rates. Single applications of ethofumesate from 3.4 to 20.2 kg ai/ha were made to all four species during May of 1999 to 2001. All four species were injured from rates of ≥6.7 kg/ha. Roughstalk bluegrass was most injured by a single ethofumesate application. Percent roughstalk bluegrass control increased linearly with rate, and greater than 85% control was observed for rates of ≥16.8 kg/ha. In contrast, annual bluegrass showed almost no control, with rates ≤10.2 kg/ha, and the highest rate tested, 20.2 kg/ha, controlled only 47 to 62% of the annual bluegrass. Kentucky bluegrass was the least sensitive bluegrass species, with a maximum control of 3 to 15% from 20.2 kg/ha of ethofumesate. Creeping bentgrass was the least sensitive of the species tested, with low levels of control regardless of rate. During 3 yr of testing, maximum control of bentgrass from any rate was 4%. Single, high-rate applications of ethofumesate hold promise to control roughstalk bluegrass in creeping bentgrass turf. Sixteen Kentucky bluegrass cultivars used for low-cut athletic fields were evaluated for their tolerance to sequential ethofumesate applications during 1999 and 2002. The cultivars showed significant differences in ethofumesate tolerance, with ‘Moonlight’ and ‘America’ never showing any injury to sequential ethofumesate applications, while ‘Northstar’ and ‘Total Eclipse’ were severely injured.

Soil Gas, Temperature, Matric Potential, and Creeping Bentgrass Growth Response to Subsurface Air Movement on a Sand-based Golf Green

Creeping bentgrass (Agrostis palustris Huds.) is used on putting greens for its fine-leaf texture, consistent speed, smooth ball roll, and year-round color. In recent years bentgrass use has extended into the warmer climates of the southern United States. Being a C3 plant, bentgrass is not well adapted to extended hot and humid environmental conditions. Subsurface air movement systems are now commercially available that can transport air through the root zone to alter soil conditions and potentially improve bentgrass survival. This research investigated the effects of subsurface air movement on the composition of soil gases, matric potential, temperature, and growth response of a sand-based creeping bentgrass golf green. Treatments included: air movement direction (evacuate, inject, and no air) and duration of air movement (0400-0600 hr, 1000-1800 hr, and 24 hours). Treatment combinations were imposed for 13 days. Subsurface air movement reduced CO2 at the 9-cm depth to values &lt;0.0033 mol·mol-1 when evacuating or injecting air, depending upon duration. Soil matric potentials at a 9-cm depth were decreased by a maximum of 96% when evacuating air for 24-hour duration compared to no-air plots. Soil temperatures at 9 cm were decreased ≈1 to 1.5 °C when injecting air from 1000 to 1800 hr and 24-hour treatments and increased ≈0.75 °C when evacuating air from 1000 to 1800 hr. Subsurface air movement did not improve creeping bentgrass turf quality or rooting. Although not effective in improving the growth response of creeping bentgrass, subsurface air movement may be a useful tool to improve soil gas composition, reduce excess soil moisture, and potentially reduce soil temperature(s) of heat-stressed creeping bentgrass golf greens.

Postemergence Control of Annual Bluegrass (Poa annua spp. reptans) in Creeping Bentgrass (Agrostis stolonifera) Turf1

The postemergence herbicide ethofumesate and the plant growth regulator paclobutrazol were evaluated for annual bluegrass control in creeping bentgrass turf managed as golf fairways. Both products were applied under several different timing regimes relative to the time of the year. Paclobutrazol treatments provided significantly greater annual bluegrass control than ethofumesate. There were no differences between rates of paclobutrazol (0.28 and 0.14 kg ai/ha) when applied from spring through summer. Annual bluegrass control after spring and summer applications of paclobutrazol was 85% or more. Clipping weight data indicated that paclobutrazol suppressed growth in annual bluegrass longer than in creeping bentgrass. It was concluded that prolonged suppression of annual bluegrass by paclobutrazol resulted in creeping bentgrass dominance and subsequent annual bluegrass control. Additionally, applications of ethofumesate in autumn–winter, followed by paclobutrazol applied in spring–summer, provided significan...

