Field Days 2022

Refining best management practices for nitrogen applications to cool-season turfgrass lawns across Ohio

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Refining best management practices for nitrogen applications to cool-season turfgrass lawns across Ohio

T. VanLandingham, D. Petrella, E. Nangle, D. Gardner.

Introduction:

Turfgrass lawns need nitrogen fertilizer to be healthy. Healthy turfgrass areas provide erosion control, temperature control, increase air quality, purify water, sequester carbon, and increase quality of life for humans. There are currently NO guidelines for annual rates of nitrogen fertilizer applications in the state of Ohio. A survey from the Ohio Lawn Care Association found that respondents applied between 1.5 and 7 lbs/1000sqft of nitrogen to turfgrass lawns over the course of a growing season. Over-fertilization contributes to more surface runoff and leaching of nitrogen into water sources, affecting water quality and negatively impacting the environment. This issue is a concern for the state of Ohio and so industry needs guidelines to help them provide high quality surfaces while having minimal impact on the environment.

The objectives of this trial were to develop refined best management practices for nitrogen fertilizer applications for home lawns and high-cut turfgrasses across Ohio and examine to what extent different turfgrass species and new turfgrass cultivars affect nitrogen needs in order to reduce nitrogen fertilizer use.

Materials and Methods:

Four locations were chosen across the state of Ohio to encompass as much climate variability as possible: Columbus, Cincinnati, Wooster, Findlay. The seeding dates and cultivars can be found below (Table 1). All sites were set up as randomized complete block (RCB) split-plot design w/ repeated measures accounting for nitrogen applications. Annual Nitrogen (N) rates were 0.0, 0.5, 1, 2, 4lbs N/M/yr and treatments were split monthly from May-September. Plots are 3ft by 3ft in size with four species and five cultivars per species being evaluated.

All cultivars seeded at 2 PLS cm-2, using germination data and 1.0 lb of P (0.5 lb N) applied at seeding and 0.5 lb N was applied 2-3 weeks after seeding. All plots were covered with Futtera EnviroNet and irrigated during establishment and once mowing began plots were mowed every 7 days in 2023 at 3.5”. After establishment unless environmental conditions became extreme irrigation was not applied.

Table 1. Seeding dates, turfgrass species and cultivars used during trial focused on refining best management practices for nitrogen applications to cool-season turfgrass lawns across Ohio

Sites Tall Fescue Hard Fescue Kentucky Bluegrass Perennial Ryegrass
Cincinnati (Blue Ash) Hemi Hardtop Dauntless Accent II
Columbus (OSU) Bullseye Jetty Aviator II Fastball 3GL
Wooster (OSU) Raptor III Nanook BlueNote Overdrive 5G
Findlay (OSU) Zion Tenacious Mercury Silver Sport
  Rhizing Moon Minimus Moonlight SLT SR4700

Data was collect bi-weekly from April-November at all four sites. Growth was measured in avg daily height using laser distance device (Bosch) and calculated based on time after mowing. Turfgrass health and vigor were evaluated using normalized difference vegetation index (NDVI) (Trimble Inc) while density was analzyzed using light box photos and the turf analyzer software. Soil tests were carreid out in year 1 and will be carried out again in year two. Weather data is being collected using weather stations (Meter Group) at each location. Soil water potential was quantified and and only irrigate when necessary.

Results:

Hard fescues and Kentucky bluegrasses failed to establish in Wooster; Hardtop was the best-established hard fescue in Wooster. Tall fescue is performing surprisingly poor in Findlay, regardless of the nitrogen applied. Kentucky bluegrass did not establish well at either of the Columbus or Blue Ash locations, Tall fescue is the top performer thus far at these two locations. Color differences across all cultivars is the most notable among the different nitrogen rates, especially with the Hard fescues.

Image overview of Columbus plot location with N=400 3’x3’ plots

 

Active blog site which provides updates and results: https://u.osu.edu/homelawnfertilizer/

 

Overview of rep 4 at the Columbus location showing the five levels of nitrogen rates color coded by treatment level. Photo taken two weeks after initial fertilizer application. White (0lbs N/M/yr), Blue (0.5lbs N/M/yr), Yellow (1 lbs N/M/yr), Green (2 lbs N/M/yr), and Red (4lbs N/M/yr).

