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In recent years, rising competition for water coupled with new environmental regulations has exerted pressure on water allocations for turfgrass irrigation. In this article, we reviewed published scientific and industry evidence on the agronomic and environmental impacts of turfgrass irrigation using a robust systematic review methodology. Our focus was on the links between (i) irrigation management (amount and frequency), (ii) agronomic responses to irrigation (turf quality, growth rates and rooting) and (iii) environmental impacts (nitrogen leaching). Based on an initial screening of 653 studies and data extracted from 83 papers, our results show that in most cases, under moderate levels of deficit irrigation (50%–60% of actual evapotranspiration), turf quality can be maintained at an acceptable level but with lower water consumption compared to irrigating back to field capacity. Irrigation beyond field capacity was found to increase the risk of nutrient leaching. However, evidence also showed that the concentration and total loss of urn:x-wiley:09312250:media:jac12265:jac12265-math-0001 in leachate were influenced more by nitrogen (N) rates, soil characteristics, turfgrass species and turfgrass growth rates than by irrigation practices. Our analyses suggest that turfgrass irrigation should be scheduled to apply water at moderate levels of deficit irrigation, sufficient to maintain turfgrass quality but limited to promote a deep and extensive rooting system. The findings provide new insights and valuable evidence for both scientists and practitioners involved in turfgrass research and management.

Sammendrag

Plenarealer kan inngå som en integre1t del av byenes lokale overvannsdisponering (LOD). I denne rappmten ser vi på kunnskapsgrunnlaget rundt infiltrasjon og diskuterer konsekvenser for skjøtsel og flerbruk av plenarealene. Vi fant at målte mettede infiltrasjonsrater for norske plenarealer på sandig ejosrtdim oagt elert fote rl esiarnatdtbear sJeig1tgee rm i agjsseenrn. oSmamsnmitet np åm reudn dtetr 1r0en cgmu/tfotimrme iin vgeekns tvsiel sdoen hgeynd rmaueldis vkees eengetlnigs khaøpyeenree til undergrunnsmassene og oppbygningen av vekstmassene bestemme kapasiteten for overvannshåndtering til plenarealene og evt. problemer med uønsket oppstuving. Målrettet oppbygning av massene gir et sto1t potensiale for infiltrasjon av overvann ved etablering av grøntområder, men fordeling av overvann på eksisterende plen kan også gi store bidrag til LOD. pBorureks tarvu kptluerneanr eoagle urn tnilg oå vteh1avtacnhn, sshoåmn dluteftriinngg ovgi lt okprepvder eesns imnge.r…………...

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A number of factors such as low soil temperature, desiccation and thatch can be serious limiting factors for the successful reestablishment of golf greens following winter damages. The rate of germination and seedling root growth have important implications for competition between species on a golf green. This research project has shown that P. annua is a very competitive species, due to quicker germination at lower temperatures, especially compared to A. stolonifera and F. rubra ssp communtata. Root growth of P.annua was also significantly quicker than of the Agrostis species tested. Seedlings of Agrostis species and F.rubra ssp commutata that germinate in close proximity to P. annua seedlings stand a large chance of being choked out. In order to reduce competition with P.annua, early seeding should be avoided. In this study, no difference in turfgrass establishment wasobserved when seedlings were grown using soil water extracts or soil from an ice-encased green,compared to a control. However, further investigations regarding reestablishment following iceencasement are warrant, and should be investigated on older greens with a higher organic mattercontent. The results from the demonstration trials emphasize the importance of using a sowingtechnique that ensures proper seed – soil contact. This is of particular importance for theestablishment of turfgrass species on golf greens, due to the high risk of desiccation.

