Virginia Turfgrass Journal - March / April 2024

Plus, Considerations with Biostimulants for Turfgrass Management

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or two years you have given me the privilege and responsibility to assist you and your business to be the best it can possibly be. With this responsibility as your President of the Virginia Turfgrass Council (VTC) and the Virginia Turfgrass Council Environmental Institute (VTC-EI) we have accomplished many goals to strengthen your ability to do business.

On many occasions your belief in the VTC-EI has allowed us to represent your interest at Virginia Department of Agriculture meetings. We represented you and your concerns to the Honorable Matt Lohr, Secretary of Agriculture and Forestry, regarding certified pesticide applicator concerns. We had the ability to meet with Commissioner Joseph Guthrie to advocate your concerns regarding difficulty associated with online pesticide applications and testing. With these efforts and the continued collaboration with VDACS many of these issues have been solved.

It was one of our main goals to develop a free online membership service for you and your team to have access to recertification in both fertilizer and pesticides. What a great benefit of membership for you or your business to update your teams’ credentials on your schedule at any time you feel the need to do so.

The VTC-EI has branched out to represent you in the community. By developing community service projects with leaders in your community we have cemented our industry’s commitment to sound, science-based practices. These practices and services you provide protect the environment but deliver spectacular green spaces.

With these accomplishments, it’s time for me to pass along the torch to the next VTC / VTC-EI President. The passing of the torch allows fresh views and direction to better our membership and industry. It is with great pleasure that I pass the torch to Wes Bray, owner of Lawns and Gardens Plus. Wes is a Distinguished Professional of the Year recipient from the Virginia Nursery and Landscape Association, a Presidential Award recipient from the Virginia Turfgrass Council and key component of the “Come to the Bay” program and community service project. I wish continued success to our membership, confidence in Wes Bray’s guidance and the continued dedication of the entire VTC / VTC-EI Board of Directors.

Respectfully submitted,

Phil Bailey

Past President of the VTC/VTC-EI

VTC DIRECTORS

Sam Burris

Jack Findling

Ray Funkhouser

Richard Linsday

Bruce Sheppard

T.J. Skirsky

Craig Zeigler

VTC ADVISORY MEMBERS OF THE BOARD

Mike Goatley, Ph.D. (Chair)

Shawn Askew, Ph.D.

Alejandro Del Pozo-Valdiva, Ph.D.

Jeffrey Derr, Ph.D.

David McCall Ph.D.

Dan Sandor, Ph.D.

Cynthia Smith, Ph.D.

EXECUTIVE DIRECTOR / DIRECTOR OF PROGRAMS

Tom Tracy, Ph.D. (757) 464-1004

VIRGINIA TURFGRASS FOUNDATION

Brandyn Baty (757) 585-3058

Phil Bailey, CGCS VTC Past President

Diamond Members and Suppliers MAKE A DIFFERENCE!

Iam taking chance of mistakenly omitting a company but am going forward and recognizing our Diamond Members and several Suppliers. Each of the persons and companies have significantly worked with us in our service to the Green Industry.

DIAMOND MEMBERS TruGreen

This company’s financial assistance enables our strong legislative outreach. Jeff Fedorchak of TruGreen is a major supporter! Many pieces of legislation were directed against us during the current session of the General Assembly. TruGreen enabled us to modify or eliminate those items. Also, over the past years, TruGreen has provided us with 50,000 packets of Flowering Pollinator Seeds to distribute to legislators and other persons whose decisions affect our industry. Next on the agenda is developing a portable urban runoff demonstration unit that will clearly show the value of turfgrass.

Lawns And Gardens Plus

It is not an overstatement to assert that Come to the Bay and our Virginia Beach Service Projects are only possible because of Wes Bray’s very generous support. His company provides financial resources and during each of our Service Projects the entire crew has spent hours preparing the sites and working diligently on the day of each event.

Landscape Supply

The vast support provided by Landscape Supply, a Diamond Member, is detailed below under Suppliers.

Agronomic Lawn Management

Board Member

Craig Zeigler has provided extensive financial assistance. They are not only Diamond Members but ALM also is a top-tier sponsor of many of our events.

