Mississippi Turfgrass - Spring 2024

Page 1

Control of Yellow and Knotroot Foxtail in Southern Turfgrass

Association
SPRING 2024
The Mississippi Turfgrass
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Considerations with Biostimulants For Turfgrass Management
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Turfgrass is the Mississippi Turfgrass Association magazine. Subscriptions are complimentary to MTA members. The statements and opinions expressed herein are those of the individual authors and do not necessarily represent the views of the association, its staff, its board of directors, Mississippi Turfgrass, or its editors. Likewise, the appearance of advertisers, or their identification as MTA members, does not constitute an endorsement of the products or services featured in any issue of Mississippi Turfgrass. Copyright © 2024 by the Mississippi Turfgrass Association. Mississippi Turfgrass is published quarterly. Subscriptions are complimentary to members of MTA. Presorted standard postage is paid at Jefferson City, MO. Printed in the U.S.A. Reprints and Submissions: MTA allows reprinting of material published here. Permission requests should be directed to MTA. We are not responsible for unsolicited freelance manuscripts and photographs. Contact the managing editor for contribution information. Advertising: For display and classified advertising rates and insertions, please contact Leading Edge Communications, LLC, 206 Bridge Street, Suite 200, Franklin, TN 37064, (615) 790-3718, Fax (615) 794-4524. CONTENTS • The Mississippi Turfgrass Association Magazine DEPARTMENTS
From the MTA President 6 Calendar of Events 9 Index of Advertisers COVER STORY
Control of Yellow and Knotroot Foxtail in Southern Turfgrass RECENT EVENTS
GCSAA Hospitality Night 12 2024 Turf Workshop FEATURES
Considerations with Biostimulants For Turfgrass Management UPCOMING EVENT
Yard Dawg Classic Golf Tournament SPRING 2024 4 • MISSISSIPPI TURFGRASS • SPRING 2024 10 12 18
Mississippi
6
14
10
18
8
The Right Grass for Your Home Turf! Doug Estes 901-268-8803 PRESIDENT Bobby Winstead 901-867-8116 Whit Davis 615-405-3705 Chance Meredith 901-430-5620 While serving the entire Mid-South for the past 45 years, our goal continues to provide the highest quality, innovative turfgrass on the market today while providing the best customer service. winsteadturffarms.com Middle / East TN • Winstead Turf Farms, Inc. • 296 Bill and John Ln. • Hurricane Mills, TN 37078 • 615-405-3705 winstead-turf-farms-inc winsteadturffarm @winsteadturf winsteadturf COMING SOON West TN • Winstead Turf Farms, Inc. • 22860 Highway 196 • Arlington, TN 38002 • 901-867-8116 GOLF • ATHLETIC FIELDS • LANDSCAPES • HOME LAWN

Growing Relationships

Spring is finally here, and no one is more excited than I am! Don’t get me wrong, I love to see the progress and change that winter projects bring, but there’s only so much cold weather and rain I can stand. Hopefully we will all see more favorable conditions for this year’s growing season.

We hope that each of you had plenty of time to get caught up with your projects and spend some down time growing relationships with family, friends, and employees. This is just as important as growing grass, and MTA strives to bring you plenty of opportunities to grow your industry relationships.

The GCSAA Conference is typically a long haul for most of us, but I hear we had a great turnout at our Hospitality Night there in January. We’re back at MSU Golf Course for this year’s Yard Dawg Classic on June 11th and we encourage you all to be there! We have a tournament committee set up to ensure everything runs smoothly again this year.

Thank you all for your support of the MTA. I hope your year is off to a great start!

2024

June 11, 2024 Yard

September

October 14 – 17, 2024 Deep

February 5, 2025 MSU

Mississippi Turfgrass Association Box 9555

MS State, MS 39762

Office: (662) 325-0517

Fax: (662) 325-2705

www.msturfassociation.org

Published by:

