Rapid Conversion of the Golf Course Putting Greens to Glyphosate-resistant Creeping Bentgrass

A genetically transformed creeping bentgrass cultivar that is resistant to the nonselective herbicide glyphosate has been developed. To date, glyphosate-resistant creeping bentgrass is not commercially available, but its use could ease weed control and improve overall quality of the putting surface. This innovation presents golf course superintendents with the opportunity to convert existing putting greens to glyphosate-resistant creeping bentgrass. To minimize disruption of golf play, methods that speed conversion of putting greens are needed. The objectives of this experiment were to evaluate how seeding date, mowing height, and nitrogen (N) fertility level affect conversion speed of established putting greens to glyphosate-resistant creeping bentgrass

Determining the Factors Affecting the Natural Occurrence of Entomopathogenic Nematodes in Turfgrass: A Principal Components Analysis

We conducted a study to determine the relationship between turfgrass management intensity and natural occurrence of entomopathogenic nematodes (EPNs) on golf courses in Ohio. 159 soil samples were collected from putting greens, fairways and rough areas – three distinct surfaces that are managed differently. EPNs were recovered from soil samples using the insect baiting technique. Soil samples were also analyzed for texture, organic matter, pH, phosphorus, calcium, magnesium and potassium. Principal components and correlation estimates were used to determine possible predictors of nematode occurrence in turfgrass. We found that surface type and soil texture were important factors in predicting nematode occurrence. Putting greens differed significantly from fairways and rough areas in the number of EPN-positive sites. EPNs were recovered from 42.9% of the fairways and 57.1% of the rough areas, but not from putting greens. Putting greens also differed significantly from fairways and rough areas in organic matter, pH, calcium and phosphorus. The fairways and rough areas did not however differ in EPN-positive sites and soil parameters. Presence of EPNs significantly correlated with sand, silt, phosphorus, organic matter and magnesium, but not with clay, pH, calcium or potassium. The nematode species were identified as Heterorhabditis bacteriophora, Steinernema carpocapsae, and S. glaseri. These results suggests that EPNs are more likely to occur in less intensively managed sites that receive fewer inputs, and have relatively high sand, low pH, and moderate phosphorus and magnesium contentThe Ohio State University/OARD

Anthracnose of bentgrass and annual bluegrass putting greens

Kennelly, Megan, Anthracnose of Bentgrass and Annual Bluegrass Putting Greens, Manhattan, Kansas, Kansas State University, July 2008

Rapid conversion of golf course turf to glyphosate-resistant creeping bentgrass

Creeping bentgrass (Agrostis stolonifera L.) is grown on golf course putting greens and its use as fairway turf is becoming more common. Creeping bentgrass cultivars tolerant to the herbicide glyphosate [N-(phosphonomethyl)glycine] have recently been developed. The ability to control weeds by the application of a nonselective herbicide, such as glyphosate, would ease overall turfgrass management. The conversion of existing putting greens and fairways to glyphosate-resistant creeping bentgrass is an option that many golf course superintendents are likely to consider. However, the conversion of existing turf to a more desirable species or cultivar is costly and would require the golf course to close for a considerable period of time. The objective of these field experiments was to speed the conversion of previously established putting greens and fairways to glyphosate-resistant creeping bentgrass. The best timing for glyphosate application to remove competition from existing grasses was researched on existing putting greens and fairways. Research was also conducted to study the effect of the following factors on conversion of existing putting greens to glyphosate-resistant creeping bentgrass: (i) seeding date, (ii) seeding rate, (iii) surface preparation method, (iv) mowing practices after seedling germination, and (v) N fertility. The best timing for glyphosate application to remove competition from existing turf was before seeding or shortly after seeding. Golf course putting green conversion to glyphosate-resistant creeping bentgrass was most rapid when seed was sown in late summer at 7.3 g m⁻². All surface preparation methods resulted in similar turf cover, but some methods were less labor-intensive and caused less disruption to the putting green surface. Putting green conversion was most rapid when seedlings were mowed for the first time at 6.4 mm and glyphosate-resistant creeping bentgrass was permitted to reach approximately 100% cover before lowering the mowing height at a rate of 0.76 mm wk⁻¹. No differences were observed between N fertility rates of 1.2 and 2.4 g m⁻² wk⁻¹. The results of these experiments suggest that successful conversion of golf course turf to glyphosate-resistant creeping bentgrass can occur with minimal interruption to golf play