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Seed crops of white clover (Trifolium repens L.) are usually established with a cover crop. Provided sufficient light, white clover may compensate for low plant density by stoloniferous growth. Our objectives were (1) to compare spring barley or spring wheat used as cover crops for white clover and (2) to find the optimal seeding rate/row distance for white clover. Seven field trials were conducted in Southeast Norway from 2000 to 2003. Barley was seeded at 360 and 240 seeds m−2 and wheat at 525 and 350 seeds m−2. White clover was seeded perpendicularly to the cover crop at 400 seeds m−2/13 cm row distance or 200 seeds m−2/26 cm. Results showed that light penetration in spring and early summer was better in wheat than in barley. On average for seven trials, this resulted in 11% higher seed yield after establishment in wheat than in barley. The 33% reduction in cover crop seeding rate had no effect on white clover seed yield for any of the cover crops. Reducing the seeding rate/doubling the row distance of white clover had no effect on seed yield but resulted in slightly earlier maturation of the seed crop.

Sammendrag

Bladfaks er et varig og tørkesterkt fôrgras med kraftig utløperdanning. Viktige artskjennetegn er blad som er rullet i knoppleie, bladslire som er tynt behåret og lukket nesten helt opp til kragen, og et karakteristisk W-merke i bladplatene. Bladfaks er naturlig tilpasset kontinentale områder med kalde vintre og varme somre, så som Russland, Ukraina og prærie-områdene i USA og Canada. I Norge dyrkes bladfaks først og fremst i fjell- og dalbygdene på Østlandet, ikke minst i de tørre områdene i øvre Gudbrandsdalen / Ottadalen. Men på sandjord er bladfaks populær også i andre landsdeler, for eksempel i Nordland og indre fjordstrøk på Vestlandet.

Sammendrag

Engrapp (Poa pratensis L.) er et flerårig, vintersterkt bladgras med god gjenvekstevne. Arten har underjordiske stengelutløpere (rhizomer) og danner dermed en tett og slitesterk grasbunn. Av denne grunn er engrapp en viktig komponent i frøblandinger til beite, ferdigplen, fotballbaner og andre grasarealer med mye slitasje. Engrapp er treg i etableringsfasen og tåler dårlig klipping under 2 cm, men den er hardfør og varig. Ved avbeiting på et tidlig stadium er den en ypperlig fôrplante.

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Rødkløver en den viktigste engbelgveksten i Norge. Sammenlikna med grasartene gir rødkløveren et smakelig fôr med høyt protein- og mineralinnhold. Rødkløverfrø utgjør derfor 10-20 vektprosent av de fleste frøblandinger til slåtteng og kombinert eng/beite. Rødkløveren er imidlertid ei lite varig plante, og særlig ved sterk nitrogengjødsling og kraftig beiting vil den gå ut av enga etter et par år.

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Invasion of annual bluegrass (Poa annua L.) is a major concern on red fescue (Festuca rubra L.) putting greens. Our objective was to determine the effect of three seasonal fertilizer distribution treatments on red fescue turf quality and annual bluegrass encroachment. The experiment was conducted over 2 yr on a USGA-specified putting green at NIBIO Turfgrass Research Center Landvik, Norway (58° N). A complete liquid fertilizer was applied weekly for an annual nitrogen input of 11 g m−2 in all treatments. In the FLAT rate treatment, the weekly fertilizer rate was 0.45 g N m−2 wk−1 from 5 May to 28 September. The FALL+ treatment received 0.68 g N m−2 wk−1 from 11 August to 28 September and 0.23 g N m−2 wk−1 from 5 May to 21 June, whereas the SPRING+ treatment was the opposite. The SPRING+ fertilization resulted in significantly better turf quality and significantly less annual bluegrass than the two other treatments in the second year of the study. The FALL+ fertilization gave higher quality ratings in the fall and early spring, but this effect came at the expense of more annual bluegrass. In conclusion, we recommend a fertilizer regime with the highest input from early May until midsummer to produce red fescue putting greens with the highest possible turfgrass quality and minimal encroachment by annual bluegrass.

