Photoselective Filters Impact on Turf Quality

D. Petrella, M. Berger, E. Nangle, and T. Morris

Introduction:

Shade management strategies have used multiple approaches which include reductions in nitrogen rates, use of plant growth regulators, management of moisture content (Nangle et. al., 2012) and increases in mowing height as well as removal of trees and plant material surrounding area of importance that help with air movement. Research on shade however has required different approaches based on the portion of the industry that is affected. For example stadium shade or inert structure shade reduces light intensity but does not affect light quality and thus research that reports on use of shade cloth is pertinent for those situations (Russell et al., 2020). Research that focuses on plant (or tree shade) influences have shown that changes in growth habit and physiology are much greater compared to the shade cloth influence (Wherley et al., 2005, Petrella et al., 2020) and thus further work should be conducted with these materials. The reason for this difference is believed to be the reduction in the red far red ratio which occurs due to differential wavelength absorption by tree lines (Bell et al., 2005) The objective of this trial was to evaluate and compare the impact of the two types of shade materials and also investigate if a novel approach of cytokinin application could help alleviate some of the issues. Cytokinin is a plant hormone linked to enhanced cellular division as well as a promoter of branching and root growth and so this may offer a solution to aid in retention of turf quality..

Materials and methods:

This trial was established at three locations (2 in Wooster OH; 7-1-23 and 1 in Columbus; 7-6-23). Two of the surfaces consisted of newly established S-1 creeping bentgrass Agrostis stolonifera and the other surface was a mixed stand of annual bluegrass Poa annua and creeping bentgrass. Mowing heights were 0.130″ in Wooster and 0.150″ in Columbus. Surfaces were given approx approx 1.5lbs N to date in 2023 and fungicides were applied in a preventative manner. Growth regulator was applied only to the mixed annual bluegrass and creeping bentgrass stand every 14d at a rate of 12 fl oz/ acre of trinexapac ethyl. Data were collected for turf quality and normalized difference vegetation index as well as images collected using a photobox. MaxCell a synthetic cytokinin was applied on 7/12/23 at a concentration of 2.54 µmol. Data were collected for light intensity and light quality also. Light quality data indicated full sun R:FR of approx 1.2-1.3, Shade cloth R:FR was measured between 1 and 1.2 (plants respond above 1 similar to full sun) and the filters were measured at 0.2.

Results:

The impact of the filters was clearly noted on the more established plots in Wooster OH with a faster and more severe negative response to the change in light quality. The application of the cytokinin based product (not currently labelled for turf) did not provide immediate improvement and there may be a need to evaluate the product from a rate standpoint. Currently the recommendations for reducing nitrogen inputs, use of plant growth regulators, closely monitoring irrigation requirements and, selective pruning and  tree removal where possible are all approaches that should be implemented to aid with maintenance of turfgrass quality during the heavy summer paying season.

Impact of photoselective filters on turf quality and applications of MaxCell to ‘S-1’ Creeping bentgrass summer 2023, Columbus OH

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

Impact of photoselective filters and applications of MaxCell on NDVI values of ‘S-1’ Creeping bentgrass summer 2023, Columbus OH

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

Figure 1. Plot plan for trial evaluating Impact of photoselective filters and applications of MaxCell on NDVI values of ‘S-1’ Creeping bentgrass summer 2023, Columbus OH

References:

Bell, G.E., Danneberger, T.K. and McMahon, M.J. (2000), Spectral Irradiance Available for Turfgrass Growth in Sun and Shade. Crop Sci., 40: 189-195. https://doi.org/10.2135/cropsci2000.401189x

Nangle, E. J., Gardner, D. S., Metzger, J. D., Street, J. R., & Danneberger, T. K. (2012). Impact of Nitrogen Source and Trinexapac-ethyl Application on Creeping Bentgrass (Agrostis stolonifera L.) Physiology under Neutral Shade, Deciduous Tree Shade, and Full Sunlit Conditions. HortScience horts, 47(7), 936-942.  https://doi.org/10.21273/HORTSCI.47.7.936

Petrella DP, Breuillin-Sessoms F, Watkins E. (2022) Layering contrasting photoselective filters improves the simulation of foliar shade. Plant Methods. Feb 8;18(1):16. doi:10.1186/s13007-022-00844-8

The impact of No Mow May on pollinator numbers and turfgrass quality

E. Nangle D. Petrella T. Morris S. Cusack

Introduction:

No Mow May is an effort to increase pollinator number and diversity in homelawns focused on not mowing a lawn through the month of May. The idea originated in the United Kingdom and gained momentum in the United States after work published in Wisconsin (Del Toro and Ribbons, 2020) (now retracted) indicated potential benefits from this practice. Creation of areas that have greater amounts of flowering has been shown to increase pollinator levels (Blau and Isaacs, 2014; Billeisen et al., 2022) alongside maintained areas but the theory that simply not mowing a lawn will have the same effect has to date been untested. The objective of this particular trial was not to evaluate pollinator diversity but rather evaluate simply pollinator numbers as well as the impact of the practice on a home lawn and there were multiple hypotheses, firstly a traditionally maintained homelawn will not see any increase in pollinator numbers, the impact on the lawn through the summer may lead to undesirable effects and finally there may be difficulty in returning the lawn to its previous condition upon completion of the period.

