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Abstract

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.

Abstract

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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Abstract

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.

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Abstract

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.

Abstract

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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Abstract

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.

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Abstract

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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Abstract

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.

Abstract

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.

Abstract

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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Abstract

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.

Abstract

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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Abstract

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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Abstract

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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Abstract

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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Abstract

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.

Abstract

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.

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Abstract

This progress report presents preliminary results from a project providing data for potential registration of Turf S+ (bacterial product containing Streptomyces) and Turf G+/WPG (fungal product containing Gliocladium catenulatum), 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. Field trials with all three products are carried out on greens in Denmark, Sweden and Norway from 2011 to 2014, and Turf S+ og Turf G+/WPG are also tested in vitro. Half way through the project, none of the test-products have shown any consistent control of M. nivale or any other disease. In the trials at Bioforsk Landvik and Arendal GK, Norway, there was little attack of M. nivale and no significant effect of any treatment, while in the trials at Rungsted GC, Denmark and Kävlinge GC, Sweden, there were massive attacks, but a significant reduction in disease only in the fungicide control treatments. The fifth trial, at Sydsjælland GC, Denmark, had more healthy turf just before snow cover in late November 2012 on plots that had been sprayed the test products, especially with Turf S+ or Vacciplant than on unsprayed control plots, although the turf quality was not as good as in the fungicide control treatment. The first in vitro trial with the microbial agents suggested better effect of both G. catenulatum and Streptomyces sp. on M. nivale at 16 than at 6°C. Possible implications of this for the protocol will be discussed with the manufacturer. The experimental work continues until the summer of 2014.

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Abstract

Experiments were set up over two winter seasons on golf greens i the Nordic countries. Two mowing heights in the autumn and one late application of 0.2 kg N /100 m2 were examined for effects on winter survival and turf performance in the spring. There were small effects from mowing height, but partly significant positive effects of fertilization. The results form annual meadow grass (Poa annua) were not consistent, but red fescue (Festuca rubra), creeping bentgrass (Agrostis stolonifera) and velvet bent grass (A.canina) accorded.

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Abstract

This is a progress report from the second experimental year of the project ‘VELVET GREEN - Winter hardiness and management of velvet bentgrass (Agrostis canina) on putting greens in northern environments’. The report is divided into four main chapters, the first giving results from evaluation of winter hardiness of velvet bentgrass under controlled conditions, the second describing experimental layout and preliminary results from two field trials with fertilizer levels, thatch control methods and topdressing levels; the third describing experimental layout and preliminary results from a lysimeter study on irrigation stategies for velvet bentgrass on greens varying in rootzone composition; and the fourth describing a supplemental experiment evaluating the biological product ‘Thatch-less’ for thatch decomposition.

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Abstract

This is a report from the first experimental year of the project ‘VELVET GREEN - Winter hardiness and management of velvet bentgrass (Agrostis canina) on putting greens in northern environments’. The report is divided into three parts, the first giving results from evaluation of winter hardiness of velvet bentgrass under controlled conditions, the second describing experimental layout and preliminary results from two field trials with fertilizer levels, thatch control methods and topdressing levels; and the third describing experimental layout and preliminary results from a lysimeter study on irrigation stategies for velvet bentgrass on greens varying in rootzone composition.

Abstract

The control of Alopecurus geniculatus, Poa annua and Poa trivialis using iodosulfuron (Hussar/Hussar OD) was investigated in field experiments in the seed harvest year in timothy (Phleum pratense), and in the sowing year and seed harvest year in smooth meadow-grass (Poa pratensis) and red fescue (Festuca rubra). Iodosulfuron (10 g a.i. ha-1) usually had good effect on Poa trivialis and Alopecurus geniculatus. As for Poa annua the effect on seed contamination was better than on weed coverage in the field. Early application improved weed control in the seed harvest years, and iodosulfuron was shown to perform well at low temperatures. The herbicide often delayed timothy development, but caused seed yield reduction only in two out of eight experiments, both with moist soil at treatment. The visual damage increased with increasing rates and use of additives (alcoholetoxylate or rape oil). A questionnaire investigation among timothy growers in 2004 showed that farmers using Hussar had 43% lower contamination of P. trivialis in cleaned seed yield and 20% lower yield than the farmers not using Hussar. In some trials in timothy and smooth meadow-grass, the new formulation Hussar OD gave slightly more damage than the old formulation Hussar. While well-established timothy crops seem to tolerate some visual damage without seed yield reduction, the risk of yield reduction in first year crops can usually be avoided by splitting the application into 5 g a.i. ha-1 at 14 days intervals. In smooth meadow-grass and red fescue established without cover crop, repeated applications of 5 g a.i. ha-1 in the sowing year resulted in better control of P. annua and significant seed yield improvements compared to application only in the seed harvest year. Both Hussar and Hussar OD have off-label approvals for members of the Norwegian Seed Growers Association.

