RattleSnake Turf Update - July
11 JUL 2025
Turf Newsletter – July 10, 2025
Heat Stress and How We Manage During the Dog Days of Summer
Just as we feel the impact of extreme heat, so do our turf grasses. While we hydrate, seek shade, wear hats and sunscreen, and cool off with air conditioning, even these precautions can fall short. When that happens, we may become lightheaded, fatigued, or even require medical attention.
The same principle applies to our turf. In Southern Ontario, we predominantly grow cool-season grasses—mainly bentgrass and Kentucky bluegrass. These species are well-adapted to survive harsh winters and thrive through most of the summer. However, during the longest, hottest days of the year, they struggle. At a certain point, they effectively say, “Enough is enough,” and begin to shut down.
We walk a fine line when managing turf during these extreme heat periods. Here are some of the key strategies we use:
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Preparation is Key: We head into heat spells with healthy turf—minimal stress, appropriate fertility levels, fungicides applied for maximum efficacy, wetting agents functioning at peak levels, and a well-managed irrigation plan.
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Limited Night Irrigation: We avoid using overhead irrigation at night whenever possible. Prolonged leaf wetness increases the risk of fungal diseases. While morning dew is removed early through mowing and rolling, we don’t want to compound that moisture with night watering. We’re also cautious of sprinklers malfunctioning and flooding a green (more on that in a future update).
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Targeted Hand Watering: Early morning hand watering is followed by light syringing throughout the day to cool leaf surfaces. We use soil moisture meters to monitor volumetric water content, aiming for a sweet spot between 15% and 20%. Too little or too much moisture can lead to root death and canopy decline. Oversaturation creates anaerobic conditions, depriving roots of oxygen—and without oxygen, roots die.
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Pin Rotation for Plant Health: Moving pins daily not only provides variety for players but also helps reduce stress on the turf. Foot traffic—especially from 400+ golfers in cleats—takes a toll, so we do our best to spread that wear around.
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Reduced Mowing and Rolling: During heat stress, we scale back double or triple cuts, limit cleanup passes, and reduce rolling frequency to lessen the strain on the grass.
Even with thorough preparation and careful management, sometimes Mother Nature takes the wheel. Our most recent stretch of weather included 35°C days, high humidity, strong winds, and warm nights, capped off with two intense thunderstorms. Despite our efforts, the greens experienced some slight decline. The same was true for members of our turf team—some of whom suffered from heat-related illness despite their own precautions.
As we move through these challenging weeks, let’s all do our part. Stay hydrated, nourished, and cool out there. Play a bit of defense on the course—and I promise to do the same for our greens.
Stay safe and cool,
Bill McAllister
Golf Course Superintendent
RattleSnake Point Golf Club