Turfgrass Epistemology

S3 E66 Dr. John Inguagiato. Can Phosphite Reduce Algae?

In this episode of Turfgrass Epistemology, I sit down with Dr. John Inguagiato to discuss his peer-reviewed research on phosphite use for suppressing cyanobacteria (blue-green algae) on putting greens. Together, we break down the science behind phosphite chemistry, application rates, turf safety, and what the data actually say—beyond marketing claims.
Dr. Inguagiato’s 2017 Crop Science paper, “Effect of Phosphite Rate and Source on Cyanobacteria Colonization of Putting Green Turf,” is one of the most frequently cited studies on this topic. In this conversation, we explore how phosphite differs from phosphate, why cyanobacteria respond differently to these compounds, and how phosphite applications can reduce algal crusting without relying solely on traditional fungicides 
This discussion covers:How phosphite suppresses cyanobacteria colonization on creeping bentgrass putting greensDifferences between phosphite vs. phosphate in turf systemsOptimal phosphite application rates that balance efficacy and phytotoxicity riskWhy product source and formulation matter less than active ingredient ratePractical implications for algae management programs on golf greensHow this research fits into modern integrated turfgrass management
If you manage putting greens, work in turfgrass research, or want an evidence-based explanation of phosphite products that cuts through anecdote and advertising, this episode provides critical context straight from the study’s lead author.
📄 Research discussed:Inguagiato, J.C., Kaminski, J.E., & Lulis, T.T. (2017). Effect of Phosphite Rate and Source on Cyanobacteria Colonization of Putting Green Turf. Crop Science 57: S-274–S-284.
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#TurfgrassScience #GolfCourseManagement #Phosphite #Cyanobacteria #PuttingGreens #TurfgrassResearch #SoilScience #EvidenceBasedTurf #TurfgrassEpistemology
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Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
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Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf
Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

S3 E65 Tinfoil Turfgrass: Soil Testing Goes Extreme!

In this video I take a close, critical look at "Data-Drive Lawn Care" (https://www.youtube.com/watch?v=pjRXNcIi3Hk) and share my honest thoughts on what works — and what doesn’t. I break down the arguments, highlight where I think the logic falls short, and offer my own perspective on the topic.
🔎 What I cover:
Key claims made by the original creator
Moments where I agree — and moments where I respectfully disagreeGlaring omissions and what I believe should have been addressedMy own take: what’s convincing, what needs more nuance
💡 Why this matters:Discussions like this are important — not just to critique others, but to encourage deeper thinking and accountability. If you’ve seen the original video: I invite you to watch this, think along with me, and decide for yourself what holds up.
👇 Join the conversation:Do you agree or disagree with my take?Did I miss anything?What would you add?Let me know your thoughts in the comments — I read them all 🙂
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Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
Spotify Podcasthttps://open.spotify.com/show/1cTpdrChToeEFAOX9wkXFI
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Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf
Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

S3 E64 Grey Leaf Spot, Mowing Height, and Nitrogen

In this video, I review and break down one of the most referenced articles in cool-season turfgrass pathology: “Severity of Gray Leaf Spot in Perennial Ryegrass as Influenced by Mowing Height and Nitrogen Level” by Williams, Burrus, and Vincelli (2001).
This study investigated how two major management practices—mowing height and nitrogen rate—affect the intensity of gray leaf spot (Pyricularia grisea) epidemics in perennial ryegrass managed under golf-course conditions.
I walk through the methods, results, and implications of the research, and I discuss how the findings align—or don’t align—with common industry assumptions twenty years later.
🔬 Topics I cover in the review:
The study design and why the researchers chose fairway- and rough-height mowingHow N rates (0, 36.6, and 73.2 kg N ha⁻¹ per month) influenced GLS severityWhy mowing height had less effect on disease than expectedEnvironmental conditions that shaped the epidemicWhat turf managers can actually take away from this paperHow these results compare to modern GLS observations in perennial ryegrass
💡 Why this article matters today:Gray leaf spot remains one of the most destructive diseases of perennial ryegrass on golf courses. Understanding how cultural practices influence disease severity is still essential for developing integrated, evidence-based management programs. This paper is a cornerstone in that conversation—and it still sparks debate.
👇 Join the discussion:
Do you agree with how the authors interpreted their data?Have you observed different mowing-height effects in your region?Should N programs be modified during GLS-prone months?
Share your thoughts in the comments. Critical evaluation of research—new and old—is how we advance turfgrass science and avoid assumptions that fail in the field.
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Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
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Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf

S3 E63 Tinfoil Turfgrass: How to Evaluate Claims When The Salesman Knows More Than You.

In this video, I provide an in-depth, evidence-based critique of the nitrogen-efficiency product RDX-N and the claims made in the promotional video circulating online. If you’ve ever wondered whether biostimulants, nitrogen enhancers, or “metabolic activators” actually work in real-world turfgrass or crop management, this breakdown is for you. I review the product’s marketing claims, examine the data presented in the official RDX-N brochure, and explain what the science really says about nitrogen uptake, nitrogen metabolism, and plant physiology.
But this video is more than a review of one product—it's a lesson in how to evaluate agronomic claims using critical thinking and epistemology.When you understand how knowledge is justified, you’re better equipped to:• Identify misleading or unproven claims• Recognize when data is incomplete, selective, or irrelevant• Avoid being persuaded by marketing language• Make informed decisions based on reliable evidence
In turfgrass, agriculture, and lawn care, new products appear constantly—each claiming to increase yields, improve nitrogen efficiency, reduce inputs, or boost plant health. Without strong critical thinking skills, it’s easy to be misled. Epistemology—the study of how we know what we know—helps protect you when you’re confronted with products, technologies, or scientific claims you’ve never heard of.
By the end of this video, you’ll understand:• What RDX-N claims to do• Whether those claims are supported by high-quality evidence• How to assess scientific credibility in turfgrass and crop management• How to apply critical thinking when evaluating any agronomic product
If you’re a turfgrass manager, agronomist, sports field manager, lawn care professional, or scientifically curious homeowner, this channel will help you make smarter, evidence-driven decisions.
Subscribe to Turfgrass Epistemology for more videos on turfgrass science, nitrogen management, soil fertility, agronomy, and the critical thinking skills needed to navigate misinformation in the industry.
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Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
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Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf
Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

S3 E62 Dr. Lee Miller - Turf Fungicide Resistance?

In this episode of Turfgrass Epistemology, I sit down with Dr. Lee Miller of Purdue University, one of the leading experts in turfgrass pathology, to break down everything you need to know about turfgrass disease resistance, fungicide rotations, and accurate turf disease identification. Whether you manage golf course greens, sports fields, or home lawns, this conversation gives you the practical, science-based guidance needed to protect your turf from common and emerging diseases.
We explore what disease resistance in turfgrass truly means, why resistance develops, and how environmental conditions and management practices influence disease pressure. Dr. Miller explains how to design effective fungicide rotation programs, how to avoid resistance through proper FRAC group management, and how to choose the right mode of action at the right time of year.
If you’re looking for evidence-based turfgrass management, best practices for fungicide use, or expert insights into turf disease diagnostics, this video delivers the tools you need.
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Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
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Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf
Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

S3 E61 Fungicides and Species Resistances Affects Dollar Spot

In this video, I analyze the 2025 Zhang et al. study on how fungicide scheduling and bentgrass cultivar resistance interact to influence dollar spot control. This research provides some of the strongest evidence to date that curative, damage-threshold-based fungicide programs can dramatically reduce inputs—up to 78 percent in certain cases—when paired with disease-resistant bentgrass cultivars. I explain how the researchers designed the field trials, what the low damage threshold means in practice, how 24-hour and next-application-day schedules performed differently, and why resistant cultivars such as Declaration produced such large savings without sacrificing control. I also discuss how inoculation affected disease pressure, why susceptible cultivars behaved differently, and what this means for superintendents trying to reduce fungicide use while maintaining high-quality fairways. If you want a clear, evidence-based explanation of how timing, cultivar resistance, and disease pressure shape fungicide performance, this video brings the science into focus.
🎓 Turfgrass Epistemology — How do we know what we know?
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Thank you for being part of this community and for supporting evidence-based turfgrass science.
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Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
Spotify Podcasthttps://open.spotify.com/show/1cTpdrChToeEFAOX9wkXFI
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Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf
Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