Materials and Methods:

The trial was carried out on three different sites, two located in Wooster OH and one located in Columbus OH. Treatments were initiated on approximately on Apr 28 when all sites were mowed to a uniform height of 3″ and marked out. Plots were set up in a randomized complete design at all three sites with four replications per sites. Treatments consisted of a variety of mowing regimes throughout the summer period including the limitation of mowing during the month of May (Table 1). Plots were 10ft x 5ft in size to allow for commercial mowing decks to pass across the surface with a 5ft border around all plots and between reps. Prior to initiation of treatments treatments were evaluated for color (1-9 scale 6=acceptable 9 = dark green 1 = brown/dead), turf density (1-9 scale 6 = acceptable 9 = no soil visible 1 = bare soil 6 =acceptable), Weed cover (percent of plot), Pollinator count (5min timed counts occuring between 12-4pm on a date prior to the trial, during the trial and at the end of the trial). Turf height was measured using a laser height measurement tool (Bosch) and this occurred at trial completion.

Mowing was resumed on June 2 (Wooster) or June 5 (Columbus) and regimes were installed in regard to how a return to a desired 3″ mowing height would occur. Mowing in Wooster used

Table 1. Treatments used during trial evaluating impact of No Mow May on pollinator numbers and turfgrass quality

Results:

Climatically it was a dry period of the year that the evaluation occurred. The monthly rainfall amounts for Columbus were 0.3″ below normal while the area was considered to be abnormally dry. This impacted turfgrass growth by limiting the amount of biomass that was accumulated. On average however in the plots that received no mowing there was a height 16″.

Wooster Maintained lawn data

Turf density and color showed some variability in Wooster on what might be considered a traditionally maintained home lawn and once conditions became warmer and drier later in the trial all plots exhibited declines in color. On the final rating date treatments 2 and 3 showed a significant loss of color (Table 2) compared to all other treatments. Density ratings were much above acceptable during the trial for all treatments until D56 after initiation when a return to mowing and increased temperature lead to a decline in turf density (Table 3).

Table 2. Daily color ratings (1-9) during evaluation of impact of No Mow May on turfgrass and pollinator numbers during Summer 2023 in Wooster, OH.

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

Table 3. Daily density ratings (1-9) during evaluation of impact of No Mow May on turfgrass and pollinator numbers during Summer 2023 in Wooster, OH

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

Not mowing had no impact on weed development and hence limited amounts of flowering could occur (Table 4).

Table 4. Daily percent weed cover ratings during evaluation of impact of No Mow May on turfgrass and pollinator numbers during Summer 2023 in Wooster, OH

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

The timed counts provided limited information and no regime or treatment provided higher levels of pollinators in this site.

Daily pollinator count numbers during evaluation of impact of No Mow May on turfgrass and pollinator numbers during Summer 2023 in Wooster, Ohio.

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

Daily color ratings (1-9) during evaluation of impact of No Mow May on turfgrass and pollinator numbers during Summer 2023 Columbus Ohio.

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

Daily density ratings (1-9) during evaluation of impact of No Mow May on turfgrass and pollinator numbers during Summer 2023 in Columbus, Ohio.

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

Daily percent weed cover ratings during evaluation of impact of No Mow May on turfgrass and pollinator numbers during Summer 2023 in Columbus, Ohio.

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

Daily pollinator count numbers during evaluation of impact of No Mow May on turfgrass and pollinator numbers during Summer 2023 in Columbus, Ohio.

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

Conclusions:

While the trial provided a range of interesting data, concerns would arise regarding the efficacy of the program. Unless wildflowers or similar are established in a lawn and premergent herbicides are not used then it is hard to see how much flower development can occur in suburban home lawns that might be maintained in this way. Further to this many weeds such as purple dead nettle and clover will flower at height of 2-3″ thus not mowing for a month seems fruitless. The lawns that had less long term maintenance did not provide dramatically high insect numbers and this was also of interest. Finally, anecdotally in the Cleveland area the day after the trial it was noted that clover flowered. Options going forward include communication with homeowners as well as understanding what homeowners wants are – as it may be that half a lawn is enough to sustain a bee population.