Abstract

During 2002-2005, Norwegian seed yields of meadow fescue (Festuca pratensis Huds.) were 52% lower in organic than in conventional seed production. The difference was most conspicuous in ley year 1, suggesting that seed crop establishment is a limiting factor in organic seed production. Meadow fescue is usually underseeded in a cover crop of spring wheat or spring barley, and many organic growers delay the underseeding until after harrowing for weed control. Our objectives were (1) to determine whether organic seed crops of meadow fescue should be underseeded in the same operation as, or immediately after, the cover crop (implying no harrowing for weed control); or if they should be underseeded in conjunction with, or just after, weed harrowing (on average nine days after the cover crop); and (2) to compare the establishment of meadow fescue seed crops without cover crop or in cover crops of spring barley, spring wheat, peas or green fodder (barley + peas). On average for all cover crops and four trials, first year’s seed yields of meadow fescue were 11 % lower for crops seeded after weed harrowing than for crop seeded immediately after the cover crop. Weed harrowing combined with delayed seeding also resulted in more scentless mayweed (Tripleurospérmum inodórum) and other weeds in ley year 1. Despite less plant-available nitrogen in spring, seed crops underseeded just after the cover crop were more lodged than crops underseeded after weed harrowing. On average for the two seeding dates, the highest seed yield were produced from crops seeded in pure stand and from crops that had been underseeded in green fodder and received an extra 30 kg N ha-1 in manure shortly after green fodder harvest in late July. The results suggest that seed crops of meadow fescue need ample supply of light, water and nutrients in August to produce a good seed yield in ley year 1.

Abstract

Twelve fertilizer/biostimulant products or product families were compared with mineral fertilizer in three two-year trials on USGA greens and sand-based football fields in southern Norway. Within each trial, all treatments were received the same amount of total nitrogen per year. Substitution of some of the mineral fertilizer with Gro-Power® improved turfgrass quality in one trial. Otherwise, the organic fertilizers and biostimulants producted results that were equal to or inferior to the control treatment. In conclusion, fertilization of sand-based golf greens and football fields ought to be based on light and frequent applications of mineral fertilizer throughout the growing season. Organic fertilizers and biostimulants can, at best, be supplements to such a fertilizer program.

Abstract

Norwegian agriculture is totally dependent on a safe supply of seed of winter-hardy timothy varieties. The annual seed consumption varies depending on the extent of winter damages, particularly in northern Norway, and the average seed yield varies with weather and harvest conditions in the seed-producing districts in the southeastern and central part of the country. To buffer these variations, seed companies always keep stocks corresponding to 50-100 % of the average annual seed consumption. Such large stocks are risky to maintain as seed lots will loose germination over time. Our objective was to elucidate the effect of seed harvest time and seed storage location on the longevity of timothy seed. In 2003, timothy ‘Grindstad’ was combined directly on 2, 5 or 8 August corresponding to a seed moisture content (SMC) of 34, 27 and 20 %, respectively. After harvest the seed was dried to 10-11 % SMC. Germination analyses were accomplished 3, 15, 26 and 38 months after seed harvest; the three latter after splitting each seed lot into four sub-lots that were stored either in a conditioned seed store (4ºC, 30% RH), or in unconditioned warehouses at there climatically different locations. While seed harvest time had no effect on germination three months after harvest, differences became increasingly evident as time went by. After 38 months’ storage, seed stored in the conditioned store or in the warehouse at the continental location Tynset germinated, on average for harvest times, 15-16 units better than seed stored in the warehouse at the coastal location Vaksdal; and seed lots harvested at 20 % SMC germinated, on average for storage locations, 24 units better than seed harvested at 37 % SMC. While it has long been documented that direct combining at high SMC may damage seed germination, there has been less awareness that this damage may not manifest itself until after a certain storage period.