Sammendrag

Turfgrass grow-in on sand-based putting greens usually incurs a high risk for nitrogen (N) leakage. Our objective was to evaluate how substitution of a standard mineral fertilizer with an amino-acid-based fertilizer affects creeping bentgrass (Agrostis stolonifera L.) establishment rate and the concentration of nitrate and total N in drainage water. The experiment was conducted from 19 May to 26 July 2016 in the United States Golf Association green field lysimeter facility at Landvik, Norway. The liquid fertilizers arGrow Turf (70% of N as arginine and 30% as lysine) and Wallco (60% of N as nitrate and 40% as ammonium) were applied at ∼2-wk intervals at the two rates of 1.5 or 3.0 g N m−2 application−1. Results showed significantly faster grow-in on plots receiving amino-acid-based fertilizer than on plots receiving mineral fertilizers; the average turfgrass coverage 26 d after the first fertilization was 75 and 36%, respectively. In parallel with this, the average concentration of nitrate and total N in drainage water, as well as the total N loss, were all reduced by 40 to 45%. Arginine and lysine at 1.5 g N m−2 gave faster grow-in than Wallco at 3.0 g N m−2 and was the only treatment in which the drainage water complied with EU’s requirements for maximum concentration of nitrate in drinking water.

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Research concerning the cultural practice of golf course fairways is important because legislation on pesticide reduction in Europe and North America may potentially cause serious weed problems. Establishing a strong, competitive turfgrass sward may aid in reducing the invasion of broadleaved weeds and Poa annua L. The objective of this research was to determine changes in the grass species composition and weed occurrence of in-use fairway turfs after repeated overseeding of three grass species separately: Lolium perenne L., Festuca rubra L., and Poa pratensis L., all at rates 300 kg ha−1. Overseeding was conducted with a disc seeder, alone or in combination with extra fertilizer (50 kg N + 34 kg P ha−1) in either May or September on three Danish golf courses from 2011 to 2013. Results showed no increase in the population of F. rubra or P. pratensis after 3 yr of overseeding. Lolium perenne was successfully introduced when seeded in autumn and when extra fertilizer was added immediately after overseeding. None of the overseeding treatments reduced the occurrence of P. annua, Taraxacum officinale F.H. Wigg., Bellis perennis L., or Trifolium repens L. The results are discussed in relation to the fact that the fairways were unirrigated and that they were open to play after overseeding.

Sammendrag

Frø fra stedegne grasarter som vokser i den norske fjellheimen vil gi et mer naturlig og varig plantebestand på hyttetak, rundt hyttene, i veiskråninger og ved revegetering av andre sår i naturen.

Sammendrag

Både til fôrproduksjon og i plen er flerårig (engelsk) raigras (Lolium perenne) den mest brukte grasarten i Europa. Rask etablering, store tørrstoffavlinger, gode gjenvekstevne og fremragende forkvalitet er viktige årsaker til at denne grasarten har blitt så populær. De viktigste ulempene er at raigraset er følsomt for tørke og lite vinterherdig. Flerårig raigras egner seg derfor best i kystnære områder med lang vekstsesong, mye nedbør og milde vintre.

Sammendrag

Kvitkløver (Trifolium repens L.) er en næringsrik og smakfull engbelgvekst. I vill tilstand er arten utbredt over hele Europa, men den gjør mest av seg i nedbørrike og kystnære områder. Innafor kvitkløver er det stor variasjon i voksemåte og varighet - fra storblada, opprette og nærmest ettårige typer i Middelhavsområdet, til småblada, krypende og flerårige typer i Nord-Skandinavia. Som kulturplante er kvitkløver mest brukt i frøblandinger til beite, men den er også aktuell som grønngjødslingsvekst, i frøblandinger til plen og grøntanlegg, og i blandinger til varig grasmark som skal brukes både til slått og beite.