Leading Edge Communications, LLC

206 Bridge Street

Franklin, TN 37064

Office: (615) 790-3718

Fax: (615) 794-4524

info@leadingedgecommunications.com

MISSISSIPPI TURFGRASS EDITOR

Dr. Jay McCurdy

MTA OFFICERS

PRESIDENT

Levi Jumper

Tupelo National Golf Club (662) 213-6804

VICE-PRESIDENT / PRESIDENT ELECT

Scott Hampton

Laurel Country Club (601) 467-2718

SECRETARY-TREASURER

Dr. Barry Stewart

Mississippi State University

Office: (662) 325-2725

IMMEDIATE PAST PRESIDENT

Will Arnett

EMCC – Lion Hills (662) 418-1939

ADMINISTRATIVE SECRETARY

Linda Wells

Mississippi State University Box 9555

MS State. MS 39762

Office: (662) 325-0517

Cell: (662) 769-7558

lmw218@pss.msstate.edu

DIRECTORS

Chance Meredith / Sod Winstead Turf Farms (901) 430-5620

Zak Holloway / Golf Old Waverly Golf Club (662) 386-8042

Josh Smith / Grounds / Lawn Maintenance (601) 441-8029

Evan Berry / Central Mississippi Braves (228) 304-1234

Toby Thornton / South SiteOne Landscape Supply (601) 507-4254

Seth King / Industry

Ben Nelson Golf and Outdoor (601) 672-4796

EX-OFFICIO

Dr. Jay McCurdy / Faculty Advisor

Mississippi State University (662) 325-2331

FROM THE MTA PRESIDENT
6 • MISSISSIPPI TURFGRASS • SPRING 2024
Classic
Golf Course
Dawg
MSU
Workshop
Show
January (Date TBD) MTA Turf
Road
Expo
South Turf
Biloxi
Field Day
19, 2024 MSU Turfgrass
Starkville
Alumni/Associations
Night
Diego, CA
Hospitality
San
2024 CALENDAR OF EVENTS 2025 CALENDAR OF EVENTS
Thank You. SODSOLUTIONS.COM CAGLE SOD FARM • OASIS SOD FARM BATTLE SOD FARM • YAZOO SOD
UPCOMING EVENT 8 • MISSISSIPPI TURFGRASS • SPRING 2024
THE MISSISSIPPI TURFGRASS ASSOCIATION MAGAZINE • 9 Office: 205-333-1776 www.surlineturf.com • email: surline1@gmail.com SPECIALIZING IN: Athletic Field Construction and Renovation Golf Course Construction and Renovation Laser Grading • Super Topdressing No-Till Planting • Sodding • Sprigging On-Site Custom Built Turf Covers Fertilizer • Seed • Turf Colorant Sod Staples • Bunker Nails • Bunker Liners Sod • Sprigs • Sand • Mixes Infield Mix • Infield Conditioners Warning Track Stone • Mound Clay Riebeling Farms, Inc. 251-943-6012 CitraBlue St Augustine • Palmetto St Augustine Empire Zoysia • Centipede Sod • Delivery Available 20732 Hadley Rd. • Foley, AL. 36535 INDEX OF ADVERTISERS Chattahoochee Turf Products 11 www.chattahoocheeturfproducts.com DryJect 21 Greene County Fertilizer Co. 13 www.greenecountyfert.com Harrell’s LLC Back Cover www.harrells.com Jackson Sand....................................................... 11 www.jacksonsand.com Jerry Pate Turf & Irrigation Inside Back Cover www.jerrypate.com NewLife Turf, Inc. 13 www.newlifeturf.com Progressive Turf Equipment Inc. 17 www.progressiveturfequip.com Regal Chemical Company Inside Front Cover www.regalchem.com Riebeling Farms, Inc. 9 riebelingfarmsinc@gmail.com Site One 15 www.siteone.com Smith Seed Services 13 www.smithseed.com Sod Solutions 7 www.sodsolutions.com Sur-Line Turf, Inc. 9 www.surlineturf.com The Turf Zone 3 www.theturfzone.com Weed Man 11 www.weedmanfranchise.com Winstead Turf ........................................................ 5 www.winsteadturffarms.com To discuss advertising opportunities, contact Leading Edge Communications: 888-707-7141 ( Toll Free ) sales@leadingedgecommunications.com www.LeadingEdgeCommunications.com

MSU Alumni & Associations Hospitality Night

January 31st, Phoenix, AZ

Gathered together in Phoenix for the GCSAA Conference & GIS, we hosted a hospitality night for our members from Mississippi, Alabama, Louisiana and the Gulf Coast of Florida. The event is always well attended with over 100 gathering at Hanny’s restaurant. It is always good to catch up with friends and colleagues we haven’t seen since last year and get to see some we have not seen in years! We had a good time!! •

