Introduction

Fine fescue (Festuca spp.) turfgrasses have been shown to be among the most shade tolerant cool-season turfgrasses through anecdotal and scientific evidence (Petrella and Watkins, 2021; https://doi.org/10.1002/csc2.20279). This group of cool-season consists of multiple related species that can often look quite similar, but perform very differently under various types of stresses. The most commonly used fine fescues include strong creeping red (Festuca rubra L. ssp. rubra Gaudin; STF), slender creeping red (F. rubra L. ssp. littoralis (G. Mey.) Auquier; SLF), Chewings (F. rubra L. ssp. commutata Gaudin; CHF), hard (F. brevipila Tracey; HDF), and sheep fescue (F. ovina, L.; SHF).

Most data has indicated that Chewings and strong creeping red fescue cultivars are the most tolerant to foliar-shade (shade from trees and/or shrubs), but that doesn’t mean that other fine fescues are not shade tolerant. Fine fescues are in general extremely variable within species; some Chewings fescue cultivars are great in shade, some are bad; a lot of hard fescues are not the best in shade, but some are great in shade (Figure 1).

Figure 1: All fine fescues are thought to be great in shade, regardless of species or cultivar, this is not true. Some cultivars of the same species are very good under shade while others can be very bad. Choice of fine fescue cultivar under shade may be more important than species itself.

Shade is a very difficult environment for turfgrasses to grow in due to shade consisting of multiple stresses; competition for water and nutrients with trees, higher humidity, cool days followed by warmer nights, reductions in light intensity, alterations in spectral quality – alterations in the color of the light after being filtered by the tree leaves, and sudden exposure to short periods of high-intensity light (sun flecks; dappled shade). All of these stresses make real-world shade research difficult – some plots may be in a very different environment compared to others and results from this trial show this variation.

The objective of this trial was to examine variation in shade tolerance among hard fescue, strong creeping red fescue, and Chewings fescue cultivars under tree shade in Columbus Ohio.

Materials and Methods

Plots were established at the Ohio Turfrgass Foundation (OTF) research and education center on 9/28/18 by Dr. Ed Nangle and Dr. David Gardner. A total of 16 fine fescue entries were evaluated; 6 Chewings fescues, 5 strong creeping red fescues, and 5 hard fescues (Figure 2 and 3). All cultivars were seeded at a rate of 5 lbs. of seed per 1,000 sq. ft.

Starter fertilizer was applied at 1.0 lbs. of nitrogen per 1,000 sq. ft. on 10/2/18 (14-28-10) along with a pelletized paper mulch at 25 lbs. of product per 1,000 sq. ft. No supplemental irrigation was applied at establishment or during the entire trial.

Figure 2: Fine fescue species and cultivars used in this trial.

Figure 3: Layout of fine fescue trial at the OTF center in Columbus Ohio.

Plots were maintained with minimal maintenance and were only mowed once per week at 4.0 inches during 2019 and 2020. Mowing was infrequent to absent during 2021 and plots were not mowed until July 2022.

In 2022, plots have only been mowed three times (July 11th, 21st, and 27th) and no pesticides or fertilizer has been applied.

Results and Discussion

As of summer 2022 there were no significant differences in turfgrass density or turfgrass quality between the species and the cultivars used (Figure 4 and 4). However, this is primarily due to the large amount of variation in the trial. For example, ‘Radar’ Chewings fescue had acceptable turfgrass quality in replicates 1 and 2, but the placement of replicate 3 was in an extreme location leading to a large decline in density and quality – the same for ‘Shademaster III’ strong creeping red fescue.

Figure 4: Turfgrass density and quality for the fine fescues species used in this study on July 27th 2022.

Figure 5: Turfgrass density and quality for the fine fescues cultivars used in this study on July 27th 2022.

Few fine fescue cultivars showed consistent results across all replicates. However, ‘Aberdeen’ strong creeping red fescue (Figure 6), ‘Minimus’ hard fescue (Figure 6), ‘Momentum’ Chewings fescue (Figure 6), and ‘Chantilly’ strong creeping red fescue (Figure 6) were consistently the best entries as of July 27th 2022 (7-27-22 Fine fesuce shade plot pictures; 7-27-22 Fine fescue shade trial overhead drone pictures).

Figure 6:Drone pictures of plots taken on July 27th 2022.

The way in which these cultivars gained higher visual density and quality varied. Some cultivars had shorter leaves and more tillers to cover the soil surface, while other cultivars had less tillers and longer leaves that laid over to cover the soil. While these cultivars gained shade tolerance differently, the way in which they are managed may make some lose turfgrass quality. For example, cultivars that exhibit shade tolerance from longer leaves that lay over to cover the soil while having less tillers may not maintain high turfgrass quality when mowed at a lower height or when mowed frequently. While cultivars with more tillers and shorter leaves may maintain quality under different management practices.