Sammendrag

Rødsvingel (Festuca rubra L.) er et bladgras med god gjenvekstevne. Sitt største bruksområde har arten i grøntanlegg, både kortklipte golfgreener, plener og grasbakkearealer (veiskråninger og lignende). Sammenlikna med andre grøntanleggsgras har rødsvingel lite nærings- og vatningsbehov og stor skyggetoleranse. I Norge inngår rødsvingel også i noen få frøblandinger til varig eng og beite, særlig i områder med vanskelige overvintringsforhold. Rødsvingel har imidlertid dårlig smakelighet, og verdien som fôrplante er derfor begrenset.

Sammendrag

Sauesvingel (Festuca ovina L.) en svaktvoksende og typisk tuedannende grasart. Sauesvingel er viltvoksende over mesteparten av innlands-Norge, og den er mest framtredende i tørkeutsatte og skrinne områder i fjellet, der andre grasarter ikke klarer seg. Sauesvingel har grunt rotsystem, trådsmale blad, liten tørrstoffproduksjon og dårlig smakelighet. Dens viktigste bruksområdet er derfor ikke som fôr- eller beiteplante, men til revegetering av vegkanter og anleggsområder i fjellet. Et annet spesialområde kan være frø til hyttetomter og hyttetak.

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Growing substrates, fertilizer inputs, and irrigation are important factors for grow-in of sand-based putting greens. The research reported here was triggered by grow-in problems encountered in 2015 after replacing garden compost with Sphagnum peat in the rootzone on a sand-based green at the NIBIO Turfgrass Research Center, Norway. A pot trial was conducted with the same type of sand amended with: (i) 20% (v/v) garden compost, (ii) 10% (v/v) Sphagnum peat, (iii) equal volumes of (i) and (ii), (iv) 10% (v/v) Sphagnum peat plus lime (200 g CaCO3 m−2), and (v) 10% (v/v) Sphagnum peat plus phosphoric acid, 5 g P m−2. The amendments were tested with or without preplant application of chicken manure (5 g N and 2.5 g P m−2) and at the two irrigation rates: 3 and 12 mm d−1. The pots were seeded with creeping bentgrass (Agrostis stolonifera L.), and turfgrass coverage and clipping yields were recorded for 5 wk after seeding. Turfgrass coverage developed significantly faster and clipping yields were significantly higher after amendment with compost than after amendment with peat or peat plus lime. Incorporation of chicken manure did not enhance grow-in on substrates containing full or half rates of compost but improved grow-in on peat, especially when combined with phosphoric acid. Excessive irrigation had no impact on turfgrass coverage but reduced clipping yields on substrates containing compost, compost plus peat, or peat plus phosphoric acid. We conclude that the grow-in problems encountered in 2015 were most likely due to inadequate quality of the Sphagnum peat.

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Conversion from annual bluegrass or bentgrasses to red fescue could be an efficient way to minimise water use on golf greens. Our objective was to investigate the influ- ences of four irrigation strategies on red fescue water use efficiency, turf quality, growth rate and resistance to annual bluegrass and moss invasion. The trial was car- ried out from August 2013 to August 2015 on a green established according to USGA recommendations under a rainout shelter at Landvik, Norway (58 ° N). On average for 2 years, irrigation to field capacity once per week (FC 1) and deficit irrigation to 60% of FC three times per week (DEF 3) reduced the water consumption by 49% and 72% relative to irrigation to FC three times per week (FC 3). Both DEF 3 and FC 1 retained acceptable turf quality and reduced annual bluegrass in the second year by about one-third. Better control of annual bluegrass was obtained with deficit irrigation to 60% of FC once per week (DEF 1), but this treatment did not produce acceptable turf quality. Compared with FC 3, DEF 3, FC 1 and DEF 1 gave harder surfaces and reduced the moss invasion in the second year by 66%, 90% and 93%, respectively. Irrigation effects on root development and thatch organic matter after 2 years were not significant, although the thatch layer depth was 3 – 4 mm greater in FC 1 than in the other treatments. In conclusion, DEF 3 and FC 1 are both effective irrigation strategies for managing red fescue greens with less water use.

