Frost is an interesting process that occurs on clear, cold nights. Frost forms when the turfgrass plants re-radiate or give heat off to the atmosphere (exothermic) causing a “cooling” effect of the turfgrass leaves. If the leaf temperature is lower (cooler) than the air temperature, then moisture from the atmosphere will condense on the turfgrass leaf (dew). Frost then forms when the temperature of the leaf drops below freezing (32 F) and the water on leaf freezes. Frost will occur even if the air temperature is slightly above freezing.
Frost formation on turfgrass leaves
Frost that has crystallized on the grass makes it hard and brittle. A grass blade is actually 90 percent water, therefore it also freezes. Because of the short mowing height (sometimes as low as 1/8 inch) and fragile nature of the turf, putting greens are most affected by frost. Walking on frost-covered greens causes the plant to break and cell walls to rupture, thereby losing its ability to function normally. When the membrane is broken, much like an egg, it cannot be put back together. Frost does not cause damage to the turfgrass itself, but rather turfgrass damage occurs when traffic occurs on these frost affected areas. The turfgrass damage is normally superficial. This is not to say that traffic should be allowed on frost affected turfgrass. Initially, the symptoms will appear as a purplish to black coloration of the leaves progressing to a brownish “straw” color. If the traffic is concentrated and damage occurs to the turfgrass crown, then recovery may not occur.
Another important factor to keep in mind is that a foursome of golfers typically takes several hundred steps on each green. By allowing even a few golfers to play when frost is present can be very damaging to the greens as well as other turfgrass areas on the golf course. So, frost delays are a requirement to protect the turfgrass and its health.
Foot traffic from one foursome of golfers on a golf green
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