References:

Billeisen, T.L. Kilpatrick, L.D. Seth-Carley, D. & Brandenburg, R.L. 2022. Presence of pollinator-friendly habitat on pollinator communities in managed turfgrass systems. Int Turfgrass Soc Res J. 2022; 14: 295– 303. https://doi.org/10.1002/its2.56

Blaauw, B.R. and Isaacs, R. (2014), Flower plantings increase wild bee abundance and the pollination services provided to a pollination-dependent crop. J Appl Ecol, 51: 890-898. https://doi.org/10.1111/1365-2664.12257

Del Toro, I., & Ribbons, R. R. (2020). No Mow May lawns have higher pollinator richness and abundances: An engaged community provides floral resources for pollinators. PeerJ, 8, e10021. https://doi.org/10.7717/peerj.10021

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The annual bluegrass weevil (ABW) (Listronotus maculicollis) has been a major pest of short-mown turf in the northeastern U.S., and it has recently spread to most areas in Ohio. This pest has been difficult to control due to the development of insecticide resistance and the occurrence of 2-3 generations per year with increasing asynchrony of stages during the growing season. Historically, ABW was only considered to be a threat to the annual bluegrass (Poa annua), but recently it has also been reported to cause significant damage to the creeping bentgrass (Agrostis stolonifera) in various regions, although ABW previously showed preference of the annual bluegrass. The question arises that whether the scenario of ABW problems in annual bluegrass would occur in creeping bentgrass, or to say, whether ABW damage levels in creeping bentgrass would be parallel to those in annual bluegrass, and if reducing annual bluegrass coverage would alleviate the problem.

To address these questions, we plan to test the ABW damage and populations in different creeping bentgrass/annual bluegrass mixture ratios, starting at annual bluegrass% of approximately 15%, 50% and 85%. ABW adults will be caged in the center of each plot to lay eggs and develop. The number of ABWs at different growing stages will be assessed to determine ABW densities and the developmental rate. Meanwhile, grass damage levels and mixture ratios will be monitored over time. There will be four blocks for each treatment, arranged in a randomized complete block design. Each plot measures 4 ft width by 4 ft length, with 4 ft buffer between adjacent plots.2023 Turf field day presentation plot map

Wetting Agents

Tyler Carr

Assistant Professor and Turfgrass Extension Specialist

Introduction:

Wetting agents are commonly used to increase moisture uniformity and mitigate the effects of localized dry spot in sand-based rootzones. New wetting agents are routinely developed and tested to ensure efficacy and limited phytotoxicity.

Materials and Methods:

This experiment was initiated on July 12, 2023 on a newly-established sand-based putting green consisting of ‘Pure Distinction’ creeping bentgrass. Fourteen experimental wetting agents and an untreated control treatment were applied in seperate plots at a rate of 6 fl oz/1000 square feet in a carrier volume of 2 gallons/1000 square feet. Within one hour of application, 0.25 inches of water was applied to the experimental area.

The wetting agents will be reapplied on 21-day intervals until five applications have been made (applications on days 0, 21, 42, 63, and 84). Irrigation will be applied at 50% of the normal rate for weeks 6-8 so treatments can be evaluated across a range of irrigation regimes.

Evaluations:

• Volumetric water content (VWC) every 14 days at 1.5 and 4.8 inches
  • 9 measurements per plot to assess soil moisture uniformity
• Phytoxicity evaluated 2 and 7 days after treatment (DAT) application using dark green color index (DGCI), a metric of turfgrass color

Results:

Soil moisture:

• Treatments did not differ in VWC 14 days after the original application
• Repeated applications are likely necessary to elucidate treatment effects

Phytoxicity:

• Treatments differed in DGCI 2 DAT, with many treatments significantly different than the untreated control (Figure 1). This implies that some phytoxicity was present in those treatments. All phytoxic effects were alleviated by 7 DAT.

Figure 1. Dark green color index values for 14 experimental wetting agents and an untreated control two days after treatment application on a sand-based ‘Pure Distinction’ creeping bentgrass putting green in Columbus, OH. Greater values indicate darker green turfgrass, and bars represent the least significant difference for detecting treatment differences (P ≤ 0.05)

Conclusions:

Evidence from previous research indicates that season-long wetting agent programs are beneficial in alleviating localized dry spot and increasing moisture uniformity on sand-based putting greens. While this study is only at its infancy, monitoring a wetting agent program throughout the season will help companies identify products that perform best in Ohio.