Sammendrag

Ice encasement (IE) is the most economically important winter stress in Scandinavia; however, little is known about the IE tolerance of different turfgrass species and subspecies except that creeping bentgrass (Agrostis stolonifera L.) is more tolerant than annual bluegrass (Poa annua L.). The objective of this study was to assess the impact of IE and two protective covers (plastic and plastic over a 10-mm woven mat) on the winter survival of six cool-season turfgrasses commonly used on golf greens. The experiment was conducted on a sand-based green at Apelsvoll, Norway (60°42′ N, 10°51′ E) during the winters of 2011–2012 and 2012–2013. Turfgrass samples (8 cm in diameter, 10 cm deep) were removed from the plots at the time of cover installation and throughout the winter. The samples were potted and percent live turfgrass cover assessed after 21 d of regrowth in a growth chamber. Percent turfgrass cover, percent disease, and turfgrass quality were also registered in the field plots in spring. Results indicated that velvet bentgrass (Agrostis canina L.) had superior tolerance to IE, surviving for 98 and 119 d of IE during the winters of 2011–2012 and 2012–2013, respectively. The order of IE tolerance in 2012–2013 was: velvet bentgrass > creeping bentgrass > Chewing’s fescue (Festuca. rubra L. ssp. commutata), slender creeping red fescue (F. rubra L. ssp. litoralis) ≥ colonial bentgrass (A. capillaris) > annual bluegrass. Colonial bentgrass responded negatively to both protective covers in 2012 due to the development of Microdocium nivale. None of the species benefited from the plastic cover alone, compared with natural snow conditions. Annual bluegrass was the only species that benefited from plastic over a woven mat.

Sammendrag

Ice encasement (IE) is the most economically important winter stress in Scandinavia; however, little is known about the IE tolerance of different turfgrass species and subspecies except that creeping bentgrass (Agrostis stolonifera L.) is more tolerant than annual bluegrass (Poa annua L.). The objective of this study was to assess the impact of IE and two protective covers (plastic and plastic over a 10-mm woven mat) on the winter survival of six cool-season turfgrasses commonly used on golf greens. The experiment was conducted on a sand-based green at Apelsvoll, Norway (60°42′ N, 10°51′ E) during the winters of 2011–2012 and 2012–2013. Turfgrass samples (8 cm in diameter, 10 cm deep) were removed from the plots at the time of cover installation and throughout the winter. The samples were potted and percent live turfgrass cover assessed after 21 d of regrowth in a growth chamber. Percent turfgrass cover, percent disease, and turfgrass quality were also registered in the field plots in spring. Results indicated that velvet bentgrass (Agrostis canina L.) had superior tolerance to IE, surviving for 98 and 119 d of IE during the winters of 2011–2012 and 2012–2013, respectively. The order of IE tolerance in 2012–2013 was: velvet bentgrass > creeping bentgrass > Chewing’s fescue (Festuca. rubra L. ssp. commutata), slender creeping red fescue (F. rubra L. ssp. litoralis) ≥ colonial bentgrass (A. capillaris) > annual bluegrass. Colonial bentgrass responded negatively to both protective covers in 2012 due to the development of Microdocium nivale. None of the species benefited from the plastic cover alone, compared with natural snow conditions. Annual bluegrass was the only species that benefited from plastic over a woven mat.

