In April, spring is on its way and the vegetation wakes up, so the winegrowers pay particular attention to the risk of spring frosts. We are at the dawn of a new vintage that the consulting oenologists will accompany.
There are two types of frost: advective frost, caused by the passage of a cold front (low pressure system or invasion of polar air) as in 2021, and the more common radiative frost, which results from the accumulation of cold air on the ground. After sunset, the ground loses heat accumulated during the day, warm air rises in the sky and denser and heavier cold air accumulates on the ground. We can then experience two types of frost: hoarfrost in wet weather which is characterized by a thin film of ice, when temperatures are around -1 to -5°C. In dry weather, it’s black frost with polar temperatures of – 2 to – 10 ° C.
The first precaution is to take out antifreeze insurance, the most effective way; but the most visible is the installation of anti-freeze towers, coupled with heat sources (gas burner or vegetable wax candles) distributed over the vineyard. The technique of sprinkling water on the twigs protects the bud in a cocoon of ice. However, this technique requires large quantities of water: pond or lake.