WeedMan

WeedMan’s contributions go far beyond providing finances. Bruce Sheppard is on our Board of Directors and serves as chair of the Legislative Committee. He provides much needed direction!

SUPPLIERS

Landscape Supply

The support provided by Landscape Supply, a Diamond Member, is difficult to place in the space allowed. Allow me to mention two: One, they provided twenty of the coir logs needed for the recent service project (the logs were huge – about 18" in diameter and were about 8' to 10' long), delivering them on a Landscape Supply flatbed truck on the morning of the project; and two, they brought the VTC in as a partner in their highly successful spring pesticide recertification webinar. That event attracts over 900 attendees.

McGill Compost

Each of our Service Projects required compost. Not only did McGill provide what we needed but David Holcomb regularly donated his time and muscle on the day of the projects.

Advanced Turf Solutions

Through T.J. Skirsky, VTC Board Member and long-time supporter of the industry, Advanced Turf Solutions designed our Environmental Institute logo.

Trinity Turf

We needed bags of seed for our Legislative Seed Distribution. Kurt Fellenstein not only provided 300 custom bags of fescue seed, he also delivered those seeds to the General Assembly Building on the day of distribution AND when we needed 30 more, he provided and delivered them a week later.

SiteOne Landscape Supply

For over a decade, Barry Kessler has been a tremendous supporter of our industry. Recently, he provided the remaining coir logs needed for the recent service project. He also provides space at the local branch to promote the VTC and the Environmental Institute.

We are thriving and serving our great industry because of our membership and the persons and companies listed above. Please forgive me if I mistakenly omitted you or your company.

Tom Tracy, Ph.D. VTC Executive Director

Virginia Tech Turf Team

Shawn D. Askew, Ph.D. Virginia Tech

435 Old Glade Road Blacksburg, VA 24061

540-231-5807 askew@vt.edu

Alejandro Del Pozo-Valdiva, Ph.D. Virginia Tech

Hampton Roads Agricultural Research Station

1444 Diamond Springs Rd. Virginia Beach, VA 23455 757-363-3900 adelpozo@vt.edu

Jeffrey F. Derr, Ph.D. Virginia Tech

Hampton Roads Agricultural Research Station

1444 Diamond Springs Rd. Virginia Beach, VA 23455 757-363-3912 jderr@vt.edu

Mike Goatley Jr., Ph.D. Virginia Tech

420 Smyth Hall Blacksburg, VA 24061

540-231-2951

goatley@vt.edu

David McCall, Ph.D. Virginia Tech

435 Old Glade Road Blacksburg, VA 24061

540-231-9598

dsmccall@vt.edu

Dan Sandor, Ph.D. Virginia Tech

170 Drillfield Dr.

411 Price Hall Blacksburg, VA 24061

540-231-9775

dsandor@vt.edu

WITH SUPPORT FROM:

Thomas P. Kuhar, Ph.D. Virginia Tech

Dept. of Entomology

216 Price Hall

170 Drillfield Drive Blacksburg, VA 24061

540-231-6129

tkuhar@vt.edu

Over 900 Persons

Recertified in Five States and the District of Columbia

Wewere honored when W.S. Connelly & Co. invited the Virginia Turfgrass Council to be a part of their highly successful spring pesticide recertification webinars. The over 900 persons who chose to attend either the March 13 or March 14 webinar received pesticide credit from one or more of the following: Virginia, Delaware, Pennsylvania, North Carolina, West Virginia, and the District of Columbia.

As usual, the webinars included the highly relevant and educational W.S. Connelly Scholarship Competition. Nine graduate students did a fantastic job of presenting their research in the fifteen minutes allowed for each one.

