Henry Rice, Graduate Research Associate

Shaohui Wu, Assistant Professor of Turfgrass Health

The session features various tactics for scouting and monitoring turfgrass pests.  In particular, participants will gain hands-on experience to practice soap flushing for surface-active insects, and soil sampling for below-ground pests. Other tools, including pitfall traps, light traps, and pheromone traps, will be demonstrated. Also, specimen identification will be followed for common turfgrass pests detected from these methods.

Introduction:

Increased traffic on community sports fields diminishes turfgrass coverage. To address this issue, this project aims to find the optimal combination of mowing height and nitrogen rate for tall fescue and Kentucky bluegrass under traffic. These turfgrasses were selected since Kentucky bluegrass which is the most commonly used turfgrass for recreational sports fields in Ohio, while tall fescue offers a lower-input alternative.

This experiment will test three mowing heights and six fertilizer rates over two years, 2024 and 2025. By fine-tuning management practices, we aim to equip sports field mangers with the tools to maintain high-quality turfgrass, despite unpredictable and often excessive use.

Optimizing mowing height and nitrogen rate is crucial as these are controllable factors in an environment where traffic levels are often beyond the sports field manager’s control. This research will help allocate resources efficiently by determining the most cost-effective mowing and fertilization strategies for different turfgrass conditions.

Objective: Determine the effect of mowing height and nitrogen fertilizer rate on the simulated athletic field traffic tolerance of (1) tall fescue and (2) Kentucky bluegrass.

Materials and Methods:

• Mowing Program
  • Mowing occurs with a walk-behind rotary mower and clippings are returned
  • 5 inch mowing height: mowed on Monday, Wednesday, and Friday
  • 5 inch mowing height: mowed on Monday and Friday
  • 5 inch mowing height: mowed on Monday
• Fertilizer Program
  • 0, 1, 2, 3, 4, and 5 lb N/1000ft² are applied every two weeks (June-October) and watered in directly afterwards
  • Granular fertilizer was applied in the form of ammonium sulfate (21-0-0)
• Traffic Program
  • Traffic will occur August through October for 10 weeks using a modified Baldree traffic simulator (Toro ProCore 648)
  • These traffic events will occur 3x/week on Tuesday, Wednesday, and Thursday
• Data Collection
  • Data will be collected 1x/week for ten weeks starting in August
  • Turfgrass coverage will be assessed weekly using digital image analysis
  • Surface hardness will be collected weekly using the Clegg Impact Soil Tester (2.25 kg)
  • Rotational resistance will be assessed weekly using a Shear Vane
  • Soil moisture and temperature sensors have been installed at three different points throughout each trial area to continuously monitor these parameters

Expected Results:

The objective of this project is to find the optimum combination of mowing heights and nitrogen rate under traffic stress. It is expected that higher amounts of nitrogen will increase green cover, though we do anticipate that there will be a point where additional fertilizer will not improve the quality of the turfgrass. We also expect that the optimal nitrogen rate for traffic tolerance may vary depending on mowing height. Additionally, each species may require different nitrogen rate and mowing height combinations for optimal performance. Overall, we aim to find the best nitrogen rate and mowing height combinations so that sports field managers can allocate their resources efficiently in different conditions.

Results from 2024:

From the data collected in 2024, we saw that on both trials, lower mowing heights resulted in greater coverage. Mowing height was also the only factor which had an impact on shear vane and Clegg results, with lower mowing heights providing greater rotational resistance and hardness. On tall fescue, there was no statistical difference between 3lbs and 5lbs.

Shaohui Wu, Ph.D., Assistant Professor of Turfgrass Health

This talk will cover general cultural practices that can be incorporated into the IPM program for controlling turfgrass pests and diseases.  These include:

• Benefits of aeration & dethatching for reducing diseases and thatch-feeding pests
• Mowing – removal of clippings (Yes/No?)
• Time and frequency of irrigation in relation to pest and disease pressures
• Turfgrass selection for host plant resistance
• Top dressing reducing thatch and diseases
• Fertilization affecting pest and disease occurrence

Henry Rice, Graduate Research Associate

Shaohui Wu, Ph.D., Assistant Professor of Turfgrass Health

Goal of study: To evaluate the susceptibility of various creeping bentgrass cultivars to annual bluegrass weevil.