Biostimulants and Drought Tolerance – what have we learned over the two years.

E.J. Nangle T. Morris, S. Cusack and D.P. Petrella

Introduction:

The use of biostimulants in turfgrass management is becoming more critical to the success of turfgrass managers as environmental stresses increase and limitations are continulaly expanded on what can be used in golf course settings. The consistency of the results obtained can however leave turfgrass managers with pause for concern . Issues such as variations in soil types, site specificity and variations in organic matter content, unclear pathways of plant uptake are components of the products that can impact the efficacy of these products. Results have been successful where products have had combinations of nitrogen included in the product and also in laboratory settings indicating there is potential for their use – however field applications have been where the conundrum arises.

One area that is going to be continually a concern for turfgrass managers is the ability to manage turfgrass surfaces with limited levels of moisture to sustain high quality turfgrass surfaces . Products such as wetting agents can help with soil issues that might arise but options for drought tolerance include breeding and potentially use of C4 grass species if conditions continue to deteriorate. The objective of this trial was to evaluate the use of a group of products that are commonly called biostimulants which offer potential solutions in regards to plant hormone changes, stress tolerances and a range of other issues. To compare these products against each other is a regular occurrence but evaluation of these products agaisnt an alternative approach such as the use of Urea also is required based on budget and potential return on investment.

Materials and Methods:

This trial was initiated in its second year at the Waterman Farm in Columbus Ohio on June 8th 2023 on a research green surface that contained a mixed stand of annual bluegrass Poa annua and creeping bentgrass Agrostis stolonifera. The green is mowed at 0.145″ 4x per week with clippings collected and received preventative applications of insecticides and fungicides. Applications were made on June 23rd, July 5th and July 19th using a back pack CO2 sprayer at high label rates for all products (Table 1).

Table 1. Treatments and rates for products used in evaluation of biostimulants for drought tolerance during Summer 2023 in Columbus, OH.

The treatments were replicated four times and laid out in a randomized complete block design (Figure 1). Drought stress was initiated on July 12 with the construction of a framed rainout shelter that was covered with polyethylene liner which was opened on the north and south end to allow for air movement. The drought period was completed on July 24th when hand watering was returned. Turf was evaluated for quality (1-9 scale), color (1-9 scale), percent stress on the plots, normalized difference vegetative index and volumetric water content at 3″ depth. Treatments will be made one final time and recovery will be evaluated through August 31st 2023.

Figure 1. Plot design for trial evaluating impact of Biostimulants on drought stress, Summer 2023, Columbus OH

Results:

Color ratings indicated some minor differences initially with treatments 3,4,6 and 8 having a slightly higher color rating but 0.2 difference overall would seem to be of limited consequence. At D27 variability increased but none of the treatments provided color rankings significantly higher than the check plot (9) (Table 2).

Table 2. Daily color ratings during evaluation of biostimulants for enhancement of tolerance to drought stress in Columbus OH, Summer 2023

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

Turf quality with the exception of the final rating date was found to be acceptable for all treatments. On the final date treatment 4 provided an overall ranking that was below acceptable and across all treatments there was some decline in quality. Highest rated treatments were 1,6 and 8 for the final date (Table 3).

Table 3. Daily Quality ratings during evaluation of biostimulants for enhancement of tolerance to drought stress in Columbus OH, Summer 2023

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

NDVI values showed some variability at D15 and that pattern continued through D48 when plots were under the most drought stress. Treatment 7 provided significantly lower values along with treatment 9 and 2 on D41 while treatments 3,6 and 8 were rated significantly higher than four other treatments on that date (Table 4).

Table 4. Daily NDVI Ratings during evaluation of biostimulants for enhancement of tolerance to drought stress in Columbus OH, Summer 2023

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

Stress did not develop until D41 which was 7 days after drought was initiated and on both dates (D41 and D48) percent of stressed turf increased. Treatments of Urea att he highest rate provided plots with the lowest levels of stress and this was significantly lower than many of the other treatments. The lower rate of urea also began to show stress at D48 while plots receiving treatments 2,7 and 9(UTC) showed greater stress to the drought (Table 5).

Table 5. Daily stress ratings (% plot) during evaluation of biostimulants for enhancement of tolerance to drought stress in Columbus OH, Summer 2023

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

Conclusions:

In 2022, treatment #7 provided turf quality as high as the urea treaments but this did not happen in 2023. The additional rate of urea showed a dose response in the sense that the lower rate showed increased stress during the drought period. Recovery data will be collected and analyzed for both years to complete this study. The products used other than urea currently cannot form a stand alone program for drought stress and should only be used in combination with other agronomic practices.