Here are the winners

1ST PLACE

Elisabeth Kitchin

Pixels to Pathogens: Utilizing Machine Learning for Disease Detection and Quantification

2ND PLACE

Ava Veith

Spring Dead Spot and Winter Injury Impacts on Athletic Field Playability and Safety

3RD PLACE

Caleb Henderson

The Full Monty: A Case Study of Precision Spring Dead Spot Management across an Entire Golf Course

PEOPLE’S CHOICE AWARD

Elisabeth Kitchin

Pixels to Pathogens: Utilizing Machine Learning for Disease Detection and Quantification

Make plans to attend this event next spring. In addition to adding states giving credit for attendees, we intend to offer CEUs from the GCSAA, SFMA, and others.

These City of Norfolk employees are two of the 900 persons attending the pesticide recertification webinar via Zoom.

Legislative UPDATE 2024 BOARD MEMBERS

The2024 General Assembly session was very important for our industry. We were particularly concerned about two bills: House Bill 320 allows non-licensed persons to apply pesticides on government property and House Bill 644 (same as Senate Bill 305) which allows localities to restrict gas-powered leaf blowers. The first one passed; the second was carried over to 2025.

House Bill 320 seeks to control invasive weeds – the goal is noble and one we totally support. We do not agree with the methods that piece of legislation uses to achieve that goal. Certified Pesticide Applicators are trained, pass a rigorous examination, attend regular recertification classes, and work for a licensed, insured company. Allowing volunteers to apply the same products in public areas creates a two-tiered system: One for industry persons who work diligently to obtain – and to maintain –their license and one for volunteers. Governor Youngkin is expected to sign the bill into law.

Please welcome our new VTC President and Vice President!

Wes Bray is our new President, and Harris Wheeler is now Vice President. Wes and Harris have both been tremendous supporters of our organization and we’re excited to welcome them into these leadership roles!

Online RECERTIFICATION

We are offering another member benefit: free on-line/on-demand pesticide and fertilizer recertification.

These classes are totally free for members, meet industry needs, and may be accessed any time day or night.

Members needing Virginia

3B or 60 recertification or credits for their Certified Fertilizer Applicator license can go to https://vaturf.org/on-line-recertification/ to sign up.

M Highlights from COME TO THE BAY

any hours of preparatory work and extensive planning came to fruition during the week of January 22 with the 2024 Come to the Bay. That event started on Monday with a service project at the Virginia Aquarium and Marine Science Center – that project was only possible because of tremendous support from Virginia Beach City Public Schools (VBCPS). The following three days were filled with classes and networking opportunities at the Hampton Roads AREC.

The service project met two major needs: establishing a native planting around a newly installed demonstration pond and controlling erosion caused by stormwater surging into the tidal inlets. Both needs were met by industry and public schools working together. Lawns and Gardens Plus provided much of the labor and materials needed to prepare for planting around the pond; VBCPS students at the Career and Technical Center grew many of the plants in their greenhouses. Other plants were provided by Wild Works of Whimsy. Two students enrolled in the environmental studies program worked with architects to design the planting. Both industry volunteers and students from the Center worked to install these plants!

Erosion controlling coir logs were the mainstay of protecting the site from stormwater surges. These logs were huge – each was approximately 18" wide and 8' long. They were also heavy! Landscape Supply donated the logs. They delivered them on Monday morning and even provided a forklift to get them off the flatbed trailer. We needed additional logs and they were graciously provided by SiteOne. VBCPS students who were also enrolled in the environmental studies program worked with another architecture firm to design proper placement of the logs. On the day of the service project, they carried the logs down the embankment and worked with industry volunteers to firmly attach them to the soil.

Afterwards, all the volunteers gathered for lunch and listened to presentations by the students who designed and installed the service project’s plantings and erosion control. Bill’s Landscaping & Designs provided tickets for attendees who wanted to visit the aquarium. Agronomic Lawn Management and Lawns & Gardens Plus, primary sponsors of Come to the Bay, provided lunch.

For the first time in its history, Come to the Bay’s classes were held at the Hampton Roads AREC, Virginia Tech’s Virginia Beach facility. Being at that location allowed us to showcase the

great work being done there for our industry. Our attendance was more than the building could hold so SiteOne and Land & Coates sponsored a large tent that was set next to the main entrance of the AREC. Members who attended the classes got free pesticide and fertilizer certification and recertification credits. Lunch on each of the three days of classes was provided by Agronomic Lawn Management and Lawns & Gardens Plus.