Dose Responses of Silvery-thread Moss to Carfentrazone-ethyl

As compared with label recommendations, this research suggests that lower carfentrazone-ethyl rates and longer intervals may be effective for silvery- thread moss (STM; Bryum argenteum Hedw.) control in putting greens

Managing Stress Tolerance on Warm-Season Putting Greens in the Transition Zone

The use of warm-season putting greens in the transition zone has increased in recent years. Ultradwarf bermudagrass (Cynodon dactylon (L.) Pers x C. transvaalensis Burtt-Davy) is the most prevalent warm-season putting green selection in the transition zone, however, newly developed greens-type zoysiagrass (Zoysia spp.) cultivars represent another potential selection for golf courses. The two major limitations of warm-season grasses in the transition zone are a general lack of cold- and shade-tolerance. Protective covers are essential to protect ultradwarf bermudagrass putting greens in the winter months. Unfortunately, golf courses can still experience winterkill underneath protective covers. Two field trials were conducted with a goal of improving upon management strategies to improve the performance and survival of golf course putting greens under stress. Both trials were conducted on sand-based rootzones and were managed with cultural practices consistent with golf course putting greens found in the region. The first trial was conducted during the winters of 2019-20 and 2020-21 on a putting green consisting of four replicated whole plots of the three most prevalent ultradwarf bermudagrass cultivars. The goal of the trial was to improve upon cover strategies by supplementing protective covers with three air gap materials to provide additional insulation. Although materials such as straw and batting fabric provided moderate soil temperature gains compared to the cover alone, protective covers alone provided sufficient protection from winterkill during adverse weather conditions. Because of the high purchasing cost and labor requirement associated, wall to wall coverage of air gaps is not likely feasible. Where air gaps could be valuable is spot coverage of portions of putting greens that are especially vulnerable to winterkill (shade, north slopes, high traffic) and historically receive winterkill. The second trial was conducted during the growing seasons (June to October) of 2020 and 2021 on a putting green consisting of three replicated whole plots of ‘Lazer’ zoysiagrass (Zoysia matrella (L.) Merrill x Z. minima (Colenso) Zotov). Shade is a significant problem for golf course putting greens, so it is important to identify the precise amount of light is needed to maintain an acceptable putting green. Zoysiagrass is generally more shade tolerant than bermudagrass, however, ‘Lazer’ zoysiagrass has not been studied. The goal of this trial was to compare ‘Lazer’ zoysiagrass to an industry-standard putting green selection, ‘TifEagle’ bermudagrass, under varying levels of shade and management practices. Management practices included two mowing heights (2.5- and 3.2-mm) and with or without the treatment of the plant growth regulator, trinexapac-ethyl. The minimum daily light integral (DLI) was determined for both species and surface characteristics, including ball roll distance and surface firmness, were monitored. ‘Lazer’ zoysiagrass demonstrated superior shade-tolerance and had a minimum DLI requirement about 10 mol m-2 d-1 less than ‘TifEagle’. Surface firmness was greater for ‘Lazer’, while ‘TifEagle’ produced greater ball roll distance for most rating dates. However, both species consistently produced industry-standard ball roll distance. Results from this trial suggest that ‘Lazer’ zoysia can produce acceptable putting green conditions and is better adapted than ‘TifEagle’ to moderate shade conditions

Identification and Management of Moss and Phytopathogenic Algae Common on Creeping Bentgrass Putting Greens

