Figure 1. The mixed plots in February 2022. The border row in the middle is with pure fescue; Experiment 1 with high nitrogen/low mow is to the right of that; and Experiment 2 with low nitrogen/high mow is to the left. Photo by Karin Juul Hesselsøe
This research aimed to determine if creeping bentgrass (Agrostis stolonifera) can be used as an alternative to colonial bentgrass (Agrostis capillaris) in a mixture with red fescue (Festuca rubra — a blend of 50% Chewings fescue and 50% slender
creeping red fescue) on Scandinavian golf greens managed without pesticides. As an add-on to the Scandinavian Turfgrass and Environment Research Foundation’s SCANGREEN variety testing from 2019-2022, the mixtures were compared in two experiments:
Experiment 1, with high nitrogen and low mowing, and Experiment 2, with low nitrogen and high mowing. Preliminary observations in the ongoing trials (2019-2022) show that red fescue plus creeping bentgrass produce greens of higher or equal quality
and with less Microdochium patch than red fescue plus colonial bentgrass, though the competition on red fescue from the creeping bentgrass should be taken into notice, especially at the high-nitrogen/low-mowing management regime.
Since 2003, the main objective of the SCANGREEN program has been to develop in-depth knowledge of turfgrass species and new cultivars for sustainable and integrated pest management of Scandinavian putting greens (1, 4). Until 2014, the trials were limited
to pure species and cultivars, but since 2015, they have included selected seed blends and mixtures to determine their suitability for use on putting greens managed without pesticides (2). In Norway and Denmark, only 30% to 40% of golf courses have
greens initially seeded with creeping bentgrass. Most of the remaining golf courses have greens that were initially seeded with a mixture of colonial bentgrass and red fescue. Over time, these greens often suffer from diseases — mainly Microdochium
patch (Microdochium nivale) — and the ingression of annual bluegrass (Poa annua). Mixtures of red fescue and creeping bentgrass, as well as mixtures of red fescue, creeping bentgrass and colonial bentgrass, are commonly used for putting greens
in Germany, but these mixtures had not been evaluated in Scandinavian trials up to 2015. Influenced by British traditions, it is often argued that the ecological adaptations of red fescue and creeping bentgrass are too dissimilar to be compatible
on greens. Results from SCANGREEN 2015-2018 showed that red fescue plus creeping bentgrass produced greens of equal quality and with less Microdochium patch than red fescue plus colonial bentgrass under both management regimes. Tiller counts in the
mixed plots showed that red fescue was not outcompeted by bentgrass in any of the mixtures (3). The objective of this research was to evaluate turfgrass quality and occurrence of Microdochium patch on mixed red fescue-bentgrass greens with more competitive
cultivars of bentgrass and fescue and to explore the potential for a triple mixture with red fescue, colonial and creeping bentgrass.
Table 1: Treatment codes, set blends and mixtures in weight ratios included in experiments 1 and 2.
Materials and methods
Trials were seeded on sand-based greens constructed according to USGA recommendations at the Norwegian Institute of Bioeconomy (NIBIO) Research Center, Landvik, Norway. Landvik has a coastal climate with an annual mean temperature of 46 F (7.8 C) and
annual precipitation of 55.75 inches (141.60 centimeters) (reference period 1991-2020). Each experimental green included two experiments: Experiment 1, with a fertilizer rate of 3.5 pounds nitrogen per 1,000 square feet per year (17 grams nitrogen
per square meter per year) and a mowing height of 0.12 inches (3 millimeters), and Experiment 2, with a fertilizer rate of 2.3 pounds nitrogen per 1,000 square feet per year (11 grams nitrogen per square meter per year) and a mowing height of 0.2
inches (5 millimeters). These fertilizer levels and mowing heights are typical for creeping bentgrass greens and red fescue/colonial bentgrass greens in the Scandinavian countries.
The four mixtures/blends compared in the experiments were: FR + AC — a red fescue seed blend in mixture with colonial bentgrass, which is the traditional mixture for golf greens in Scandinavia with a weight ratio of 85% red fescue and 15% colonial
bentgrass; FR + AS — where colonial bentgrass was changed to creeping bentgrass with the same weight ratios; FR + AC + AS — a triple mixture including all three species, where the 15% bentgrass was divided equally in colonial and creeping
bentgrass; and FR — a seed blend of red fescue only (Table 1). The red fescue seed blend comprised three cultivars: one slender creeping red fescue, Cezanne; and two Chewings fescues, Musica and Barlineus. The cultivars of colonial and creeping
bentgrass were Greenspeed and Pure Distinction. These cultivars are among the most widely used in the Scandinavian countries, and most of them are also long-term controls in the SCANGREEN program. Each experiment had three blocks (replicates) with
free randomization of the blends and mixtures within each block.