Tremendous networking happened between classes and during lunch – discussing business opportunities and the challenging information presented by each speaker. Karen Duhring of the Virginia Institute of Marine Science was the keynote speaker. Her insights into business opportunities in establishing and maintaining living shorelines were very timely and possibly caused more than one attendee to plan on adding that service to their customers.

Volunteers and sponsors made the 2024 Come to the Bay conference a success. We are currently making plans for next year’s event. Please contact the VTC or the VTC Environmental Institute if you are able to help make the 2025 even better.

Agronomic Lawn Management

Bill’s Landscaping and Design

Land and Coates

Landscape Supply

Lawns & Gardens Plus

McGill Compost

SiteOne Landscape Supply

Virginia Aquarium and Marine Science Center

Virginia Beach City Public Schools

Wild Works of Whimsey

On Seed DISTRIBUTION

Tuesday, February 13th, we distributed 300 Custom Blended Fescue Seed bags at the Virginia General Assembly. Those seed bags were generously provided and delivered by Kurt Fellenstein of Trinity Turf. Phil Bailey and Beck Stanley made all the arrangements with Capitol Police for us to bring seeds to the loading dock We also distributed the same number of Flowering Pollinator Seed Packets to members of the General Assembly.

This is yet another great opportunity VTC-EI provides to make connections with policymakers and represent the interests of VTC members. Thank you to all who made this event possible!

Security Person (L), Phil Bailey, Board Member (M) and Craig Zeigler, Board Member (R) prepare to go to the General Assembly building

Sam Burris, Board Member (L) distributing bags of grass seed

Kurt Fellensteir and Sam Burris

Foreground: Phil Bailey, President (L) and Beck Stanley (R) display packs of seed provided by Trinity Turf. Background: Craig Zeigler, Board Member (L) and Wes Bray, Board Member (R)

Wes Bray, Board Member (L) and Craig Zeigler, Board Member (R) making a seed delivery.

Wagons were a big help with carrying the seeds

The 2024 ROAD SHOW

first ever Virginia Tech Road Show, hosted by the Virginia Turfgrass Council, was held in Fredericksburg on February 21. Over 85 persons attended this inaugural event. Many came to interact with the Virginia Tech turf team and to meet requirements for pesticide recertification. During lunch, attendees took advantage of the location and enjoyed exploring the Fredericksburg Nationals Stadium, the Road Show’s location.

Stadium Entrance

David McCall, Ph.D.

Dan Sandor, Ph.D.

Attendees

Upcoming Events

June 27, 2024

Hampton Roads AREC Turfgrass Field Day

Virginia Beach, VA

August 26 – 27, 2024

Virginia Tech Turfgrass Field Day

Blacksburg, VA

December 3 – 5, 2024

Lawn & Landscape Short Course

Henrico, VA

Charles Fultz Stadium Workers Mike Goatley, Ph.D.

By Mike Fidanza, Ph.D. Professor of Plant and Soil Science, Penn State Berks Campus; Reading, PA (maf100@psu.edu)

The Considerations with Biostimulants for Turfgrass Management

term “biostimulant” has been misunderstood, misused, or misplaced as a potential “miracle cure” in the turfgrass industry, and biostimulant products were often dismissed as “snake oil” or “foo-foo juice” (e.g., sarcastic reference to the mythical foo-foo tree). Some biostimulant products make performance claims substantiated with scientific research, while other products lack direct evidence of their actual benefit.

Dr. Richard Schmidt (Emeritus Professor at Virginia Tech; Blacksburg, VA; and Penn State alum) is considered the pioneer of biostimulant research in turfgrass science. Dr. Schmidt defined biostimulants as follows: “Biostimulants are organic materials that when applied in small or minute quantities enhance plant growth and development.” The use of the word “minute” in this definition is intended to differentiate the fact that these substances, compared to traditional nutrients and/or soil amendments, elicited a measurable and beneficial response at much lower application rates. In his early work, Dr. Schmidt considered the plant biostimulant effect was attributed to a hormonal response and the plant protection effect against abiotic stress as attributed to antioxidant production, and both of those effects made possible from low concentrations of exogenous applications. Dr. Schmidt also used the term “metabolic enhancers,” but the important distinction was that something positive was happening to the plant beyond what mineral nutrition supplied.