RECENT EVENTS
10 • MISSISSIPPI TURFGRASS • SPRING 2024
THANKS TO OUR HOSPITALITY NIGHT SPONSORS !
Upper L to R: Dr. Barry Stewart, Amy Wilber, Jason Eberhard, Bottom L to R: Dr. Marta Pudzianowsha, Linda Wells, Amanda Miles. Photo courtesy of Amanda Miles.
Agronomic Solutions for Turfgrass Management www.chattahoocheeturfproducts.com Fax: 229-853-2767 Email: ompo@aol.com Office: 229-853-9469 Mobile: 229-406-0321 205 Tommy Warren Drive Cobb, GA 31735 ROGER MYERS PRESIDENT One of the best franchises to buy in America. - Forbes Magazine NO. 2 RANKED The Best Franchises to Buy Lowest Level Investment < $150K Opportunity by Forbes NO. 1 RANKED Franchise in Lawn Care by Entrepreneur Magazine year after year NO. 1 RANKED In Franchise Business Review’s Top Service Franchises FOR FRANCHISE INFORMATION: weedmanfranchise.com or call (888) 321-9333 S C A N F O R FRANCHISE INFO

Highlights from the 2024 Turf Workshop

Lion Hills Center in Columbus, Mississippi again hosted the annual MTA January Turfgrass Workshop. It was well attended—79! Led by an excellent group of educators, attendees were updated on soil fertility, insect pests on urban trees, current management assessment on the ERI diseases Take-All and Spring Dead Spot, trends in warm season turf breeding and a turfgrass weed science update. Attendees were also brought up to date on the rules and regulations of the Mississippi Bureau of Plant Industry. •

The Mississippi Turfgrass Association appreciates the support of these sponsors:

Agra Turf, Inc.

Corteva Envu

Harrell’s, Inc.

Sur-Line Turf

Lunch sponsor: pbi/GORDON

Thanks to Lion Hills Center and East Mississippi Community College for their support.

RECENT EVENTS • Continued
12 • MISSISSIPPI TURFGRASS • SPRING 2024
Dr. Marta Pudzianowska discusses the turf breeding program at MSU Dr. Barry Stewart discusses soil fertility Attendees Dr. Jay McCurdy
Growth Happens Here. High performance liquid fertilizers, soil amendments, and every control product you need is right here under one roof. GROW YOUR BUSINESS. WE’LL GROW YOUR TURF. Healthy turf starts with Greene County Fert. GreeneCountyFert.com Pro Tech Suppport • Buy/Ship Direct Experience Ma�ers Our knowledge of the industry and collabora�on of premier turf experts gives us an edge. We are commi�ed to providing our customers with the total experience from selec�on to the final product. That’s a promise! Our Turf Our Services Installa�on . Sprig Plan�ng . Greens Renova�on 2024 Willow Swamp Road . Norway, SC . 803.263.4231 www.newlifeturf.com . info@newlifeturf.com

Control of Yellow and Knotroot Foxtail in Southern Turfgrass

| Current address of first author: University of Florida

Inthe southeastern region of the United States, Setaria pumila and Setaria parviflora, respectively known as yellow and knotroot foxtail, are two common species infesting managed and unmanaged turfgrass, pastures, roadsides, and some cropping systems (Bryson and DeFelice, 2009; Hitchcock, 1971). Yellow and knotroot foxtail originated from Asia and North America, respectively (Dekker, 2003; Rominger, 1962a). Nevertheless, they are very similar in appearance and are frequently mistaken for each other, leading to confusion in herbicide selection (Darmency and Dekker, 2011).

The primary differences between yellow and knotroot foxtail are found in the seedhead with yellow foxtail seedheads bigger and denser with more hairs (Darmency and Dekker, 2011). Other studies found that knotroot foxtail can be differentiated from yellow by the presence of rhizomes (Wang et al., 1995). However, since these characteristics appear late during development or sometimes are not apparent at all, it is very difficult to tell the two species apart in the field (Wang et al., 1995).

Yellow and knotroot foxtail are annual and perennial weeds, respectively, with few options for effective chemical control in warm-season turfgrass. Pinoxaden is labeled in the United States for use on bermudagrass controls of yellow foxtail post emergence (Peppers et al., 2020), but pinoxaden is not labeled to control knotroot foxtail (Peppers et al., 2020). Chlorsulfuron gave season-long control of yellow foxtail when applied at the early growth stage in Kentucky bluegrass, but it is not labeled in turfgrass (Maloy, 1985). Imazethapyr controls yellow foxtail effectively as a preemergence with no detrimental effects on grass establishment (Fry et al., 1997).

Little research has been done to gain an understanding of the chemical control of knotroot foxtail. In pastures, hexazinone alone or applied with metsulfuron + dicamba + 2,4-D, controlled knotroot foxtail by more than 70% two weeks after application, as did chlorsulfuron or nicosulfuron (Coats et al., 1999). Nicosulfuron + metsulfuron controls knotroot foxtail 70% in bermudagrass forage at the actively growing stage (Rusell, 2021).

Other herbicides could potentially control yellow and knotroot foxtail but are not currently labeled. For instance, thiencarbazone + dicamba + iodosulfuron is labeled for controlling yellow foxtail and giant foxtail but not knotroot foxtail.