The study will continue over the next few years in order to gain a better understanding of how turfgrass quality and density changed under shade over time to help us better understand what traits lead to improved shade tolerance in fine fescue species.

Introduction

Sometimes you get a hunch to try a different management practice, but might not want to try in fear of negative consequences. That’s where turfgrass researchers come in! In spring of 2021, Gary Deters, former golf course superintendent at St. Cloud Country Club (St. Cloud MN) and current field manager for the University of Minnesota (UMN) turfgrass research program had one of those hunches for quite awhile that he wanted to investigate.

Gary and other Minnesota golf course superintendents wondered what the consequences would be if you rolled a putting green directly after it been sprayed with fungicide. Would the fungicide be removed? Would the fungicide be spread better? Would you end up wasting money and get huge disease breakout? This idea came about due to changes in labor availability that has hit the golf course management industry and the need to sometimes do things differently when the need arises.

Results from the trial at UMN in 2021 indicated that when using Secure Action (Acibenzolar-S-methyl, Fluazinam) @ 0.50 fl. oz. per 1,000 sq. ft. there were no apparent negative consequences if the plots were rolled right after spraying (Figure 1).

Figure 1: Drone picture of 2021 trial at University of Minnesota (UMN).

However, there was little to no disease pressure on these plots in 2021 (besides some brown patch outside of the plot area!). Still we could see the effects of the Acibenzolar-S-methyl on fungicide treated plots whether they were rolled or not – these plots were darker green compared to plots not treated with fungicide (Figure 2).

Figure 2: Plots treated with Secure Action were darker green due to Acibenzolar-S-methyl regardless of being rolled after application.

Data for the normalized difference vegetation index (NDVI) also showed that rolling did not remove the Secure Action from the leaves – leading to darker green turf (Figure 3).

Figure 3: NDVI on plots at UMN treated with Secure Action (@ 0.50 fl. oz. per 1,000 sq. ft.) and rolled after treatment or not rolled after treatment. Higher NDVI indicates darker green turf.

It was good to see that the Acibenzolar-S-methyl still was impacting the turf regardless of being rolled or not, but the lack of disease still made us wonder if this management practice was a good idea. Therefore, we have repeated the trial at the Ohio Turfgrass Foundation (OTF) center to see if we could get more disease on this trial.

Materials and Methods

The trial was initiated at the OTF center in Columbus Ohio on May 11th 2022 on a native soil bentgrass surface maintained as a putting green. The plot area was mowed at 0.125″ 4-5 days per week and was brushed daily unless under high stress. In July, plots were not mowed first thing in the morning to keep the dew on the plots longer in order to promote dollar spot disease. Primo (trinexapac-ethyl) was applied on June 8th, June 15th, June 29th, and July 11th @ 6 fl. oz. per acre.

Plots were treated with Secure Action (Acibenzolar-S-methyl, Fluazinam) @ 0.50 fl. oz. per 1,000 sq. ft on approximately every 14 days (May 11th, May 27th, June 10th, June 24th, July 7th, and July 22nd). Rolling treatments were applied to non-fungicide treated plots first, and was then applied to fungicide treated plots directly after Secure Action application.

Results and Discussion

There was no significant difference in turfgrass quality prior to treatment initiation on May 11th (Figures 4 and 5).

Figure 4: Plot appearance prior to treatment initiation.

Figure 5: Turfgrass quality of plots prior to treatment initiation.

As of July 27th 2022 results indicate the rolling after an application of Secure Action does not change fungicide efficacy or alter turfgrass quality. Turfgrass quality was significantly increased with Secure Action application, regardless of rolling (Figure 6), and dollar spot disease was significantly  suppressed with Secure Action application, regardless of rolling (Figure 7).

Figure 6: Turfrgass quality on July 27th 2022.

Figure 7: Number of dollar spot disease infection centers on July 27th 2022.

Not only was dollar spot disease significantly suppressed still if Secure Action treated plots were rolled right after, but the simple application of Secure Action lead to improvements in visual quality – noticeable across all replicates (Figure 8).

Figure 8: Plot appearance on July 27th 2022.

As of now the results indicate that at least with a contact fungicide (though Acibenzolar-S-methyl is systemic) rolling after application does not reduce the effects of the fungicide. This type of management practice could be useful during panic periods when staff is low and fungicide needs applied ASAP in the morning before more workers comes in. In the future, we will examine this further using different products and standard fungicide roations to see what happens when more than contact fungicides are used.