More recently, plant biostimulant is defined as “any substance or microorganism applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance, and/or crop quality traits, regardless of nutrient content.” The term “plant biostimulant” often is used to describe the various categories of compounds and substances used in these products: plant growth hormones (e.g., abscisic acid, auxins, cytokinins, gibberellic acid, etc.), microorganisms (e.g., Bacillus spp., Trichoderma spp., mycorrhizae, etc.), amino acids, humic and fulvic acids, plant defenseactivating substances, plant growth-promoting compounds, vitamins, pigments and oils, soil amendments and soil conditioners, composts and compost teas, and more.

The European Biostimulant Industry Council (EBIC; https:// biostimulants.eu) defines biostimulants as: “Agricultural biostimulants include diverse formulations of compounds, substances, and other products that are applied to plants or soils to regulate and enhance the crop’s physiological processes, thus making them more efficient; biostimulants act on plant physiology through different pathways than nutrients to improve crop vigor, yields, quality and post-harvest shelf life/conservation.” The EBIC also has a functional definition of plant biostimulants as follows: “A material which contains substance(s) and/or microorganisms whose function, when applied to plants or the rhizosphere, is to stimulate natural processes to benefit nutrient uptake, nutrient efficiency, tolerance to abiotic stress, and/or crop quality, independently of its nutrient content.” Of note, the EBIC’s functional definition expands beyond the ‘plant’ to also include the ‘soil’ (e.g., rhizosphere).

The Association of American Plant Food Control Officials (AAPFCO; https://aapfco.org) defines biostimulants as: “Any substance or compound other than primary (e.g., N, P, and K), secondary (e.g., Ca, Mg, S), and microplant nutrients (e.g., Fe, Cu, etc.), that can be demonstrated by scientific research to be beneficial to one or more plant species when applied exogenously; …a substance or material, with the exception of nutrients or pesticides, which has the capacity to beneficially modify plant growth.” Of note, the ASPFCO definition of biostimulants refers to the term “beneficial substance.”

Biostimulants are often categorized by “what they are” (e.g., how are these substances or compounds or component materials described chemically or physically?) and “what they do” (e.g., how do these substances or compounds benefit the turfgrass plant or the turfgrass soil/rootzone?). The turfgrass practitioner and stakeholder would benefit from knowing not only what a biostimulant is actually composed of, but how those commercially available biostimulant products benefit turfgrass management programs. Therefore, a proposed classification method or strategy for listing biostimulants in turfgrass is presented in Table 1 Overall, biostimulants are listed as primarily targeting the plant or soil/rhizosphere, then further organized by category to describe their composition, followed-by active or functional ingredients (e.g., compounds, substances, other descriptive terms) listed within each category. Examples of common names for biostimulant products are listed for each category.

I. Phytohormones

Plant hormones or phytohormones are considered chemical messengers in plants. They are referred to as ‘signal molecules’ that occur in very low concentrations, and are vital to plant growth and development, and regulation and function of many physiological processes. The most common phytohormones utilized as plant biostimulants are abscisic acid, auxins, cytokinins, ethylene, and gibberellic acid.