The objectives of this research were to (1) evaluate the response of yellow foxtail and knotroot foxtail to several turfgrass herbicides and (2) evaluate the rate response of yellow and knotroot foxtail to increasing rates of pinoxaden and sethoxydim and estimate the application rate at which 50% (I50) of both species was injured.

Material and Methods

Research was conducted in 2021 and 2022 in greenhouse populations to evaluate yellow and knotroot foxtail response to different turfgrass herbicides. Two experiments were conducted at the Auburn University Weed Science greenhouse in Auburn, AL in 32/28 C (+/-1 C Day/night) conditions with an average relative humidity of 70%. Seeds of both species were harvested from a local population in Montgomery, Alabama. Seeds were cleaned and stored at 4oC prior to the experiments. Seeds were planted in flats of potting medium and were then transplanted individually at three leaves stage into 230 cm3 pots, filled with sandy soil. Treatments were applied two weeks after transplantation. After treatment, pots were not watered for approximately 24 hours to allow for adequate leaf absorption. See Figure 1 for the herbicide treatments.

The treatments were evaluated for percent weed control at 7, 21 and 28 days after application (DAA) and above ground biomass of the foxtail plants were evaluated at 28 DAA.

Herbicide

Manuscript (Pinoxaden)

Manuscript (Pinoxaden)

Segment (Sethoxydim)

Rate applied

0.673 Kg/ha (9.6 fl oz/a)

1.345 Kg/ha (19.2 fl oz/a)

3.15 L/ha ( 2.25 pt/a)

Segment (Sethoxydim) 5.25 L/ha (3.75 pt/a)

Celsius (Thiencarbazone+Dicamba+lodosulfuron) 0.344 kg/ha (4.9 oz wt/a)

Sencor (Metribuzin)

0.750 Kg/ha (0.67 lb /a)

Steadfast (Nicosulfuron +Rimsulfuron) 0.052 Kg/ha (0.75 oz wt/a)

Dismiss FMC (Sulfentrazone) 0.841 Kg/ha (12 fl oz/a)

Dismiss South (Sulfentrazone +Imazethapyr) 1.016 kg/ha (14.5 fl oz/a)

Scepter (Imazaquin)

untreated

0.799 Kg/ha (11.4 oz wt/a)

COVER STORY
14 • MISSISSIPPI TURFGRASS • SPRING 2024
Figure 1. Herbicide treatments applied to yellow and knotroot foxtail in this study

Results and Discussion

In greenhouse evaluation, yellow and knotroot foxtail responded differently to the selected herbicides. All the herbicides were effective on yellow foxtail with more than 85 % at 28 days after application (DAA) (Figure 2). Aboveground biomass data followed the same pattern. All the herbicides reduced yellow foxtail above-ground biomass by more than 95% compared to the nontreated at 28 DAA.

Knotroot foxtail was more difficult to control in general than yellow foxtail. Sulfentrazone controlled knotroot foxtail > 90 %, which was the best treatment statistically. Similarly, metribuzin controlled knotroot foxtail 81%, imazaquin 71%, sethoxydim (high rate) 76%, and thiencarbazone + dicamba + iodosulfuron 68% control (Figure 2). All the other treatments controlled knotroot foxtail by less than 65%. Relative plant fresh-weight data agreed with visually estimated control data. Sulfentrazone, metribuzin, sethoxydim (high rate), thi encarbazone+dicamba+iodosulfuron and imazaquin reduced the above ground biomass by more than 90% and nicosulfuron+rimsulfuron reduced knotroot foxtail biomass by 89%. However, pinoxaden (low and high rates) were less effective on knotroot foxtail with less than 30% biomass reduction.

Bottom Line

This study found that yellow foxtail responded differently to herbicides than knotroot foxtail, and knotroot foxtail was more difficult to control. Based on the greenhouse studies, sulfentrazone, sethoxydim (high rate) thiencarbazone + dicamba + iodosulfuron, and metribuzin can be considered for controlling yellow and knotroot foxtail at label rates. Knotroot foxtail response was more variable and pinoxaden should not be considered for controlling knotroot foxtail even at the maximum recommended label rate. Sethoxydim provided effective control of yellow foxtail and reduced knotroot foxtail biomass by more than 60% at the labeled rate. Responses observed in this study suggest that differentiation between yellow and knotroot foxtail is essential for predictable results with herbicides. •