Figure 2. An overview of the whole Scangreen trial area in early October 2021. Note the darker green color of Experiment 1 at the left side of the trial compared to Experiment 2 on the right. Photo by Karin Juul Hesselsøe
The greens were mowed three times per week and deficit-irrigated to 80% of field capacity three to four times per week in periods without sufficient natural rainfall. Fertilizer (mean N-P-K ratio, 100-22-74) was given as completely balanced compound fertilizers
every second week. Wear was simulated using friction wear drums with golf spikes corresponding to an average of 11,000 rounds of golf per year. There was no use of pesticides or plant growth regulators in any of the trials.
Turfgrass visual quality was assessed once a month from May to November on a scale from 1 to 9, where 9 is the highest quality and 5 is the lowest acceptable quality. Microdochium patch was recorded visually as a percentage of plot area immediately after
snowmelt and during the monthly assessments in October and November.
The species composition in all plots seeded with red fescue–bentgrass mixtures was determined in October 2020 and 2021. Five random samples were taken as small cylinders (0.43 square inches/2.8 square centimeters) from each plot, and the number
of tillers of each species was counted under a magnifying lens.
Turfgrass visual quality
At the high-nitrogen/low-mowing management regime, the mixture with red fescue and colonial bentgrass (FR + AC) had lower turfgrass quality in 2020 and 2021. In June 2020, the mixture with creeping bentgrass (FR + AS) had significantly higher turfgrass
quality than the others (Figure 3), and the FR blend had the lowest quality. In November 2020, significantly lower turfgrass quality in FR + AC compared to FR + AS and FR blend was observed. The triple mixture was in between. Almost the same pattern
was seen in 2021, where turfgrass quality was highest in FR blend in May, while FR + AC was lower than the others in May and June. In October, FR + AC and the FR blend was lower than FR + AS (Figure 4).
At the low-nitrogen/high-mowing management regime in 2020 and 2021, the mixtures with fescue and bentgrass performed similarly, but in August and November 2020, the triple mixture (FR + AC + AS) was better than the others (data not shown). In 2021, the
seed blend with red fescue FR performed better in May and November, while FR + AC was inferior (data not shown).
Figure 3. Turfgrass visual quality in 2020 at high nitrogen in red fescue blend (FR), mixture of red fescue and colonial bentgrass (FR + AC), red fescue and creeping bentgrass (FR + AS) and red fescue, colonial and creeping bentgrass (FR + AC + AS). Rating values 5 or above are acceptable. Before = March. Different letters (a, b and c) indicate significant differences among mixtures.
Figure 4. Turfgrass visual quality in 2021 at high nitrogen in red fescue blend (FR), mixture of red fescue and colonial bentgrass (FR + AC), red fescue and creeping bentgrass (FR + AS) and red fescue, colonial and creeping bentgrass (FR + AC + AS). Rating values 5 or above are acceptable. Different letters (a, b and c) indicate significant differences among mixtures.
Under the high-nitrogen/low-mowing management regime, the disease pressure was low in the first year after grow-in (below 1% in March 2020), but in November 2020, the mixture with colonial bentgrass (FR + AC) had significantly higher incidence of Microdochium
patch than the other mixtures (Figure 5). These differences were still seen after snowmelt in March 2021, where FR + AC had a tendency (p=0.12) to higher incidence of Microdochium patch. The following autumn/winter, higher disease pressure was seen
in FR + AC and FR + AC + AS than in the FR + AS and the FR blend, but the differences were not significant (data not shown). At the low-nitrogen/high-mowing management regime in 2020, FR + AS had high incidence of Microdochium patch in March, but
the difference from the other mixtures was not significant. In November, the situation was changed, and FR + AC had significantly higher attacks of Microdochium patch than the FR blend and the FR + AS mixture (Figure 6). At the assessments in 2021,
the same pattern was seen, and preliminary results from January to March 2022 show the same tendency (data not shown). These results confirm earlier observations, that colonial bentgrass is more affected by Microdochium patch than creeping bentgrass
in autumn (October and November), while creeping bentgrass is more affected through the winter (1).
Botanical composition (competition between fescue and bentgrass)
In the first year after grow-in, the proportion between red fescue and bentgrass was in favor of the bentgrasses in the high-nitrogen/low-mowing management regime with the highest proportion of bentgrass in the mixture with creeping bentgrass, followed
by the triple mixture and then the mixture with colonial bentgrass. At the low-nitrogen/high-mowing management regime, the proportion between fescue and bentgrass was more balanced, though the triple mixture was in favor of the bentgrasses.