Abstract

The application of plant growth regulators (PGRs) and insecticides, either alone or in tank mixture, was tested in nine on-farm trials laid out according to three different experimental plans in SE Norway (59-61ºN) from 2002 to 2006. The first plan compared the PGRs trinexapac-ethyl (125 or 250 g a.i. ha-1), chlormequat chloride (2000 g a.i. ha-1) and ethephon (240 g a.i. ha-1) applied on two dates and compared with an untreated check. On average for three trials, seed yield of the diploid cv. Nordi (origin 61ºN) increased 15 % by application of trinexapac-ethyl (250 g a.i. ha-1) at stem elongation, decreased 18 % by application of ethephone at flower bud emergence, and was not significantly affected by any of the other treatments. The diploid cv. Bjursele (two trials) and the tetraploid cv. Betty (one trial) showed no response to any of the PGRs. In the second experimental plan, laid out in two seed crops of the diploid cv. Lea in 2005, trinexapac-ethyl (125 or 250 g a.i. ha- 1) was applied alone or in tank mixture with the insecticides alpha-cypermethrin (20 g a.i. ha-1) or dimethoate (500 g a.i. ha-1) on two dates. These trials verified the positive effect of trinexapacethyl, but the insecticides had no significant effect, which is not surprising as no harmful insects were detected. The third experimental plan compared insecticides at two developmental stages in a seed crop of cv. Lea with a high occurrence of Apion seed weevil and the lesser clover leaf weevil Hypera nigrirostris. In this trial, alpha-cypermethrin increased seed yield by 14 % when applied at flower bud emergence. Effective from 2004, Moddus 250 EC (trinexapac-ethyl) was approved in Norwegian seed production of selected cultivars of red clover. Research is still underway to evaluate the need for control of various weevils.

Abstract

Since the formation of the International Herbage Seed Group (IHSG, formerly IHSPRG) in 1978, International Herbage Seed Conferences have been organized, mostly at four year intervals. The Sixth Conference was held at Gjennestad Horticultural College in Vestfold, Norway, from 18 to 20 June 2007. As for other IHSG activities, the objective of the conference was ‘to encourage cooperation and communication between workers actively engaged in herbage seed production research’. About 80 delegates from 20 countries attended the conference. Four invited and almost sixty voluntary papers were presented, either orally or as posters. The topics were split into the following sessions: 1. Opening session with overview over herbage seed production and seed trade, world wide. 2. Herbage seed for the future: Biodiversity, GMOs and the role of seed yield capacity in herbage breeding programs. 3. Seed production of tropical species and species for stressful environments. 4. Physiological restraints to seed set and seed filling. 5. Establishing the potential for high and pure seed yields. 6. Fertility, plant growth regulators, and plant protection. 7. Statistical methods, seed harvest, and post-harvest issues.

Abstract

Tiller demography and contribution to seed yield were studied in first year seed crops of smooth bromegrass (SB, Bromus inermis ‘Lofar’) and meadow fescue (MF, Festuca pratensis ‘Salten’) planted on different dates and with increasing plant densities (A: 15 Jun. / 11 plants m-2, B: 15 or 30 July / 44 plants m-2, C: 15 August or 10 September /178 plants m-2) in field trials at Landvik, SE Norway. While the total tiller population in most crops increased until seed harvest, it decreased during panicle elongation in crops of SB and MF that had reached 2000 and 3500 tillers m-2 in early spring, respectively. Except for the fact that many of the primary tillers of SB died after producing barren stems, tillers formed in August and September had the greatest chance of becoming reproductive and produced the heaviest inflorescences in both species. Most tillers produced in winter or early spring either remained vegetative or died, but spring-emerging tillers contributed up to 30% of the total seed yield in early-established, low-density crops of MF. It is concluded that spring-emerged tillers contribute more to seed yield in MF than in SB and more in seed crops established early at low plant density than in crops established late at higher density.

Abstract

The three organic cropping systems Landvik (in Grimstad), Voll (at Ås) and Kvithamar (in Stjørdal) were established in 1993 on previously conventionally farmed soils of marine origin. The six-year crop rotation at Landvik was designed for an organic stockless farm producing cash crops. These crops were fertilized with composted organic household waste from the nearby community (maximum 100 kg N ha-1) and composted waste from the system itself. The rotation at Voll was designed for an arable farm withbeef production from suckling cows (0.9 animal units ha-1), and the rotation at Kvithamar was designed for a dairy cattle farm (1.0 animal unit ha-1). During the first six years of organic farming, the soil reserves of K were slightly depleted. The nutrient balance was –250 kg K ha-1 at Voll and –420 kg K ha-1 at Landvik, and the content of easily soluble K in the plough layer decreased at these sites. At Kvithamar, however, where the K balance for six years was –380 kg ha-1, no changes in soil content of K were recorded. For P, the six-year balance was positive at Landvik, where altogether 120 kg P ha-1 was supplied from composted household waste. The P balance was negative (-40 kg ha-1) at Voll and Kvithamar, and at Voll the content of easily soluble P in the plough layer was lower in 1999 than in 1993. In the study period, the yields were variable both within and between the systems. We have not identified any trends or variations in yields that might have been directly caused by changesin soil nutrient status or other soil quality components. At Voll and Kvithamar, however, the number of earthworm and the soil macroporosity increased from 1993 to 1999, with a concurrent slight increase in the yields of leys (Voll) and grain crops and swedes (Kvithamar). In the system at Landvik the yields of potatos and carrots were higher the first two than the last four years. At this site the soil structure was good, and the porosity and earthworm activity high, during the whole study period.