S3 E60 Biology and Management of Dollar Spot

In this video, I break down one of the most influential papers ever written on turfgrass pathology: Walsh, Ikeda, and Boland’s 1999 review on the biology and management of dollar spot. This paper remains a foundational resource for understanding how the pathogen operates, why the disease is so persistent on cool-season turf, and which management strategies are supported by evidence rather than tradition. I walk through the key sections of the paper, including the pathogen’s life cycle, the environmental conditions that drive epidemics, the role of cultural practices, and the strengths and weaknesses of common fungicide approaches. I also explain how the scientific understanding of dollar spot has progressed since 1999 and why many of the insights in this article still guide modern management decisions. If you work in turf management or simply want to understand the science behind one of the most costly diseases in the industry, this video will help you separate evidence from assumption and improve your decision-making.
🔬 Keywords: Dollar Spot, Bentgrass, Dew Removal, Nitrogen, Turfgrass Disease, Integrated ManagementDon’t forget to like, share, and subscribe to stay updated on more science-driven insights!
Become a member of Turfgrass Epistemology and support turfgrass research:www.youtube.com/@TurfgrassEpistemology/join
Voicemail:859-444-4234
Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
Spotify Podcasthttps://open.spotify.com/show/1cTpdrChToeEFAOX9wkXFI
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Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf

S3 E59 Tinfoil Turfgrass: Don't Use This Soil Test!

In this episode of Turfgrass Epistemology, I review a popular lawn-care website article and an accompanying YouTube video that teach homeowners how to interpret a soil test that is, in reality, scientifically invalid for making nutrient decisions. These resources look polished and authoritative, but the advice they provide is fundamentally flawed — and following it can lead to unnecessary product applications, wasted money, and incorrect assumptions about soil health.
I’ll walk through both the website and the video step-by-step and explain:
Why the soil test they promote is not valid for nutrient recommendationsHow certain companies use oversimplified or misleading soil interpretations to sell productsThe scientific standards for a real soil test and what makes it trustworthyHow proper soil testing differs from marketing-driven “DIY” interpretationsWhat homeowners should actually look for when deciding if their lawn needs fertilizer, lime, or amendmentsHow to evaluate online lawn-care information and avoid advice that is not evidence-based
The goal of this video isn’t to criticize people — it’s to highlight why bad testing leads to bad decisions, and how to empower homeowners with the ability to recognize valid, science-based soil information.
If you’ve ever wondered whether the soil advice you see online is trustworthy, or how to distinguish real science from clever marketing, this episode will give you a clear, reliable framework for making informed choices.
🔬 Keywords: Dollar Spot, Bentgrass, Dew Removal, Nitrogen, Turfgrass Disease, Integrated ManagementDon’t forget to like, share, and subscribe to stay updated on more science-driven insights!
Become a member of Turfgrass Epistemology and support turfgrass research:www.youtube.com/@TurfgrassEpistemology/join
Voicemail:859-444-4234
Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
Spotify Podcasthttps://open.spotify.com/show/1cTpdrChToeEFAOX9wkXFI
iHeart Radio Podcasthttps://www.iheart.com/podcast/1323-turfgrass-epistemology-129043524/
Podbeanhttps://turfgrassepistemology.podbean.com/
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Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf

S3 E58 Which Journals Can You Trust?

