Turfgrass Epistemology

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:

🔬 Keywords: Dollar Spot, Bentgrass, Dew Removal, Nitrogen, Turfgrass Disease, Integrated Management

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In this episode, I sit down to talk about a topic that’s been at the heart of American higher education for more than a century — university extension. We’ll explore how extension began, why it was once the lifeblood of land-grant universities, and how the system that connected science to society is now quietly disappearing.

Extension was created so universities could serve the public — not just by publishing papers, but by helping real people solve real problems. For decades, that mission worked. Faculty were rewarded for outreach, and industries like turfgrass, horticulture, and agriculture thrived because science and practice were linked. But somewhere along the way, the incentives changed. Grants, graduate students, and publication counts became the metrics of success, and the outreach mission — the reason land-grant universities existed in the first place — started to fade.

In this conversation, I reflect on when that shift began, what caused it, and what’s been lost in the process. We’ll talk about why extension matters, how it can be revitalized, and what universities risk when they stop valuing public service. My goal isn’t nostalgia — it’s to remind us that progress and connection don’t have to be opposites.

🎙️ Episode title: The Rise and Fall of University Extension

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Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

Can something as simple as mowing time really stop a turfgrass disease? In this episode of Turfgrass Epistemology, we look back at a landmark 1996 study by Williams, Powell, Vincelli, and Dougherty from the University of Kentucky — a paper that changed how superintendents think about dew, nitrogen, and dollar spot control.

Dollar spot (Sclerotinia homoeocarpa) thrives on leaf moisture. Williams et al. tested what happens when you simply remove that moisture early in the morning. Their data were stunning — mowing or “poling” to knock dew off reduced dollar spot by as much as 81% on fairways and 53% on greens. That’s before any fungicide was even applied. Add moderate nitrogen fertilization, and disease pressure dropped even further. Clipping removal, on the other hand, didn’t matter much.

This episode explores what these results mean for modern turf management. How does dew act as a bridge for fungal infection? Why does nitrogen strengthen bentgrass against disease? And what does this tell us about integrating simple cultural practices with fungicide programs? Join Dr. Travis Shaddox as we revisit this foundational study — proof that sometimes, the mower is mightier than the fungicide.

📘 Source: Williams, D.W., A.J. Powell Jr., P. Vincelli, and C.T. Dougherty. 1996. Dollar Spot on Bentgrass Influenced by Displacement of Leaf Surface Moisture, Nitrogen, and Clipping Removal. Crop Science 36:1304–1309.

🔬 Keywords: Dollar Spot, Bentgrass, Dew Removal, Nitrogen, Turfgrass Disease, Integrated Management

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In this video, I explore the history and current state of university turfgrass programs—from their rise during the post-war boom in golf, parks, and sports fields to their decline in recent decades. I explain how turfgrass faculty positions are created and filled, what factors lead to the loss of those positions, and why many programs are now disappearing altogether. I connect the dots between enrollment trends, industry funding, and the shifting priorities of universities that have left turfgrass science struggling to survive. Most importantly, I discuss what the turfgrass community—educators, managers, and industry leaders—can do to reverse the trend and rebuild the academic foundation that once supported innovation in turf management. This episode blends history, data, and reflection to uncover how we got here and what it will take to bring turfgrass education back.

In this video, I examine the 2021 study by Beckley and Roberts published in the International Turfgrass Society Research Journal titled “Utilizing Organic Amendments for General Suppression of Dollar Spot on Creeping Bentgrass.” The discussion centers on one key question: Does biochar actually reduce dollar spot? I break down the experimental design—how researchers compared biochar, compost, vermicompost, and traditional fertilizers under equal nitrogen rates—and explains what the data really show. Were the reductions in dollar spot due to microbial changes, or simply better nitrogen nutrition? You’ll see how biochar performed across two years, why the results were inconsistent, and what this means for turfgrass managers trying to reduce fungicide use. The episode also explores the broader implications for integrated disease management and the growing interest in “natural” amendments. If you’ve ever wondered whether biochar is a biological breakthrough or just another overhyped input, this deep dive into the data will help separate evidence from assumption.