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There has long been a claim that winter injuries of grass are a significant economic burden for golf courses in the Nordic countries. To confirm this claim, in 2015 the Norwegian Institute of Bioeconomy Research and the Norwegian Golf Federation, with support of the Scandinavian Turfgrass and Environment Research Foundation, conducted a net-based survey about winter injury in the five Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden). This comprehensive survey showed that total costs of repair of winter-injured greens and fairways together with lost revenue on golf courses in the Nordic countries can be at least €14 million. In a year with significant winter injuries, the average cost to repair the turf was between €3000 and €12,000 on 88% of the courses. The revenue loss after a winter with considerable injuries was less than €6000 at 50% of the courses, and 25% of the courses reported a loss between €6000 and €12,000 for these years. The causes of winter injuries varied depending on geography and grass species used on the greens. Biotic factors played a major role in the southern part of Scandinavia, and ice and water injuries were most devastating north of 60°N. This paper summarizes some of the answers from the respondents, including information about the dominating grass species on Nordic golf greens.

Sammendrag

Både ved økologisk og konvensjonell dyrking er engsvingel, nest etter timotei, det viktigste fôrgraset i Norge. I 2016 ble det godkjent rundt 43 tonn økologisk engsvingelfrø. Regelverket for økologisk landbruk krever at det skal brukes økologisk dyrka såvare så sant dette kan skaffes. I Norge har vi økologisk frøavl av engsvingelsortene Fure, Norild og SW Minto. Fure brukes i lavlandet i hele Sør-Norge, spesielt på Vestlandet. Norild er hovedsort for Nord-Norge, Trøndelag, fjellbygdene og innlandsstrøka på Østlandet. SW Minto (godkjent 2008) er en svensk sort (Svalöf Weibull AB) som er mye lik Fure, men med tendens til bedre overvintring og varighet enn Fure, spesielt i Sør-Norge. Frøavlen må foregå på bruk uten floghavre.

Sammendrag

Rødkløver en den viktigste engbelgveksten i Norge. På grunn av stor evne til nitrogenfiksering, høyt protein- og mineralinnhold og gunstig virkning på jordstrukturen inngår arten i alle engfrøblandinger for økologisk landbruk. Norske regelverk for økologisk produksjon(Mattilsynet / DEBIO) krever at det ved all økologisk dyrking skal bruke økologisk såvare så sant dette kan skaffes og sortene er egna for lokaliteten.

Sammendrag

Både ved økologisk og konvensjonell dyrking er timotei den viktigste grasarten i Norge. Regelverket for økologisk landbruk krever at det skal brukes økologisk dyrka såvare så sant dette kan skaffes. Timoteisortene som brukes er de samme i økologisk og konvensjonell grasdyrking. Lidar anbefales for Nord-Norge og høyereliggende strøk i Sør-Norge. De har god vinterherdighet, tidlig vekstavslutning om høsten og meget gode frøavls-egenskaper. Grindstad er enerådende som lavlandsort. Sorten har utmerket seg i sortsforsøkene, spesielt på grunn av sin store gjenvekstevne.

Sammendrag

Engkvein (Agrostis capillaris L.; tidligere også benevnt Agrostis tenuis Sibth.) er en nøysom grasart med svak utløperdanning, rulla bladslire og lyse, jamt avsmalende blad med tydelige karstrenger. I eng og beite kommer engkvein ofte inn når andre grasarter går ut av enga, for eksempel på grunn av mangel på kalking eller gjødsling. Av denne grunn inngår engkvein i noen frøblandinger til ekstensiv eng og beite, men ellers tilsier både tørrstoffavling og fôrkvalitet at engkvein er lite egna som sådd jordbruksvekst. Langt viktigere er den i frøblandinger til grøntanlegg, alt fra kortklipt golfgreen til ekstensive veiskråninger. På slike steder sås engkvein ofte i blanding med rødsvingel, men på grunn av frøstørrelsen inngår det sjelden mer enn 10 vektprosent engkvein i blandingene. Etter skyting vil engkvein ofte sette et vakkert og mørkerødt preg på kulturlandskapet. Dette gjenspeiles av det svenske navnet ’rödven’. I Danmark kalles engkvein ’almindelig hvene’.