Effect of Turfgrass on Soil Mobility and Dissipation of Cyproconazole

Previous studies of pesticide fate in turfgrass have found less mobility and more rapid dissipation compared with studies using the same pesticide applied to bare soil. Few direct comparisons of pesticide mobility and dissipation in turfgrass vs. bare soil have been conducted. The mobility and persistence of cyproconazole [α‐(4‐chlorophenyl)‐α‐(1‐cyclopropylethyl)‐1H‐1,2,4‐triazole‐1‐ethanol] on bare soil (Flanagan silt loam; fine, smectitic, mesic Aquertic, Argiudoll) and turf containing varying levels of organic matter was examined under field conditions. Twenty‐centimeter‐diameter polyvinyl chloride (PVC) cylinders were installed in either creeping bentgrass turf (Agrostis palustris Huds.), or in turf in where either 33, 67, or 100% of the thatch and plant material had been removed. Cyproconazole was applied at 403 g a.i. ha−1 on 15 July 1996 and 8 July 1997. Replicate sampling cylinders were removed 2 h after treatment (HAT) and 4, 8, 16, 32, 64, and 128 d after treatment (DAT). Cylinder cores were sectioned into depths and assayed for cyproconazole by gas chromatography. On all sampling days, increasing the amount of surface organic matter decreased the amount of cyproconazole in the 0‐ to 1‐, 1‐ to 3‐, 3‐ to 5‐, and 5‐ to 15‐cm core sections. The amount of cyproconazole detected in the soil under a full stand of turf at 4 and 32 DAT was 1 and 11%, respectively, of that detected in bare soil. Cyproconazole residues never exceeded 20 μg kg−1 in the 15‐ to 30‐cm core section of any treatment. The half‐life of cyproconazole decreased from 129 d in bare soil to 12 d in a full bentgrass turf. Cyproconazole movement below 5 cm in the soil was reduced with increasing amounts of turfgrass thatch, and as little as one‐third of a full stand of turf greatly decreased the half‐life of cyproconazole. Application of cyproconazole to turfgrass results in less mobility and more rapid dissipation than is typically reported in other agronomic crops.

Temporal Shade on Creeping Bentgrass Turf

Creeping bentgrass (Agrostis palustris Huds.) turf exposed to shade during morning hours may decline more readily than similar turf exposed to afternoon shade. This study compared the quality and physiological responses of creeping bentgrass turf exposed to morning shade with turf exposed to afternoon shade and evaluated responses of the same species exposed to varying shade densities during the same period. Semipermanent shade structures were placed on a creeping bentgrass range maintained at a 6.4‐mm height. Structures provided 6 h of morning shade or 6 h of afternoon shade during the summer solstice. Each structure was covered with either 80 or 100% shade cloth and replicated three times. Control treatments of full sun and perpetual shade were also included. Treated turf was evaluated monthly for color, density, root mass, pigment concentrations, and total nonstructural carbohydrates (TNC). Regardless of response tested, no significant variation was found between plots receiving morning shade and afternoon shade or between plots in 80 and 100% shade. Canopy temperature, in comparison with air temperature, was 7% greater in morning shade than in afternoon shade, but the relationship between canopy temperatures in full sun and shade did not change during the day. Perpetual shade caused a 38% decrease in color and a 33% decline in density but treatments receiving 6 h of shade did not vary from the full sun treatment. Concentrations of chlorophyll a (46%) and b (50%), neoxanthin (31%), violaxanthin (44%), lutein (34%) declined in perpetual shade compared with full sun. Violaxanthin concentration was influenced by photosynthetic photon flux, suggesting its potential use as a shade stress indicator.

Use of Multispectral Radiometry for Assessment of Rhizoctonia Blight in Creeping Bentgrass

ABSTRACT The ability to identify diseases early and quantify severity accurately is crucial in plant disease assessment and management. This study was conducted to assess changes in the spectral reflectance of sunlight from plots of creeping bentgrass during infection by Rhizoctonia solani, the cause of Rhizoctonia blight, and to evaluate multispectral radiometry as a tool to quantify Rhizoctonia blight severity. After inoculation of 6-year-old creeping bentgrass turf with R. solani anastomosis group 2-2, reflectance of sunlight from the foliar canopy was measured at light wavelengths of 460 nm (blue) to 810 nm (near infrared [NIR]), at 50-nm intervals. Visual estimates of disease severity and percentage of canopy reflectance were made daily throughout each of three epidemics of Rhizoctonia blight from the onset of visible symptoms until maximum disease severity was reached. In each experiment, linear regression analysis revealed a significant reduction in the percentage of NIR (760 and 810 nm) reflectance as disease severity increased. However, in the majority of analyses, regression models explained <50% of the variability between components. Multispectrum radiometry appears to function best when used to assess differences in disease severity at discrete points in time rather than over an entire epidemic.

Improved Biocontrol Efficacy of Trichoderma harzianum 1295-22 for Foliar Phases of Turf Diseases by Use of Spray Applications.