 

 

Acknowledgements:

Funding for Project was made possible by the U.S. Department of Agriculture’s (USDA) Agricultural Marketing Service through grant AGR-SCBG-2022-02. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA

 

 

Mowing Frequency Impacts on Tall Fescue Cultivars

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Mowing Frequency Impacts on Tall Fescue Cultivars

Tyler Carr

Assistant Professor and Turfgrass Extension Specialist

Introduction:

Turfgrasses are often perceived as extreme users or resources. Turfgrass breeding efforts have developed cultivars that require reduced inputs from fertilizer, water, pesticides, and labor. Mowing is a significant labor expenditure while also contributing to increased emissions; therefore, identifying turfgrasses that require less mowing can help reduce labor and environmental impact from turfgrass management.

Materials and Methods:

This experimental area was seeded on October 3, 2022 at 6 lb/1000 square feet and overseeded at 3 lb/1000 square feet on April 6, 2023. Eight commercially-available tall fescue cultivars  were planted in individual plots:

  • Falcon V
  • Firecracker GLS
  • Gallardo
  • Kentucky 31 (low-performing standard)
  • Maestro
  • Raceway
  • Regenerate
  • Titanium

Mowing frequency treatments were initiated June 13, 2023 and will continue through the fall and in 2024:

  • 2x/week
  • 1x/week
  • 1x/2 weeks

Since treatment initiation, the experimental area has received zero pesticides, fertilizer, or supplemental irrigation.

Results:

  • To-date, no differences have been observed between mowing frequencies.
  • Limited differences are present between cultivars.

Conclusions:

  • This experimental area is rather juvenile and treatments were only initiated 7 weeks ago. The effects of mowing frequency are expected to be cumulative, and differences may also be observed during periods of active growth (spring and fall). As these grasses mature, we expect the different tall fescue cultivars to demonstrate differences in quality.

Wetting Agents to Prevent or Cure Drought Stress in a Mature, Push-Up Putting Green

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Wetting Agents to Prevent or Cure Drought Stress in a Mature, Push-Up Putting Green

Doug Karcher
Professor and Chair
Department of Horticulture and Crop Science

Background

Previous wetting agent research on putting greens has focused on sand-based greens using typical application schedules. There has been little work done on the effects of newer wetting agent products on drought stress and localized dry spot when applied on native-soil, push-up style greens, especially when applied at a single time, either as a preventative or a curative treatment.

Objective

  • To determine the effects of wetting agent application timing on the prevention and cure of localized dry spot on a mature, push-up putting green.

Methods

  • This experiment was initiated on June 14, 2022, on a mature push-up putting green comprised of a mixture of ‘Penncross’ creeping bentgrass and Poa annua. A rain-out shelter was constructed over the experimental area to prevent rainfall on the plots and to allow a thorough drying of the putting green root zone in the absence of irrigation.
  • Each of the following five wetting agent products and an untreated control treatment were applied in four separate plots. The experimental area was irrigated with approximately 0.1 inches of water within an hour of wetting agent application.
    1. Revolution (6 fl oz / 1000 ft2)
    2. Fleet (8fl oz / 1000 ft2)
    3. Vivax (5 fl oz / 1000 ft2)
    4. Excalibur (4 fl oz / 1000 ft2)
    5. Dispatch (24 fl oz / acre)
  • Wetting agent applications were made on the following dates:
    • Replicate 1 – 7 weeks prior to Field Day (June 14, 2022)
    • Replicate 2 – 6 weeks prior to Field Day (June 23, 2022)
    • Replicate 3 – 4 weeks prior to Field Day (July 7, 2022)
    • Replicate 4 – 2 weeks prior to Field Day (July 19, 2022)
  • The experimental area was irrigated as follows:
    • Best management practices from the initiation of the trial through July 10.
    • After July 10, irrigation was withheld to initiate drought stress and/or localized dry spot formation.
    • Irrigation practices resumed on July 28 once the experimental area had moderate to severe drought stress symptoms.
    • Based on this schedule, Replicates 1 – 3 are considered preventative applications and Replicate 4 is considered a curative application.