Sammendrag

Microdochium nivale (Fries) Samuels & Hallett is an important turfgrass pathogen on golf courses. Our objective was to evaluate Gliocladium catenulatum Gilman & Abbott and/or Streptomyces species for biological control of M. nivale on golf greens. The microbial agents were tested relative to fungicides and an untreated control in vitro and in five field trials from 2011 to 2014. G. catenulatum (Turf G+/WPG, Verdera OY, Finland) was applied from October to December and in March–April, while Streptomyces species (Turf S+/WPS, same manufacturer) was applied from May to October, both at four week intervals. In vitro, Streptomyces species suppressed the growth of M. nivale at 6 and 16°C, while G. catenulatum suppressed growth of M. nivale at 16°C only. In contrast, neither product, nor their combination, had any consistent effect in the field trials. A statistically significant reduction in Microdochium patch (from 3 to 2% of plot area) was seen in a trial on a green dominated by Festuca rubra L., but this reduction was deemed to be of little practical interest to the greenkeeper. Despite multiple applications over 3 yr to build up an antagonistic microflora, only fungicides reduced M. nivale significantly on greens dominated by Poa annua L. or Agrostis capillaris L., which generally had more disease. In conclusion, this research showed no potential of G. catenulatum or Streptomyces species to replace fungicides for control of M. nivale on northern-latitude golf greens.

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Red fescue (RF, Festuca rubra L.) is used on golf putting greens in the Nordic region due to its high disease resistance and low requirements for nitrogen (N) and water, but low density and growth rate makes RF susceptible to annual bluegrass (AB, Poa annua L.) invasion. Putting greens seeded with RF + bentgrass (Agrostis sp.) may be more competitive with AB but also have different playing characteristics. Our objective was to compare RF, RF + colonial bentgrass (CB, Agrostis capillaris L.), and RF + velvet bentgrass (VB, Agrostis canina L.) putting greens at two mowing heights (4.0 or 5.5 mm), three N rates (5, 10, or 15 g N m−2 yr−1), and three phosphorus (P)–arbuscular mycorrhizal fungi treatments (0 and 1.8 g P m−2yr−1 without inoculation and 0 g P m−2yr−1 with inoculation). The four-factorial experiment was conducted in 2011 and 2012 at Landvik, Norway. Red fescue provided lower visual quality and density and less competition against AB than RF + bentgrass combinations. Increasing the N rate from 5 to 15 g N m−2yr−1 increased the proportion of bentgrass tillers from 53 to 64% in RF + CB and from 86 to 92% in RF + VB. Surface hardness increased in the order RF + VB < RF + CB < RF turfs. Ballroll distance decreased with increasing N rate and was longer with RF and RF + VB than with RF + CB. The main effects of N and mowing height on AB invasion were not significant, but lower mowing increased AB competition in RF. Mycorrhiza colonization of roots was not significantly affected by any practice, and neither P nor arbuscular mycorrhizal fungi influenced the competition against AB.

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Satisfactory seed yield of red clover (Trifolium pratense L.) cultivars is crucial for the availability of seeds on the market. Many breeders and researchers have used seed yield components to measure, compare, and explain differences in seed yield between diploid and tetraploid red clover cultivars and populations; however, the relative importance of each component varies between studies. In 2011 and 2012, single-plant trials with several tetraploid and one diploid red clover cultivar were established at the Norwegian plant breeding station at Bjørke. The goal was to study the impact of different seed-yield components on the seed yield of tetraploid plants. Seed weight per flower head was the seed-yield component that correlated best with the seed yield plant−1 (r = 0.91 and r = 0.68 in 2011 and 2012, respectively). Path coefficient analysis has also shown that the seed weight per flower head had the highest direct impact on seed yield plant−1 (direct path coefficients were 0.867 and 0.783 in 2011 and 2012, respectively). In comparison, the direct path coefficients for calculated number of flower heads, which was previously highlighted as the most important seed-yield component, were lower and more variable (0.739 and 0.392 in 2011 and 2012, respectively). Since previously seed yield per flower head was also identified as the most important seed-yield component in dense plant canopy, this component might have the potential to select for improved seed yield of new cultivars based on single plants. However, further studies are required to confirm this conclusion.