Abscisic acid is associated with water regulation in plants and is associated with the plant’s ability to mitigate abiotic stress from drought, salinity and temperature. Auxin is responsible for phototropism (e.g., shoots growing upward, toward the light) and gravitropism (e.g., roots growing downward

into the soil). Indole-3-acetic acid (IAA) is the most common naturally occurring auxin and included as the auxin component of many biostimulant products to promote root viability and drought tolerance. Cytokinins are involved with plant growth and development and stress-response processes, and in particular with cell division and delaying of leaf senescence (e.g., plant senescence is the process of aging in plants; plants have both stress-induced and age-related developmental aging). This delay of leaf senescence or “stay green” effect is a plant stress response in which cytokinins inhibit the action of senescence-inducing enzymes, slowing the degradation of chlorophyll, and maintaining photosynthetic rates and root viability. An example of a commonly used biostimulant product in this category is seaweed extract, also referred to as seaplant or kelp. Gibberellic acid controls important plant growth functions such as cell elongation and stem growth, seed germination, flower development, and flowering time. While abscisic acid, auxin, cytokinin, and gibberellic acid exist in the plant in liquid form, ethylene is a gaseous phytohormone that regulates plant growth (e.g., the development of leaves, flowers, and fruits), senescence, response to environmental stresses (e.g., heat and freezing stresses), and often interacts with other phytohormones.

II. Biopolymers, protein hydrolysates, and other N-containing compounds

Examples of compounds in this category include amino acids, and they are considered the “building blocks” for proteins, enzymes, nucleic acids, antioxidants, and other secondary compounds. The L-form of amino acids are assimilated by plants, and these L-amino acids and short-chain peptides are reported to increase plant N uptake, increase root mass, activate natural defense mechanisms, and enhance photosynthesis.

III. Other botanical or synthetic bioactive compounds

This is a “placeholder” category for plant-directed compounds not yet described or fully understood, or for compounds that do not fit the description of the other categories. An example of an organic compound in his category is acibenzolar-S-methyl, which is a synthetic analog of salicylic acid and is referred to as a “plant defense activator” because it produces an induced systemic resistance response and thus activates a plant’s natural defense system.

IV. Humic substances

Humic substances (e.g., humic and fulvic acids) are natural decomposition constituents of soil organic matter, typically derived from leonardite (a natural form of humates), associated with “brown coal” deposits. Benefits of these compounds increased soil nutrient and water holding capacity (e.g., increased cation exchange capacity), prevention and reduction in leaching of soil nutrients, chelators of organic molecules and minerals facilitating increased plant root absorption, enhanced soil enzyme and metabolic activity.

Table 1. Proposed classification of biostimulants for turfgrass science and industry.

PLANT

1

Category

I Phytohormones

II Biopolymers, protein hydrolysates, and other N-containing compounds

Examples of active or functional ingredients

Abscisic acid

Auxins

Cytokinins

Ethylene

Gibberellic acid

Others

Amino acids (e.g., proline, etc.)

Antioxidants

Betaines

Chitin

Enzymes

Fatty acids

Non-protein amino acids

Peptides

Polyamines

Polysaccharides

Vitamins

III Other botanical or synthetic bioactive compounds

Examples of biostimulant products 2

algae, indoleacetic acid, benzyl-adenine, gibberellins, kelp, seaplant, seaweed extracts, and more

Others amino acids, chitosan, glycine betaine, and more

Elicitor compounds, Induced systemic resistance compounds, Plant defense activator compounds,

Others acibenzolar-S-methyl, jasmonic acid, salicylic acid, and more

1 Category based on chemical and/or physical composition.

2 Broad or general name of a biostimulant product listed; no product trade name provided. Should an additional column list the specific biostimulant function of those biostimulant products, and/or should the manufacturer include that information on their product label?

SOIL / RHIZOSPHERE

Category 1 Examples of active or functional ingredients

IV Humic substances Fulvic acid

Examples of biostimulant products 2

Humic acid leondardite, and more

V Organics Biochar

Bio-extracts

Bio-fertilizers

Composts/compost extracts

Soil amendments/supplements

Others

VI Inorganics / minerals

VII Biologicals / microbials

biochar, composts, compost teas, kelp, seaplant, seaweed extracts, vermi/worm extracts, and more

Al, Co, Na, Mo, Se, Si, etc.

Phosphites

Others phosphite salts, and more

Beneficial fungiArbuscular mycorrhizal fungi

Trichoderma spp.