Taxonomic traits were utilized to identify problematic moss species common to golf course putting greens. Three predominant species of moss were identified on two golf course putting greens located in East Tennessee. Bryum argenteum, Amblystegium serpens and Entodon seductrix were identified on creeping bentgrass putting greens. Green house studies were initiated to investigate all three moss species control with carfentrazone and mancozeb. Utilizing digital image analysis investigations concluded carfentrazone controlled all three moss species greater than mancozeb. Sequential carfentrazone applications controlled all three moss species greater than single applications. Moss recovery and regrowth was observed with carfentrazone. Field studies were initiated to evaluate Bryum argenteum control utilizing mancozeb, carfentrazone, and cultural practices. Cultural practices improved carfentrazone long term efficacy. Carfentrazone controlled Bryum argenteum greater than mancozeb. Similar Bryum argenteum control was observed with cultural practices alone and carfentrazone alone. Bryum argenteum recovery was observed with carfentrazone alone treatments. Mancozeb and non-treated plots increased in Bryum argenteum populations. A common problematic species of cyanobacteria was identified on three golf courses all located near Knoxville, TN. Isolates were identified genetically and compared to other similar isolates. The Tennessee cyanobacteria isolate had a 94 % match to a Phormidium murryi, a filamentous mat forming cyanobacteria. The isolate was then subjected to a ten day In vitro screen determining copper and zinc toxicity levels. Both copper and zinc killed the Tennessee cyanobacteria isolates at 3.2 micromole concentrations. Both zinc and copper at 0.6 micromole concentrations increased the Tennessee cyanobacteria isolates growth when compared to the non-treated

Tolerance of Kentucky Bluegrass to Mesotrione

Creeping bentgrass (Agrostis stolonifera L.) is a stoloniferous, cool-season perennial grass used predominately on golf course putting greens in temperate regions of the United States. Its use on golf course fairways is increasing steadily as new cultivars possess improved shoot density and disease tolerance. However, due to the aggressive growth habit of bentgrass, it often spreads into surrounding areas of Kentucky bluegrass (Poa pratensis L.) forming unsightly, scattered patches

Evaluation of Off-Type Grasses in Interspecific Hybrid Bermudagrass [\u3ci\u3eCynodon dactylon\u3c/i\u3e (L.) Pers. x \u3ci\u3eC. transvaalensis\u3c/i\u3e Burtt-Davy] Putting Greens

The economic impact of the golf industry in the United States (U.S.) in 2011 was estimated to be $176.8 billion. Interspecific hybrid bermudagrasses [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] are some of the most widely utilized grasses on golf courses throughout tropical, subtropical, and temperate climates. In 2007, bermudagrass was grown on 80% of putting green acreage in the southern U.S. ‘Tifgreen’ and ‘Tifdwarf’ were two of the first widely established cultivars on putting greens, but their genetic instability led to the occurrence of phenotypically different off-type (OT) grasses. Several OT grasses were selected and released as cultivars such as ‘Champion’, ‘MiniVerde’, and ‘TifEagle’. These cultivars can also be genetically unstable and OT grasses can occur in putting greens. The objectives of this research were to genetically and phenotypically characterize OT grasses and evaluate their responses to nitrogen (N) and trinexapac-ethyl (TE) applications. Off-type and desirable bermudagrass samples were collected from Champion, MiniVerde, and TifEagle golf course putting greens in 2013 and 2014. Grasses were genetically evaluated using genotyping-by-sequencing (GBS), which determined that 11% were genetically divergent from standard cultivars. Off-types were phenotypically characterized using morphology and samples clustered into three distinct morphological groups that varied in internode length and leaf length. The response of OT grasses and cultivars to six N and eight TE treatments was evaluated by measuring clippings 7, 14, 21, and 28 days after initial treatment (DAIT). The least three N rates decreased weekly clipping production 18 to 29% [percent], whereas the greatest three rates sustained growth. We observed that peak growth regulation occurred 21 DAIT for the majority of TE rates tested where clipping weights decreased 18 to 35% from 7 to 21 DAIT. We also observed a period of increased clipping production 18 to 47% from 21 to 28 DAIT for all grasses tested. It is important to maintain consistent growth among phenotypically different grasses in order to minimize any competitive growth advantage an OT grass may possess over a desirable cultivar in a golf course putting green