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While tetraploid plants of red clover are taller, have thicker stems, and have broader leaves that altogether result in a higher forage yield compared to diploids, they generally have substantially lower seed yields than diploid plants. Tetraploid red clover can be induced chemically by colchicine or nitrous oxide (N2O) and sexually by union of unreduced gametes. The average seed yield of tetraploid red clover in Norway is 60% of the diploid yield, while in Sweden it is 75%. One objective of this paper was to examine whether there is a difference in seed yield among chromosome doubled tetraploids and crossed tetraploids. A second objective was to investigate differences in seed yield and seed yield components in Norwegian and Swedish tetraploid populations. The third objective was to study which yield component most correlates with the seed yield per hectare. Seed production experiments were established at Landvik and Bjørke in Norway and Svalöv and Lännäs in Sweden. Populations made by crossings of tetraploids gave significantly greater yield (p < 0.001) compared to populations that were made by chromosome doubling. On average, Norwegian and Swedish varieties had equal yields in both experimental years. Norwegian and Swedish varieties differed mostly in earliness traits. Swedish populations began flowering on average 4 d earlier than Norwegian populations. Genotypic correlations showed that seed yield per flower head was the component with the highest correlation (r = 0.956 and r = 0.977) with yield per hectare in both experimental fields. Results from the second experimental year indicate a trend towards improved seed yield after several cycles of recurrent selection for higher seed yield per flower head.

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Sammendrag

This report presents results from a project testing Turf G+/WPG (fungal products containing Gliocladium catenulatum) and Turf S+/WPS (bacterial products containing Streptomyces spp.), both from Interagro BIOS AB, and Vacciplant (seaweed product containing laminarine) from Nordisk Alkali AB, for the control of Microdochium nivale and other diseases on golf greens. Five field trials were carried out in Denmark, Sweden and Norway from October 2011 to September 2014, and Turf G+/WPG and Turf S+ were tested also in vitro. None of the test-products gave any consistent disease control in the field trials. A significant reduction in Microdochium nivale from 3 % of plot area on untreated plots to 2 % on treated plots was seen in one trial, but this was considered to be of little practical relevance. In all other trials with more severe attacks of Microdochium nivale, only the fungicide control treatment showed a significant reduction in disease compared with the untreated control. On average for all field trials over three years, the higher rate of Vacciplant, the combination of Turf G+/WPG and Turf S+/WPS, and the fungicide treatment gave, in turn, 22, 24 and 87 % less microdochium patch in the fall, but among these, only the effect of fungicide was significant. The effects of the biological products on pink or gray (Typhula incarnata) snow mold after snow melt were even smaller. In the in vitro trials, Turf S+ provided good control of Microdochium nivale at 6 and 16 ̊C, but Turf G+/WPG was effective only at the higher temperature. However, since these results could not be repeated under field conditions, we have to conclude that none of the test products represent any real alternative to fungicides for control of M. nivale or other diseases on Scandinavian golf courses.

Sammendrag

Syngenta’s GREENCAST model was used to predict timing of fungicide application against microdochium patch and pink snow mold caused by Microdochium nivale on an experimental golf green with annual bluegrass (Poa annua) at Bioforsk Landvik, Southern Norway from 5 Oct. 2012 until 1 June 2013. From 5 Oct. until snow covered the green on 2 Dec. 2012, application of the fungicides Headway (azoxystrobin + propiconazole) or Medallion (fludioxonil) only at GREENCAST high risk warnings resulted in equal control of microdohium patch with one less fungicide application than prophylactic application every third week, application at first sign of disease or application at GREENCAST medium risk warnings. The consequences for pinks snow mold in spring could not be evaluated as the turf was killed by the combination of ice encasement and low freezing temperatures during winter.