CBG cultivars vs. ABW Plot Map

CBG cultivars vs. ABW Results

• Turf plugs were taken and repotted in the greenhouse. Three pairs of ABW adults were caged per pot to allow for oviposition for one week. Larve were extracted using saline solution at 3-4 weeks after adult removal.
• Pure distinction was the only cultivar assessed with ABW larval densities reaching typical action thresholds (30-50 larvae per square foot).
• More replicates will be conducted in Spring 2026.
• Selected commercial cultivars will be compared with experimental lines at Rutgers University for breeding potential against ABW.

Brenda Medina-Privatt, Florence Sessoms, Dominic Petrella, Steven Lyon, David Gardner, Cale Bigelow, Jada Powlen, Ed Nangle

Introduction

Results

Image of perennial ryegrass pots two weeks after soy flour application.

Figure of mean clipping biomass accumulation as effected by soy flour treatments applied to perennial ryegrass growing on sand or field soil

Current thoughts / Future work

At the second week of application, NDVI results indicate a stronger vegetative response from soy flour treatments compared to the pelletized forms. The 1 lb N soy flour treatment showed the highest NDVI (0.48), followed closely by the 0.75 lb rate (0.46), suggesting effective and readily available nitrogen release. In contrast, both coated and uncoated pellets resulted in lower NDVI values (0.35–0.40), with the 1 lb coated pellets underperforming even the control. These early results align with expectations for soy flour as a faster-releasing nitrogen source, while the pellets, particularly the coated form, may require more time to mineralize and become plant-available.

Project Summary

Irrigation system auditing is critical for plant health and water conservation in turfgrass management. Auditing involves placing catch cans in a pre-determined pattern across a turfgrass surface, running the system and collecting water, measuring the amount of water collected, and evaluating how uniformly the water was distributed. However, this practice is labor intensive, time-consuming, and prone to human error. Because of this, few turfgrass managers or homeowners routinely audit their irrigation systems, leading to both over- and under-watering. We are proposing to modernize the auditing process to increase irrigation system efficiency, save water, and help turfgrass managers maintain healthier turfgrass. To do this, we will utilize a drone-mounted thermal camera to monitor surface temperature before, during, and after an irrigation cycle is run. Utilizing Geographic Information System (GIS) software, we will create raster maps of surface temperature contrasts to determine where more/less water is being applied based on rates of surface warming. Ground-truthing data using the traditional catch can method and soil moisture data will be collected for validation. Experiments will be scaled from examination of single irrigation sprinklers to square test plots with sprinklers on each corner, and finally to the level of a golf course green or fairway. We envision the ability to quickly diagnose sprinklers that need adjustments to increase irrigation uniformity. This method will provide a much-needed update to the auditing process, and will provide an affordable, accessible, and efficient tool that maximizes turfgrass health, improves sports surface playability, and conserves water.

An example of an athletic field in which irrigation does not apply water uniformly (credit: Irrigation Association).

An example of an irrigation audit using the catch can method (credit D. Petrella).

Objectives

1. Modernize irrigation auditing methods using drone mounted thermal cameras
2. Perform a cost-benefit analysis of thermal camera based-auditing compared to traditional methods

Experiment 1 – Develop and validate methods

At the Ohio Turfgrass Foundation (OTF) Research Center at The Waterman Agricultural and Natural Resources Laboratory in Columbus Ohio we will develop thermal surveying methods using an Autel Robotics EVO II Dual 640T RTK V3 thermal drone. We will capture ground control point data to enhance location accuracy for all experiments and will use flight planning software for repeatability. In all objective 1 experiments we will analyze spatial variability in thermal data using raster layers in GIS software such as ArcGIS, and we will examine visualization using Autel software and 3rd party apps such as SkyeBrowse.

During all experiments in Objective 1, the data collected by the drone will be compared to ground truth data provided by soil moisture meters and catch cans to see how well this method correlates to standard auditing tools. We will also create raster maps using soil moisture data and catch can volumes to overlay with drone collected data to examine accuracy and sensitivity of our method.