Literature Cited

Darmency

COVER STORY • Continued 16 • MISSISSIPPI TURFGRASS • SPRING 2024
Bryson CT, DeFelice MS (2009) Weeds of the south Athens, GA: University of Georgia Press. Pp. 495 Coats GE, Taylor JM, Kelly ST, Helms RB, Scott TD (1999) Highway vegetation management Mississippi: Miss. Agric. and Forest. 122 p H, Dekker J (2011) Setaria. Pages 275-291 in Kole C, ed. Wild Crop Relatives : Genomic and Breeding Resources. Clemson: Springer Figure 2. Control of yellow foxtail with various herbicide treatments at 7, 21 and 28 days after application (DAA) Figure 3. Control of knotroot foxtail with various herbicide treatments at 7, 21 and 28 days after application (DAA)

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Dekker J (2003) The foxtail (Setaria) species-group. Weed Science 51:641-656

Dyer LM, Henry GM, McCullough PE, Belcher J, Basinger NT (2022) Knotroot Foxtail [Setaria parviflora (Poir.) Kerguélen]:“A sly fox”. Weed Technology:1-22

Fry JD, Gaussoin RE, Beran DD, Masters RA (1997) Buffalograss Establishment with Preemergence Herbicides. Hortscience 34 Hitchcock AS (1971) Manual of the grasses of the United States. New york: Dover

Kotu V, Deshpande B (2018) Data science: concepts and practice: Morgan Kaufmann

Maloy BM (1985) Selective control of perennial grasses in Kentucky 21 blue-grass (Poa pratensis L.) turf with chlorsulfuron. Master of science Iowa Iowa State University

Ogle DH, Doll JC, Wheeler P, Dinno A (2022) FSA: Fisheries Stock Analysis

Peppers JM, Gonçalves CG, McElroy JS (2020) Rate response of select grass weeds to pinoxaden. Weed Technology 34:818-823

Ritz C, Baty F, Streibig J, Streibig C, Gerhar D (2015) DoseResponse Analysis Using R. PLOS ONE 10

Rominger JM (1962) Taxonomy of Setaria (Gramineae) in North America in Press TUoI, ed. Urbana

Rusell D (2021) Widespread Foxtail Distribution Leads to Tough Management Decisions. Forages

Wang RL, Wendel JF, Dekker JH (1995) Weedy adaptation in Setaria spp II Genetic diversity and population genetic. American Journal of Botany 82:1031-1039

THE MISSISSIPPI TURFGRASS ASSOCIATION MAGAZINE • 17
available with bolt-on galvanized deck shells
Manuscript Manuscript Control Steadfast Dismiss Celsius Sencor Dismiss South Segment Segment Scepter
This article was originally published in Alabama Turf Times, Spring 2024 and is reprinted with permission.
Figure 4. Yellow (top) and knotroot (bottom) foxtail plants at 28 days after herbicide application

Considerations with Biostimulants for Turfgrass Management

The 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 defense-activating 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

FEATURE
18 • MISSISSIPPI TURFGRASS • SPRING 2024

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.

PLANT

Category 1 Examples of active or functional ingredients Examples of biostimulant products 2

I Phytohormones Abscisic acid

Auxins

Cytokinins

Ethylene

Gibberellic acid

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

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

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

Antioxidants

Betaines

Chitin

Enzymes

Fatty acids

Non-protein amino acids

Peptides

Polyamines

Polysaccharides

Vitamins

Others amino acids, chitosan, glycine betaine, and more

III Other botanical or synthetic bioactive compounds 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 Examples of biostimulant products 2

IV Humic substances Fulvic acid Humic acid leondardite, and more

V Organics Biochar

Bio-extracts

Bio-fertilizers

Composts/compost extracts

Soil amendments/supplements

Others

VI Inorganics /minerals Al, Co, Na, Mo, Se, Si, etc.

Phosphites

VII Biologicals/ microbials

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

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.

THE MISSISSIPPI TURFGRASS ASSOCIATION MAGAZINE • 19
Table 1. Proposed classification of biostimulants for turfgrass science and industry.

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).

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 Excalibur-treated 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.

FEATURE • Continued
20 • MISSISSIPPI TURFGRASS • SPRING 2024
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.
Root Hairs Turgid Root Major Cortex Drying Root Other Soil Surfactant Excalibur Non-Treated Non-Treated with-inplot ‘check strip’
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The

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?

1Source: 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 evidence-based 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. •

• 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?

Achieving Sustainable Turfgrass Management

• 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.

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22 • MISSISSIPPI TURFGRASS • SPRING 2024 FEATURE • Continued
(https://tinyurl.com/2676ukn9)
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
This article was originally published in Pennsylvania Turfgrass Magazine, Spring 2024 and is reprinted with permission.
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