5 years ago
Sunday, May 1, 2011
Frost season comes each year unfortunately
Through the bloom stretch frost can be a challenge. It seems to come every year, although some years it visits only a couple days while other years it drags on way too long. While the blossom is dormant through the winter it is susceptible to damage by cold temperatures, but usually only extreme temperatures will kill the blossom. During the prebloom when the bud swells and the flowers and leaves begin to show they become more susceptible to the cold. Eventually we try to keep the orchard from falling below the freezing threshold. It is challenging to raise the temperature in the orchard, but usually it can be done. The different methods enable us to get a few degrees of warming and that generally is enough. Water as in the first picture may seem backward but actually works really well to help warm the air. Water as it cools and makes the jump to becoming ice releases energy in the form of heat. The one drawback is the need for a constant supply of enough water for the area you are trying to save. Wind Machines like the one below also work well. Many people do not understand the term wind chill, the term refers to the rate of heat loss. In other words if the wind chill chart said it was 10 degrees colder than the ambient temperature then you will lose heat as if it were the 10 degrees colder, but the air is still exactly what the thermometer says. The buds don't care if the wind is blowing as long as the actual temperature is above freezing. The damaging frost nights almost always occur when the air is calm. This allows the air to separate and the warmer air rises while the colder air builds near the ground. The cold air moves in the same manner as water will slide along the surface to the low areas and pool up there. A wind machine will move the warmer air above and push out the cold air settled near the ground. It is a large propeller which moves a lot of air and also rotates slowly making a complete circle about every 2 minutes. Yes, they do make quite a bit of noise, the blades sound somewhat like a helicopter and the motors have about 2 feet of straight pipe on them so you hear the motor well too. They cover around 10 acres depending on how calm and cold the night is. The last picture involves a strategy. Some nights there is a drift to the air and it is difficult to keep the cold air out. To counter this I will try to run water on the side of the orchard the air is entering. Some orchards have smudge pots (diesel heaters) or propane heaters or some are burning straw or other types of bales to heat the border. All these methods work but it is a difficult situation. All in all it makes for a long night. Such has been my life for the past while. I hear people from time to time who think that all a farmer does sit and watch the crops grow and have no idea the effort it takes and that those crops actually end up in a grocery store. After all, food comes from the store so what do we need farmers for?