Results

  • Drought Stress / Localized Dry Spot
    • Evaluations were made at peak drought stress on July 28, and again on August 1, four days after recovery irrigation practices were initiated.
    • Although there were substantial differences in drought stress among treatment plots within each replication, these differences were not consistent across replications, which indicates either a high level of natural variability inherent within the mature, native soil green, or perhaps an interaction between wetting agent product and duration of preventative control, or curative ability.
    • Currently the best performing treatments at each application time are:
      • 7 weeks prior: Fleet
      • 6 weeks prior: Excalibur
      • 4 weeks prior: Excalibur
      • 2 weeks prior: Excalibur

 

  • Turf Quality
    • Plots were rated for visual quality on the same dates used to assess localized dry spot.
    • In this trial, turf quality was highly affected by drought stress. Therefore, turf quality results were very similar to those summarized for localized dry spot above.
    • There were no statistically significant differences in turf quality among treatments
  • Soil Moisture and Surface Firmness
    • Soil Moisture and Surface Firmness were measured daily during the final week of peak drought stress, from July 15 through July 28.
    • Soil moisture was assessed with a Sprectrum TDR 300 unit using a 3-inch rod depth. Measurements were taken in the center of each plot daily.
    • Firmness was assessed with a Spectrum TruFirm device. Measurements were taken in the center of each plot daily.
    • Wetting agent treatment did not affect rootzone moisture content or surface firmness on any measurement date. 

Conclusions

  • Wetting agents have been shown to be highly effective in reducing localized dry spot and increasing turf quality in sand-based putting greens. This is primarily due to the high levels of water repellency that naturally develop in such systems. The native soil green used in this experiment does not have a significant sand-topdressing layer, and therefore is much less prone to developing water repellency. Wetting agents may provide some insurance against drought symptoms in a native soil turfgrass symptoms, but they are much more effective when used in sand-based systems.
  • To conduct future impactful wetting agent research in Ohio, it will be important to develop sand-based, research putting greens.

Biostimulants and their impact on drought stress in Ohio during Summer 2022

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Biostimulants and their impact on drought stress in Ohio during Summer 2022.

 

E.J. Nangle1, T Morris1, D.P. Petrella1 S. Cusack2, B. Stith2.

1OSU CFAES Wooster Campus, 1328 Dover Rd, Wooster 44691

2OSU Turfgrass Research Facility, 2710 Northstar Road Columbus OH 43221

 

Introduction:

Drought stress has become an increased problem for turfgrass managers both in Ohio and across the Midwest with excessively dry periods combined with heat leading to large volumes of water use and concerns about turfgrass quality on high value surfaces. Traditionally golf course superintendents have relied on judicious use of fertility and water management combined with reductions in agronomic inputs to retain turf quality. Recently however with newer turfgrass cultivars emerging for putting greens and ever lower mowing heights there is added pressure to find extra roll and smoothness which has led superintendents to investigate the use of a class of products known broadly as ‘biostimulants’. Further to this, potential changes in legislation may begin to see curbs on pesticide applications. There is a two-fold need then to look more closely at these products and evaluate where they might fit into the golf course managers tool box and also compare these products against what might be considered traditional agronomic practices.

 

Materials and Methods:

This trial was initiated at the Ohio State University Turfgrass Research Facility in Columbus OH on June 9th 2022. Treatments were then applied on June 23rd, July 7th and July 21st. The trial was placed on a pushup rootzone with mixed annual bluegrass Poa annua creeping bentgrass Agrostis palustris cv. ‘Penncross’ stand. There were eight treatments with four replications, and they are shown in Figure 1. The treatments were laid out in a randomized complete block with dimensions of 0.91m x 1.83m. Treatments were applied using a CO2 backpack sprayer with a carrier volume of 300 L/ha. Treatments were applied for all products at the high label rate (Table 1). Plots were mowed daily at a height of 4.3 mm with clippings collected until the second week of the drought study when plots were only mowed twice.

All areas received current environmental conditions prior to July 13th 2022, with a last wetting agent application made on June 8th and preventative insecticide and fungicide treatments made through out the duration of the trial. On July 12th all supplemental irrigation was removed and a rain out structure was installed to prevent any external rainfall landing on the surface. This allowed for no water to be applied to the research surface for 16 days in total. On July 28th irrigation was applied to a depth of 2.45 cm on all plots and on July 30th irrigation was applied to a depth of 1.25cm.

