Høst og frost

Vi nærmer oss sesongslutt, men håper på mange fine golfdager før dette. Frost, spesielt på morgenen har vi allerede opplevd. Frost vil vi få i tiden fremover. 

Det som skjer når du går på gress med frost, er at du knuser cellene. Du dreper gresset, og det vokser ikke tilbake igjen på lenge. Skaden kommer ikke til syne med en gang, men det kan bli veldig tydelig i dagene etterpå. Vi vil derfor holde anlegget stengt når forholdene tilsier at gresset bør få ro og ikke bli "brukt" av ivrige golfere. Informasjon om dette gjøres fremst på våre Facebook-sider.

Nedenfor er det litt informasjon om gress og skader som kan/vil oppstå når det er aktivitet på en frossen bane.

Damage from playing on golf greens with frost or frozen soil (By Dr. Leon Lucas) 

Play is often delayed on courses during the winter due to frost on golf greens. The reason the club should not allow play on greens that are covered with frost is that the turf will be damaged from walking on the frost. The ice crystals in the frost can puncture the leaves from foot pressure. The damage will appear as footprints later in the day and will be present until the turfgrass grows out of the damage. The damage may be evident for several months and result in weaker turf in the spring in the area around where the hole was on the day frost was present.

Deciding when to allow play on greens with frozen soil is more difficult to determine. The greatest damage occurs to the turf when the top layer of soil thaws while a frozen layer remains deeper in the soil. The thawed layer will be saturated with water and becomes spongy. Walking on turf with this condition will cause foot printing and can cause the surface of the green to become uneven. Severe turf damage can result from shearing off the roots as the turf moves above the frozen layer. This damage in areas around where the hole is located on these days will appear as weaker turf later in the year.

It is difficult to explain to golfers that they should not play on greens that are thawing during a warm and sunny day following very cold weather. Golfers are eager to return to the course on the nice days following long periods of cold weather. All greens usually do not thaw at the same time. Shaded greens are the last to thaw and more damage often occurs on these greens because it is difficult to keep golfers off the course any longer.

Frost is a form of ice and can only survive at temperatures of 0 degrees Celsius and below. But that doesn’t mean the measured air temperature must be 0 or below for frost to form on a surface. Green grass, for example, absorbs sunlight and heat during the day, then loses heat when the sun goes down, so the grass’s temperature may be lower than the surrounding air temperature. This temperature differential causes moisture to condense on the grass during the night. If the temperature of the grass then falls below freezing, the moisture may crystallize into frost. This can occur even when the nearby air temperature is close to, for example, 4 degrees Celsius, particularly when the air is calm.

When and Where Frost Occurs
Frost may occur overnight, but it often forms at sunrise, before the temperature begins to rise. Frost formation on grass is possible in any location in which the blades’ temperature falls to 0 or below. For example, overnight frost may form even on days when the high temperature reaches 21 degrees Celsius. 

Damage to Grass
Frost itself doesn’t damage grass in the way that it may damage other growing things, such as citrus fruit. However, golfers walking on frosty turf may harm the grass quite badly. Because the grass on putting greens is cut so low, around 4mm, it is particularly vulnerable to damage when it’s covered by frost. When a golfer walks on frost-covered grass it is more likely than normal to break and suffer ruptured cell walls.

Delayed Impact
The damage caused by walking on frost-covered grass may take two to three days to appear. By that time the damaged blades may turn purple or black, eventually fading to a very light brown. If the plant’s growing point is undamaged, however, the grass should regenerate. If the growing point is damaged, the plant may die. Additionally, weaker grass, even if it doesn’t die, may be more susceptible to disease and weed formation.

On behalf of our members, we Greenkeepers aim to get the day started as early as possible whenever there is a frost in the mornings. Importantly though, it is our professional responsibility to consider the long-term health of the course. Therefore, when considering the frost dilemma, the Greenkeeper's decision must be respected.