Stopping a Tiny Fungus Before It Strikes
A deep dive into the science of protecting pristine turf, where timing and technique are everything.
Imagine a perfectly manicured green, the kind you see on a golf course putting green or a prized lawn. This emerald carpet is often a grass called creeping bentgrass, prized for its dense, velvety texture. But this perfect turf is under constant threat from a microscopic enemy: a fungus known as Sclerotinia homoeocarpa. This pathogen is the cause of Dollar Spot, a disease that manifests as small, straw-colored, circular patches the size of a silver dollar . Left unchecked, these patches can merge into large, unsightly blights, turning a beautiful green into a blotchy nightmare.
For turf managers, the battle against Dollar Spot is relentless and expensive. The key to victory, however, isn't just about what chemical you use, but how and when you apply it. Recent scientific research is revolutionizing this fight, showing that a pre-emptive strike, using just the right amount of "ammunition," can be the most effective and environmentally conscious strategy of all .
To understand the breakthrough, we first need to grasp two key strategies in plant medicine:
This is a treatment applied after you see the first signs of disease. It's like taking an antibiotic after you've already gotten sick. The infection is halted, but some damage has already been done.
This is a treatment applied before the disease appears. It's like getting a vaccine; the plant is protected in advance, preventing infection altogether.
For decades, the standard practice was often curative. Managers would see the first dollar spots and then spray a fungicide. However, scientists began to question this. What if you could apply a fungicide at the very first sign of infection—so early that it's still considered "curative" but acts almost like a preventative measure? This concept is known as "early curative" control . The question then became: what is the most effective way to execute this early curative strike?
To answer this, researchers designed a meticulous field experiment on a plot of creeping bentgrass. Their goal was to test how two critical factors influence the success of an early curative fungicide application: Spray Volume and Application Timing .
The scientists set up their experiment like a carefully controlled military operation:
A large area of creeping bentgrass was divided into many small, identical plots. This ensured that any differences in results were due to the treatments, not the turf itself.
A common and effective fungicide (in this case, a mixture of chlorothalonil and thiophanate-methyl) was selected as the "weapon."
They tested two different "doses" of water to carry the same amount of fungicide:
Application timing was tested at different stages of disease development: Preventative (1 day before), Early Curative (1 day after first spots), and Late Curative (7 days after first spots).
For weeks afterward, the researchers regularly counted the number of Dollar Spot infection centers on each plot. Fewer spots meant a more successful treatment.
The data told a compelling story. The visualizations below summarize the core findings from the experiment.
Average number of infection centers per plot, 14 days after application
Early curative application only
Combined effect on disease control efficacy
The ultimate takeaway is that you can achieve a level of control nearly as good as a full preventative program by combining an early curative timing with a low-volume application. This synergy is the key to the new approach.
What does it take to wage this war on Dollar Spot? Here are the key tools and reagents from the featured experiment.
The "battlefield." Provides a uniform, living surface to test treatments under real-world conditions.
A "contact" or "protectant" fungicide. It acts as a protective shield on the leaf surface, preventing fungal spores from germinating.
A "systemic" fungicide. It is absorbed by the grass and moves within its tissues, attacking the fungus from the inside.
The "precision delivery system." Designed to apply a fine, concentrated mist of fungicide, ensuring thorough canopy penetration without runoff.
The "intelligence report." A standardized square used to count and measure disease patches, providing objective data for comparison.
The science is clear: in the fight against Dollar Spot, vigilance and precision are your greatest allies. The old method of waiting until the disease is widespread and then drenching the turf is inefficient and less effective .
The new paradigm of Early Curative Control with Low-Volume Application offers a powerful alternative. It allows turf managers to:
By acting early and using concentrated sprays, less product and water are needed overall.
Better coverage and timing lead to superior disease suppression.
This approach aligns with Integrated Pest Management (IPM) principles, minimizing environmental impact.
So, the next time you walk across a flawless green lawn, remember the invisible, scientific battle that keeps it that way—a battle won not by brute force, but by smart strategy, perfect timing, and a perfectly calibrated mist.
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