Others

Beneficial bacteriaBacillus spp. and other species

Plant growth promoting

rhizobacteria

Others

Other beneficial organisms

Many

VIII Soil surfactants 3 --?-- --?--

IX Other naturally derived or synthetic bioactive compounds

Elicitor compounds

Induced systemic resistance compounds

Plant defense activator compounds

Others --?--

1 Category based on chemical and/or physical composition.

2 Broad or general name of a biostimulant product listed; no product trade name provided. Should an additional column list the specific biostimulant function of those biostimulant products, and/or should the manufacturer include that information on their product label?

3 Proposed location of soil surfactants as a category if some of those soil surfactants are to be considered or included as biostimulants.

V. Organics

Traditionally, organic amendments such as peat moss, manures, biosolids, composts, and other materials have been added to sand-based turfgrass rootzones to increase water and plant nutrient retention and availability. Ideally, organic materials and substances applied to turfgrass soils should be sufficiently decayed and biologically stable and decompose very slowly so their benefits or positive impact can be expressed over a long time. Recently, biochar has gained interest due to a high carbon content, porosity, and stability (e.g., extremely resistance to microbial degradation). Vermicompost extract also is popular for improving the biological and physical health of the turfgrass rootzone.

VI. Inorganics / minerals

Many inorganic/mineral compounds and products can be placed into this category. Phosphite (PO33-) of has become the most common inorganic compound incorporated into many turfgrass management programs, particularly with disease management and suppression.

VII. Biologicals / microbials

Numerous biological/microbial organisms can be placed into this category. Arbuscular mycorrhizal fungi form a mutually symbiotic relationship with plant roots, in which roots provide carbohydrates for the fungi and the fungi aid in access and

transfer of nutrients and water to the plant roots, and also aid in water balance, and abiotic and biotic stress tolerance or protection. Bacillus spp. is the most common example of a bacterial organism utilized for biological control of plant pathogens, and this is achieved via direct suppression by the release of antipathogen compounds, or via indirect mechanism such as outcompeting the pathogen for space or food, or for activating or inducing plant defense systems. Current research is exploring plant growth promoting rhizobacteria and their ability to confer beneficial effects on plant growth and development by increased nutrient uptake (e.g., nitrogen and phosphorus), synthesizing plant growth promoting compounds, activating abiotic and biotic stress tolerance mechanisms, and possibly more.

VIII. Soil surfactants

Agriculture, horticulture, and turfgrass industry practitioners commonly refer to soil surfactant products as “wetting agents.” Should all or some specific soil surfactants be listed as a biostimulant? Can soil surfactants “behave as biostimulants,” or “facilitate a biostimulant effect” when applied to turfgrass rootzones? Surfactants are primarily and traditionally used for water conservation, improving irrigation use efficiency, and ameliorating soil water repellency. The utilization of soil surfactants is considered the number one water conservation strategy among golf course superintendents in the USA. Current research indicates certain diverse rootzone processes can be “engineered” by surfactants to optimize rhizosphere and soil biophysical, microbiological, and chemical properties (Figure 1).

Figure 1. An example of a beneficial application program of Excalibur soil surfactant (AquaAid Solutions; Rocky Mount, NC) on a creeping bentgrass putting green subjected to drought stress. The volumetric water content status of the rootzone was improved to optimize the function of the rhizosphere. A: Illustration depicting good or optimum root-to-soil contact in Excaliburtreated plot. B: Illustration depicting poor root-to-soil contact in untreated plot. C: Healthy and dense turfgrass visible within the plot, indicating good root-to-soil contact and access to water and nutrients. D: Drought stress visible within the plot, indicating roots with compromised physiological function.

Images in A and B from: Weil R.R. and Brady, N.C. 2017. The nature and properties of soils. 15th ed. Pearson Education, New York City, NY. Images in C and D from: Duddek, P., Carminati, A., Koebernick, N., Ohmann, L., Lovric, G., Delzon, S., Rodriguez‐Dominguez, C., King, A., and Ahmed, M.A. 2022. The impact of drought-induced root and root hair shrinkage on root–soil contact. Plant Physiology 189:1232-1236.