During the trial color ratings were taken on a weekly basis on a 1-9 scale with 6 = acceptable. Normalized difference vegetation index (NDVI) data were collected as well as images collected using an NDVI camera weekly, stress on the plot (% of turf stressed) and turf quality with voids and loss of density being the main focus (1-9 scale with 6 = acceptable). During the dry down period firmness (depth of penetration in cm) (Spectrum Technologies, Trufirm) and soil moisture readings (% volumetric water content) Spectrum Technologies, TDR 300.

Five days post rewatering turf color, quality, percent stress and NDVI values were collected and analyzed. Data were analyzed using SAS 9.4. Weather data was collected at the site using a Campbell Scientific weather station.

A second trial site in Creston OH at Hawks Nest GC on a creeping bentgrass cv. ‘Pure Distinction’ putting green was run with the same methodology with the only differences being species type, rootzone construction and mowing height on the sites.

Figure 1. Plot layout with treatments and rates for treatments used in a trial evaluating biostimulants and their impact on drought stress in Ohio in the summer of 2022.

Treatment 5 Cytogro – .4 Floz/M = 1.1mL/1L
1 Griggs Bros Carboplex 6-4-4 – 6 Floz/M = 16mL/1L 6 Urea .1N/M = 9g/1L
2 Foliar Pak Foundation Forty 4-0-8 – 3 Floz/M = 7.9mL/1L 7 Harrells Bio Max Root Enhancer Iron (5%) plus Fulvic Acid – 6 Floz/M = 16mL/1L
3 Plant Food Co. Green T Impulse 6-0-0 – 9 Floz/M = 23.9mL/1L 8 Untreated
4 Progressive Turf Greater Green 5-0-7 – 12.8 Floz/M = 34.1mL/1L

 

Results:

 

Climatically conditions were both warm enough and dry enough to lead to drought stress occurring on the plots (Figure 2,3 and 4). Of interest was the relative humidity with average numbers at 50% or lower for an extended period during mid – late June (Figure 3).

 

Figure 2. Daily high temperatures Columbus OH during trial evaluating biostimulants and their impact on drought stress in Ohio in the summer of 2022.

Figure 3. Daily high temperatures in Columbus OH during trial evaluating biostimulants and their impact on drought stress in Ohio in the summer of 2022.

Figure 4. Average daily percent relative humidity in Columbus OH during trial evaluating biostimulants and their impact on drought stress in Ohio in the summer of 2022.

Quality ratings indicated that during the period where there was no limitation on irrigation or rainfall that there was very little difference between treatments. On D28 Urea provided significantly higher quality turf (p=0.05) than a majority of the treatments (Table 1). At D35 when drought stress was initiated urea was again rated amongst the highest treatments along with Harrells BioMax Root Enhancer, Plant Food Co. Green T impulse although only Urea was significantly higher than any of the other treatments (1,2,5,8). Ten days after drought initiation turf was all ratred above acceptable with minor differences being noted. At D52 all treatments showed a decline and only Harrells BioMax Root Enhancer, Urea and Plant Food Co. Green T Impulse were considered above acceptable quality (Table 1). There was no significant difference however between treatments at this time.

Table 1. Daily quality ratings for treatments during trial evaluating biostimulants and their impact on drought stress in Ohio in the summer of 2022.

†Means followed by different letters are significantly different at p=0.05

*Date rainout shelter was installed

Color ratings indicated that through D14 no differences existed while on D21 after initiation Urea rated highest with Harrells BioMax next and all other treatments rated significantly lower (p=0.05). At D35 prior to drought initiation greater variability existed with Urea, Progressive Turf Greater Green and Harrells BioMax providing the highest rated treatments. Only Harrells BioMax and Urea however were significantly higher (p=0.05) than the check plot. Ten days after initiation of the drought all treatments were the same and above acceptable color. D52 the final day of the drought stress showed a decline in some color with four treatments just below acceptable on average while Plant Food Co. Green T, Cytogro, Urea and Harrells BioMax providing turf color above acceptable with all others at or below that rating (Table 2).

Table 2. Daily color ratings for treatments during trial evaluating biostimulants and their impact on drought stress in Ohio in the summer of 2022.