Example of experimental block captured from drone. (Credit: VanLandingham)

Example of thermal image captured from drone while irrigation is being applied. (Credit: VanLandingham)

Experiment 2 – Develop a scaled-up proof of concept:

Once methods have been established, we will move to a replicated field plot experiment at the OTF Center as a means to scale up. Experimental blocks (3,600 ft²) will be set up with 4 irrigation heads that are currently set to 90° arcs and we expect to begin this experiment in late summer of year 1. Each block will contain one of the following treatments to a single irrigation sprinkler: 1) 120° arc, 2) clogged nozzle, 3) incorrect nozzle, 4) no head rotation, or 5) sprinkler set to “off”. These blocks will be replicated three times across both fairway and greens height turfgrass with a creeping bentgrass/Poa annua mix.

Experiment 3 – Validate methods on golf courses in Ohio:

After methods have been validated in field plot experiments, the final step of objective 1 is to take the methods out to golf courses near Columbus Ohio in year 2. We will work with 3 local golf courses, each golf course will be considered a whole plot replicate, and we will specifically work with golf courses who have not audited their irrigation system within 3-5 years. At each golf course we will audit 3 greens and 3 fairways using traditional catch can methods, using soil moisture sensors, and using the thermal drone method we have developed. We will perform each audit at each golf course two times in year 2. We will not repair or fix sprinklers at the golf courses during this experiment. For experiment 3, we will collect data on the amount of time (in work hours) it takes to utilize our methods and traditional methods. We will specifically perform this at different golf courses to help take into account different soil types, how surroundings such as shade impact temperature data, and how different turfgrass species mixtures may impact the data we collect.

Brian Miller, David Gardner, Alyssa Essman, & Tyler Carr 

Introduction 

Weeds, such as white clover, dandelion, crabgrass, and goosegrass, are major challenges in turfgrass management, competing with turfgrass for essential resources and reducing overall turfgrass quality. The short- and long-term impacts of autonomous mowing on weed dynamics and turfgrass competition are not well understood. Additionally, the use of autonomous mowers during turfgrass establishment and how it may differ from standard turfgrass management practices is not clear. There are two separate experiments, one evaluating perennial broadleaf weeds such as white clover and dandelion. The other experiment assesses summer annual grassy weeds such as crabgrass and goosegrass. 

The objective of these experiments is to evaluate the effects of autonomous and conventional rotary mowing practices on both perennial broadleaf and summer annual grassy weeds. 

Materials and Methods 

Two distinct experimental areas were selected at the Ohio Turfgrass Foundation Research & Education Facility in Columbus, Ohio to carry out the experiment. The areas were selected due to already having established weed species of interest. Both areas are a 2 × 2 randomized complete block design with 4 replications of each treatment combination.  

Factor 1: Mower type 

• Autonomous (550H EPOS, Husqvarna) 

• Conventional (HRN, Honda) 

Factor 2: Mowing height 

• 2.0 in  

• 3.5 in 

2 lb N 1000 ft-2 is applied to each experimental area, split between spring and fall 

*Autonomous areas are mowed every two days; clippings are not collected. Conventional areas are mowed to comply with the rule of thirds. Clippings are returned to the surface.  

Mowing began April 24, 2025, and treatments will continue through November 2025. The same treatments will be replicated from April 2026 through November 2026. 

• Turf quality is visually assessed once every two weeks to compare the differences between different heights of cut and frequencies. 

• The health and vigor of the turf is measured once every two weeks through using the normalized difference vegetation index (NDVI) to help eliminate bias and subjectiveness from the visual turf quality rating. 

• Turf density is visually assessed once every two weeks to compare the differences between different heights of cut and frequencies. 

• Shoot density is determined by manually counting the shoots from two randomly selected subsamples in order to assess treatment effects on turfgrass density.  

• Percent weed coverage is visually assed once every two weeks to compare the differences between heights of cut and frequencies.  

• Weeds of interest are counted once per month for the broadleaf weeds experimental area and once every two weeks for grassy weeds experimental area to track the population changes over the course of treatments. 

• A seedbank study is conducted once at treatment initiation and once at the end of each year to understand how the seedbank is affected by mowing practices. 

The project will be conducted for 2 growing seasons, ending in November of 2026. It is expected that through frequent autonomous mowing, turf density will increase, leading to reduced weed populations compared to conventional rotary mowing practices. We also hypothesize that autonomous mowing will suppress seedhead production in summer annual grassy weeds, such as crabgrass and goosegrass which may reduce the weed seedbank more effectively than conventional rotary mowing. Up to this point in the study, we have seen a reduced grassy weed population in the autonomously mowed areas at both 2 in and 3.5 in heights of cut.