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IX. Other naturally derived or synthetic bioactive compounds

This category is a “place-holder” for soil-directed compounds not yet described or fully understood, or for compounds that do not fit the description of the other categories. Before considering a biostimulant product or program, a prudent and responsible turfgrass manager should ask “What is in it?” and “What does it do?” (Table 2).

Table 2. Should I use this product on my turf? Eight questions to ask when evaluating a biostimulant, soil amendment, or other turf product to help you make sound, fact-guided agronomic decisions 1

1. Is this product needed in my situation?

2. Are independent test results available?

3. What is the magnitude of response?

4. Does this product provide consistent results?

5. What is the duration of response?

6. Are there better alternatives?

7. Do benefits justify the costs?

8. Should I try this product on a trial area?

1 Source: Carrow, R.N. 1993. Eight questions to ask: Evaluating soil and turf conditioners. Golf Course Management 61(10):56, 58, 60, 64, 70.

The purpose of asking questions about biostimulants is to help guide the turfgrass manager towards making the best fact-based agronomic decision. More questions are helpful to further explore a biostimulant’s intended use (e.g., abiotic or biotic stress, plant nutrient efficiency, etc.) and ability to produce or facilitate the desired turfgrass response (Table 3).

A biostimulant or combinations of biostimulants may provide turfgrass management options to maintain or improve turfgrass quality and function during abiotic and/or biotic stress conditions. Moderating and mitigating these stresses are an important strategy to establishing and maintaining healthy, resilient, and sustainable turfgrass. Therefore, should a biostimulant product or program become a valuable component of turfgrass management? The answer to that question may depend on what exactly the turfgrass practitioner wants to accomplish (e.g., better rooting, better tolerance of heat or drought stress, improved recovery from heat or drought stress, traffic tolerance, turf recovery, disease prevention, turf recovery from disease, better color or visual quality, better playability, etc.).

Regardless of the biostimulant product or strategy it is important to note that biostimulants are not a substitute for essential mineral nutrients and a sound agronomic-based turfgrass management program. If the goal is to include or incorporate biostimulants as part of an overall plant and soil health program, then the research in turfgrass ecosystems has demonstrated that they must be applied in advance of those abiotic and biotic stresses to optimize their benefits. There are many exciting innovations on the nearby horizon and evidencebased efforts will lead the way toward a better understanding of how biostimulants will help maintain and improve plant and soil health. Today, much more scientific research is focused on the development, evaluation, use, function, and benefits of biostimulants for sustainable agronomic practices in intensively managed amenity turfgrass ecosystems.

Source: Fidanza, M., C. Bigelow, S. Kostka, E. Ervin, R. Gaussoin, F. Rossi, J. Cisar, F.D. Dinelli, J. Pope, and J. Steffel. 2023. Advances in biostimulants in turfgrass. In Fidanza, M. (Ed.), Achieving Sustainable Turfgrass Management. Burleigh Dodds Science Publishing; Cambridge, UK. p. 469-501.

Table 3. What are key questions golf course superintendents, greenkeepers, course care managers, sports field managers, and lawn and landscape professionals should ask when considering a biostimulant product?1

• What’s in it? What is the product’s composition or active ingredient(s) or component(s)?

• What is its function? How does the product claim to benefit turfgrass?

• Will the product function in all climates, soil types, turfgrass species, and turfgrass cultural practices and management programs?

• Does the product function best to help with abiotic (e.g., drought, heat, salt) or biotic (e.g., insects, pathogens, traffic) stresses?

• Where’s the data? What does the research-based data show that the product does when the product is applied to turfgrass? Were the effects both qualitative and quantitative in replicated field and/or controlled greenhouse research?

• Does the manufacturer have clear research-based data showing that all or most of the product’s active ingredients are essential to its function? Does the data show how individual ingredients, when tested against the formulated product, no longer provide the functional benefit?

1Adapted from: Fidanza, M., Kostka, S., Ervin, E., and Bigelow, C. 2019. The European Union’s view on biostimulants: What may be coming our way. Golf Course Management 87(9):58-62. Achieving Sustainable Turfgrass Management (https://tinyurl.com/2676ukn9) •