†Means followed by different letters are significantly different at p=0.05

*Date rainout shelter was installed

Evaluations of stress development including wilt, loss of density and color indicated no issues arose until D45 which was 10 days after drought initiation. On that date Foundation 40 rated significantly higher than the Urea plots but not significantly different from any of the rest of the plots. On the final day of the trial Griggs Carboplex had on average 26.9% stress on the plots which was significantly higher (p=0.05) than both Urea and Harrells BioMax treatments (Table 3).

Table 3. Average percent of stress showing on plots for treatments during trial evaluating biostimulants and their impact on drought stress in Ohio in the summer of 2022.

†Means followed by different letters are significantly different at p=0.05

*Date rainout shelter was installed

 

Firmness data indicated that there were no differences between treatments on the final day of the drought study while some variability existed between treatments in regard to moisture. The untreated check had the lowest moisture ratings along side Progressive Turf treatments while Foliar Pak, Urea and Cytogro were found to have the highest moisture content, and this was significantly higher (p=0.05) than the check and Progressive turf only (Table 4).

Table 4. Volumetric water content and firmness readings on final day of drought study during trial evaluating biostimulants and their impact on drought stress in Ohio in the summer of 2022

†Means followed by different letters are significantly different at p=0.05

Conclusions:

This trial has shown that there is potential for some of these products to offer turf managers help during stressful periods. The application of urea however did act in a comparable manner to many of the treatments which was somewhat surprising. It must be noted of course that the urea rate was marginally higher than many of the treatments but is also an industry standard rate. Drought stress, heat stress and other environmental stresses are going to continue to occur and with greater frequency, turfgrass managers, researchers and companies are going to have to work together to utilize all tools available and thus these products deserve further attention and also different methods of analysis. It is expected this work will continue to run for many summers to come on a range of cultivars and soil types.

Putting Green Grain: Brushing Study

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Introduction

When turfgrass growth becomes horizontal the leaves begin to lie in various directions.  We call this grain.  Often times with grain turfgrass leaves are sporadically coarse in nature contributing to a general roughness to the turf.  Grain that occurs on putting green is considered negatively in that it impacts putting green consistency.  If you are putting with the grain (leaf blades laying away from you) the ball will tend to roll further or be “faster” than if you are putting against the grain (the leaf blades are laying toward you) which will be a much slower putt.  

Similarly, golfers may read a putt by looking at which way the grain is laying between the golf ball and the hole.  If the grain is toward the golfer the turf may appear a little darker green or conversely if it is laying away from the golfer the turf may be a little lighter color.  Grain can impact the amount of break in a putt.

Grain is often associated with the growth habit of the turfgrass species.  For example, creeping bentgrass is prostrate in growth while  annual bluegrass grows more upright.  Bermudagrass greens including the ultradwarf varieties frequently develop grain.  Grainy patches develop which is contrasted here between the green areas and lighter green patches. The patches or ares that develop on a bermudagrass green are often described as grain, but the cause may be due in part to genetic mutations.

Mechanical practices to remove grain and improve texture are primarily through mowing practices (frequency, height, direction), verticutting, groomers, brushing, and topdressing.  The goal is to get the turfgrass plants to grow vertically or “up-right” thus removing grain and improving density and texture of the turf.  

Results

For the last several years we have looked at the impact of brushing, including the evolution in brushing equipment on removing grain and improving putting green turf health.  In our field day presentation we will look at relatively low cost methods of brushing.  We are studying the impact of the brushing units on plant stress, green speed and overall quality, which is primarily the reduction in grain.  

Fine fescues for shaded areas

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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.

Rolling after putting green fungicide application

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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.

Turfgrass Weed Control Update

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Join me at 10:00 AM on field day when I talk about turfgrass weed management issues that I’m seeing or that have been reported to me in 2022.  There will also be a station rotation that demonstrates some newer and soon to be registered herbicides that I’ll compare to some industry standards.  I’ll also show a trial that looks at combinations of topramezone and quinclorac for control of crabgrass.

This link is to a general guide to turfgrass weed control

07 Weed Management

This link is to an article on some of the newer herbicides for turfgrass weed control

Turfgrass Weed Control 2022