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About candles and bitter cold

Lost without frost protection in icy nights

Many envy Val Venosta’s apple producers these days. While most of us have to stay at home, they can work in their orchards. But wait a minute. Can? They have to work not only during the day but also at night to protect their orchards from crop failures due to Father Frost. This is why frost protection is on top of their priority list this spring. Today, we would like to answer the most frequent questions about this topic.

Why does ice protect from frost?

This is a good question because it seems paradox at first glance. When the producers turn on irrigation at night and the water freezes, energy is released in the form of heat under the ice layer. So the delicate apple flowers are protected, frost damages are averted and producers can hope for a good harvest. Besides, it’s a great spectacle because is there anything more beautiful than sparkling ice flowers in the morning light?

Where does the water for frost irrigation come from?

It’s a fact that frost irrigation is the most sustainable frost protection method. It produces no emissions and the producers try to use the water resources carefully. Most of the water comes from reservoirs and a smaller part equaling about 25% originates from so-called “Ziggln”, as deep wells are called in the local dialect. The precipitation and melt water from the reservoirs is diverted to the valley and thus seeps into the ground. When the ground is saturated, it goes back to the groundwater and so the cycle of nature is complete.
What if…
…there were no frost protection?
What if…
The moment of truth for producers comes in spring. If the delicate buds and flowers are damaged, the result can be a crop failure in the worst case. Spring frost at night is especially dangerous. Already temperatures around 0°C can result in great reductions in quality such as russeting of fruits or frostbitten flowers. And every frostbitten flower means one apple less and thus constitutes a growing existential threat for apple producers.

Do frost candles really work?

Yes, fortunately! Frost candles, also called paraffin candles, are set up in the orchards in case of icy temperatures. The warmth of hundreds of small fires rises the surrounding temperature by a few degrees to protect the young shoots and buds. Frost candles can burn up to eight hours and light up icy spring nights with their magic flickering.

Is frost irrigation not enough?

Unfortunately, it is not possible to use one method only in Val Venosta because some producers, especially those with orchards on slopes, have no access to water supplies necessary for frost irrigation. So frost candles are the only possibility for them to protect buds and flowers from cold damage. Some also use wood or wood pellets instead of frost candles.
How do you know…
…when frost protection is necessary?
How do you know…
That’s a very interesting question because producers are no clairvoyants, of course, and the weather forecast is not always reliable either. So there is a special frost warning service organized by the apple producers themselves: Two of them monitor the values of a measuring station of a certain frost area throughout the night. If a critical temperature is reached, they send an SMS alarm.

Nowadays, there even are early warning systems that activate frost irrigation automatically. Years ago, when they didn’t have these possibilities, the fire brigade sirens often howled in the middle of the night, which meant that the apple producers had to get up and turn on frost irrigation. Frost warning services, however, are not infallible despite the most modern technologies and are even more complicated in times of Coronavirus.


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