https://doi.org/10.1002/its2.55

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In this video, I explore the recent review article “Review of the Biology and Management of Large Patch of Warm-Season Turfgrasses” (Kreinberg et al., Crop Science, 2025). I walk you through what the authors tell us about Rhizoctonia solani AG 2-2 LP — the fungal pathogen behind large patch disease in warm-season turfgrasses — how environmental conditions favor its development, and how it can persist in thatch through seasonal dormancy. Along the way, I highlight the state of current cultural, chemical, and biological control strategies, and I point out the gaps and future directions the turfgrass pathology community still needs to address. If you’re into turf disease management, plant pathology, or sustainable approaches to keeping turf healthy, this discussion is for you.

https://doi.org/10.1002/csc2.70055

📌 https://www.gofundme.com/f/TurfgrassEpistemology

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Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

In this video, I take you through the state of the science on dollar spot disease in turfgrass, framed by the recent review “New Approaches to an Old Problem: Dollar Spot of Turfgrass.” We explore how this ubiquitous fungal disease (caused by Clarireedia spp.) continues to challenge turf managers, why traditional fungicide programs are increasingly under pressure, and what new genomic tools and breeding strategies may offer as solutions. I’ll break down the authors’ discussion of pathogen genomics, host–pathogen interactions, and quantitative trait loci (QTL) for resistance, while also reflecting on where future research might be headed. Whether you’re a turfgrass scientist, practitioner, or just curious about plant pathology, this video gives an accessible, evidence-based look at tackling a persistent problem in turf management.

https://doi.org/10.1094/PHYTO-11-20-0505-RVW

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In this video, I dive into the article “Survey of Water Use and Management Practices on US Golf Courses from 2005 to 2024” published in HortTechnology (Shaddox et al., 2025). The study tracks nearly twenty years of changes in how golf courses across the United States use and manage water. I discuss how irrigation volumes and irrigated areas have shifted over time, highlight important regional differences, and explain why some water sources—like recycled water—are declining while others remain steady. I also cover the adoption of new management strategies such as moisture sensors, irrigation audits, and objective scheduling, along with the continuing challenges of infrastructure upgrades, regulatory pressure, and competition for water resources. If you’re interested in sustainability, turfgrass science, or the future of golf course management, this discussion will give you a clear look at the evidence and what it means moving forward.

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In this video, I discuss the YouTube episode “Struggling Turf? Calcium Could Be the Missing …” and examine it through the lens of the strawman fallacy. We’ll look at how someone can present information that is technically true, yet still mislead by reframing the issue or knocking down an argument no one actually made.

This breakdown shows how a conman can be both truthful and deceptive at the same time—a powerful reminder of why critical thinking matters in turfgrass science, lawn care, and beyond.

If you’ve ever learned something useful from this channel, please consider contributing. Every donation—large or small—helps strengthen the future of turfgrass research.

📌 https://www.gofundme.com/f/TurfgrassEpistemology

Thank you for being part of this community and for supporting evidence-based turfgrass science.

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Diagnostic Criteria for Turfgrass Bullshit Disorder:https://drive.google.com/file/d/1Y_GeVPQ237pzm0ImTP4eVij6I9D0PHPn/view

In this video, I review the scientific article “Irrigation Frequency Affects Zoysiagrass Rooting and Plant Water Status.” We’ll look at how different irrigation schedules influenced root development and water relations in zoysiagrass, and what these findings mean for turfgrass management. If you’ve ever wondered how often you should water to encourage deeper roots and better turf performance, this study offers valuable evidence-based insights.

Article: https://journals.ashs.org/view/journals/hortsci/31/2/article-p234.xml

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