Trichoderma harzianum strain 1295-22 is an effective biocontrol agent for several fungal diseases. The efficacy of granule and spray applications of strain 1295-22 for control of Pythium root rot, brown patch, and dollar spot of creeping bentgrass was investigated. Spray applications of conidial suspensions (SA) of strain 1295-22 significantly reduced all three diseases of creeping bentgrass turf in both greenhouse and field experiments. Control was greatest when Triton X-100 at 0.1% was added to aqueous spray suspensions. When SA were applied weekly, the biocontrol treatments were equivalent to standard fungicides. Broadcast granule applications (GA) also significantly reduced foliar symptoms of Pythium root rot, dollar spot, and brown patch; turf quality also was enhanced. The populations of Trichoderma spp. in the root zone of a bentgrass putting green treated with SA or GA of strain 1295-22 increased 10- to 100-fold after treatment compared with untreated plots. However, strain 1295-22 was present at high levels on bentgrass leaves only following SA. Collectively, the results suggest that strain 1295-22 possesses both rhizosphere and phylloplane competence. The combination of broadcast applications of granules followed by spray applications of conidia reduced damage from both root and foliar diseases.

Nocturnal Activity and Movement of Black Cutworms (Lepidoptera: Noctuidae) and Response to Cultural Manipulations on Golf Course Putting Greens

Nocturnal activity, feeding behavior, and movement of black cutworms, Agrotis ipsilon (Hufnagel), and responses of larvae to cultural manipulations were evaluated on creeping bentgrass, Agrostis palustris Hudson, golf putting greens. Larvae were active throughout most of the night with the greatest activity between midnight and ≈1 h before sunrise. Small larvae (3rd and 4th instars) were active on the surface of putting greens, whereas large larvae (5th and 6th instars) fed mainly from burrows or tunnels in the putting green surface. Larval tracks in the dew averaged 8.8 ± 0.7 m, indicating that A. ipsilon can move considerable distances on putting greens in a single night. Many larval tracks originated from the peripheral area, suggesting that some larvae found on putting greens originate from higher-mowed turf surrounding the green. Contrary to the common belief of golf course superintendents, A. ipsilon larvae were not attracted to aerified over nonaerified turf. However, most larvae occupied aerification holes as burrows when such holes were available. Topdressing with 100% silicas and or a silica sand/peat moss mix did not affect survival of cutworms in creeping bentgrass turf cores. Nevertheless, larvae tended to avoid putting green surfaces topdressed with sand. Manipulating the timing of topdressing may be one method of reducing cutworm populations on putting greens.

Effect of Repeated Fungicide Applications on Creeping Bentgrass Turf

Though fungicides are regularly applied to creeping bentgrass (Agrostis palustris Huds.) turf throughout a growing season, little is known about possible non‐target effects of these applications on turfgrass growth and metabolism. The objective of this field study was to determine the effect of 3 yr of multiple applications of fungicides to ‘Penncross’ creeping bentgrass maintained under putting green conditions and on a native silt loam soil. Benomyl [methyl‐1‐(butylcarbamoyl)‐2‐benzimidazolecarbamate] at 3.05 kg ha−1, iprodione [3‐(3,5‐dichlorophenyl)‐N‐(1‐methylethyl)‐2,4‐dioxo‐1‐imidazolidinecarboximide] at 3.05 kg ha−1, and propiconazole [1‐(2‐(2,4‐dichlorophenyl)‐4‐propyl‐1,3‐dioxolan‐2‐ylmethyl)‐1H‐1,2,4‐triazole] at 0.84 kg ha−1 were applied weekly or alternated with chlorothalonil (tetrachloroisophthalonitrile) at 6.36 kg ha−1. Sixteen applications were made in each of 3 yr. Propiconazole applied weekly or alternated with chlorothalonil increased clipping weights, turned bentgrass dark green, and decreased visual quality throughout the study. Chlorothalonil, propiconazole, and benomyl reduced water‐soluble carbohydrate (WSC) concentrations of clippings during the study, this effect was most common in the heat of late summer. Benomyl applied weekly and chlorothalonil applied weekly or alternated with the other fungicides decreased earthworm activity. Propiconazole applied weekly or alternated with chlorothalonil increased damage from pink snow mold (Microdochium nivale Samuels and I. C. Hallett). Chlorothalonil applied weekly and alternated with the other fungicides increased rooting the last year of the study. Fungicides applied frequently did not have serious negative non‐target effects on Penncross creeping bentgrass.