Cold temperatures in fall and winter often result in frost formation on turfgrass. Here is a brief quiz to test your knowledge when it comes to the facts and fallacies concerning frost.
Frost can form on grass when the air temperature is above freezing.
Fact. Frost formation is a combination of several factors, including air temperature, dew point, slope, wind, and cloud cover. Because cold air settles, air temperature at the soil surface is much different than at eye level or the thermometer on top of the weather station.
Traffic on frosted turf will kill the plant.
Fallacy. Ice crystals from frost can sometimes puncture turfgrass leaves and cause some discoloration, but rarely does it kill the plant. Frozen turf–when the plant is completely frozen inside and out–is susceptible to winterkill from traffic, especially when the crown area is damaged. The tricky part for superintendents is determining if the turf is frosted or completely frozen and how much risk there is of turf damage if the course is opened to play.
There tends to be more frost on clear, cloudless nights.
Fact. Clouds act as a blanket in the atmosphere to trap heat escaping from the soil surface. On clear nights, the heat escapes without any barrier, causing surface temperatures to cool more rapidly.
The best way to melt the frost faster is to apply water at sunrise.
Fallacy. Just because the sun is up, temperatures at the soil surface can still be below freezing. Applying water at sunrise can result in more frost and ice formation if surface temperatures are 32°F or lower. As many superintendents have learned from experience, it is best to let the sun melt the frost naturally.
The temperature is always coldest before dawn.
Fallacy. It’s not unusual to have a frost-free golf course as maintenance begins before dawn then see frost everywhere after the sun rises. As the sun rises, surface and air temperatures are still falling and can blanket the golf course in frost when dew is present.
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