Not all scientific journals are created equal. Some exist to advance knowledge — others exist to collect publishing fees. In this episode of Turfgrass Epistemology, we explore how to tell the difference.
I’ll walk through the refereed process and explain how it differs from standard peer review, why that distinction matters, and how the structure of editorial oversight determines the credibility of the science that reaches the public. We’ll also take a close look at predatory journals — publications that mimic legitimate science while bypassing or corrupting the review process in exchange for author fees.
But the story isn’t as simple as “good” versus “bad.” Even in a predatory journal, a paper may contain sound science — the key is learning how to weigh the evidence and evaluate quality for yourself. We’ll discuss:
What defines a refereed journal versus a peer-reviewed one.
How to spot red flags in a publication or website.Why impact factors and indexing are useful but not foolproof.The difference between open access done right and pay-to-publish exploitation.Practical ways any reader — scientist or not — can assess a journal’s credibility.
By the end, you’ll have a framework for evaluating whether a journal’s claims deserve your trust — and how to apply critical thinking before citing, sharing, or believing “published” results.
If you care about how we know what we know, and why evidence must be judged as well as gathered, this episode is for you.
🎓 Turfgrass Epistemology — How do we know what we know?
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Thank you for being part of this community and for supporting evidence-based turfgrass science.
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Voicemail:859-444-4234
Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
Spotify Podcasthttps://open.spotify.com/show/1cTpdrChToeEFAOX9wkXFI
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Podbeanhttps://turfgrassepistemology.podbean.com/
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EmailTravisShaddox@gmail.com
Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf
Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

S3 E57 Does Trinexapac Reduce Dollar Spot?

In this episode of Turfgrass Epistemology, we take a close look at one of the most frequently cited studies in turfgrass pathology — Golembiewski and Danneberger’s 1998 Agronomy Journal paper exploring how trinexapac-ethyl (TE) and nitrogen fertility influence the severity of dollar spot (Sclerotinia homoeocarpa) in creeping bentgrass.
The researchers found that TE, a popular plant growth regulator, didn’t increase disease as many feared — in fact, it reduced dollar spot when combined with adequate nitrogen. This discovery challenged the prevailing assumptions of the time and suggested that growth regulation and fertility could work together to reduce fungicide reliance on golf course fairways.
In this discussion, we unpack:
The experimental design and methodology behind the study.
Why mowing height and growth regulation changed disease outcomes.
How nitrogen rate influenced both dollar spot suppression and thatch accumulation.
What this means for modern integrated pest management (IPM) strategies in turfgrass systems.
By the end, we’ll consider whether the mechanisms observed in 1998 still hold true today — and what this research can teach us about evidence-based turf management in the age of marketing claims and quick fixes.
If you enjoy videos that bridge science, history, and turf management, consider subscribing and joining the conversation.
Paper discussed:Golembiewski, R. C., & Danneberger, T. K. (1998). Dollar spot severity as influenced by trinexapac-ethyl, creeping bentgrass cultivar, and nitrogen fertility. Agronomy Journal, 90(4), 466–470. https://doi.org/10.2134/agronj1998.00021962009000040004x
🔬 Keywords: Dollar Spot, Bentgrass, Dew Removal, Nitrogen, Turfgrass Disease, Integrated ManagementDon’t forget to like, share, and subscribe to stay updated on more science-driven insights!
Become a member of Turfgrass Epistemology and support turfgrass research:www.youtube.com/@TurfgrassEpistemology/join
Voicemail:859-444-4234
Apple Podcasthttps://podcasts.apple.com/us/podcast/turfgrass-epistemology/id1717271379
Spotify Podcasthttps://open.spotify.com/show/1cTpdrChToeEFAOX9wkXFI
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Podbeanhttps://turfgrassepistemology.podbean.com/
Online consultingCalendly.com/TravisShaddox
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EmailTravisShaddox@gmail.com
Turfgrass Programs and Extension Service Information:https://www.usna.usda.gov/assets/images/as_pdf_image/LandGrantColleges.pdf