In 2021, the dominance of the creeping bentgrass was clear in the high-nitrogen/low-mowing management regime, where red fescue was almost outcompeted in the mixture with creeping bentgrass. In the triple mixture, the proportion of bentgrass had also increased
from 2020 to 2021, while the proportion of colonial bentgrass had decreased from 2020 to 2021 in the mixture with fescue and colonial bentgrass.
At the low-nitrogen/high-mowing management regime, the proportions between fescue and bentgrass in the FR + AC and FR + AS mixtures were similar to those in the first year, while the proportion of bentgrass had decreased in the triple mixture from 2020
Figure 5. Percentage of Microdochium patch in 2020 at high nitrogen and low mowing in red fescue blend (FR), mixture of red fescue and colonial bentgrass (FR + AC), red fescue and creeping bentgrass (FR + AS) and red fescue, colonial and creeping bentgrass (FR + AC + AS). Different letters (a and b) indicate significant differences.
Figure 6. Percentage of Microdochium patch in 2020 at low nitrogen and high mowing in red fescue blend (FR), mixture of red fescue and colonial bentgrass (FR + AC), red fescue and creeping bentgrass (FR + AS) and red fescue, colonial and creeping bentgrass (FR + AC + AS). Different letters (a and b) indicate significant differences.
The preliminary findings from 2020-2021 confirm the results from SCANGREEN 2015-2018 (3) showing that red fescue plus creeping bentgrass can produce greens of equal or even higher turfgrass quality than red fescue plus colonial bentgrass under both management
regimes. The lower turfgrass quality in FR + AC compared to FR + AS (Figures 3 and 4) can be explained by the higher incidence of Microdochium patch (Figure 5) in that mixture. Unfortunately, the preliminary results on species composition show that
the creeping bentgrass is more competitive with the fescue than the colonial bentgrass at the high-nitrogen/low-mow management regime, where the fescue is almost outcompeted after two years. At the low nitrogen/high mow management regime this is not
the case. Results from the last experimental year (2022) will show the further development in the species composition in the mixtures.
The triple mixture, where red fescue was mixed with equal proportions of colonial and creeping bentgrass, performed almost like the FR + AS mixture. The triple mixture had not been tested in earlier trials, but especially at the low-nitrogen/high-mow
management regime, it performed well in 2020 and 2021.
Based on the results so far, we can recommend the mixture of red fescue and creeping bentgrass as an alternative to the mixture of red fescue and colonial bentgrass, because it has higher turfgrass quality and less Microdochium patch. To retain a balanced
proportion of fescue in this mixture it should be managed with not more than 2.3 pounds of nitrogen per 1,000 square feet per year and a mowing height of 0.2 inches. The third year of assessments are being conducted in 2022, when the final results
will be collected.
The Research Says
- A mixture of red fescue plus creeping bentgrass can produce greens of equal or even higher turfgrass quality than red fescue plus colonial bentgrass under two management regimes.
- A mixture of red fescue and creeping bentgrass is recommended as an alternative to the mixture of red fescue and colonial bentgrass, because it has higher turfgrass quality and less Microdochium patch.
- A triple mixture of red fescue mixed with equal proportions of colonial and creeping bentgrass performed almost as well as the red fescue/creeping bentgrass mixture.
- Aamlid, T.S., W. Waalen, G. Thorvaldsson, A.M.D. Jensen, et al. 2015. SCANGREEN 2011-2014: Turfgrass species and varieties for Integrated Pest Management of Scandinavian Putting Greens. Bioforsk Report 10(65):1-91.
- Aamlid, T.S., P. Heltoft, G. Thorvaldsson, A.M.D. Jensen, T. Espevig, K.J. Hesselsøe, et al. 2019. SCANGREEN 2015-18: Turfgrass species, varieties, seed mixtures and seed blends for Scandinavian putting greens. Final results from a four-year
testing period. NIBIO Report 5(154):1-100 (http://www.sterf.org/Media/Get/3293/nibio-report_scangreen_2015-18_kjh-tsaa-final-161219.pdf).
- Hesselsøe, K.J., P. Heltoft, T. Espevig and T.S. Aamlid. 2022. Seed mixtures of red fescue and colonial, creeping or velvet bentgrass for pesticide-free management of Nordic golf greens. International Turfgrass Society Research Journal 1-7
- NIBIO (2022): SCANGREEN Scandinavian Testing Program for turfgrass species and varieties on sand-based golf greens (Infovideo) https://youtu.be/Bp3fzu2y7OM.
Karin J. Hesselsøe (firstname.lastname@example.org) and Anne F. Borchert (email@example.com) are research scientists, and Trygve S. Aamlid (firstname.lastname@example.org) is a research professor, in the Turfgrass Group at the Norwegian Institute of Bioeconomy Research in Landvik, Norway. Pia Heltoft (email@example.com) is a research scientist at the Norwegian Institute of Bioeconomy Research in Apelsvoll, Norway.