Protecting high-value crops from the frost

Spring frosts are one of the worst threats vineyard owners face.

Frost damage is devastating not just for the producer but the wider industry too, as smaller crops often mean less for the pickers, the contract wineries, the packaging and labelling suppliers, and retailers too.

While the best way to prevent damage is to ensure the right varieties of vines are planted on the right frost-free site, growers have long needed to adopt other methods to mitigate the impact inflicted on young buds when the temperature drops.

One of the oldest methods used to protect vines is by heating the air in the vineyard.

Many UK growers have adopted the traditional French practice of placing and lighting bougies, however, these require a significant amount of labour to set them out and light them (often during the small hours of the night).

Those looking for a more efficient approach have long chosen to use the Frostbuster and Frostguards from Agrofrost.

Unlike other frost protection systems, the working principle is not based on raising the temperature above the critical values but on phase transition and controlling the forming of hoarfrost which is the biggest enemy for flowers and buds.

Without protection, the layer of hoarfrost will increase and finally cause damage to the plant by dehydration as the ice crystals extract energy and humidity from the buds and flowers.

The Frostbuster and Frostguards, which are supplied to UK growers by leading viticultural machinery specialists NP Seymour, form a hot air stream every seven to 10 minutes, so part of the ice evaporates while the remaining ice gets energy from the passing air.

The higher the humidity, the more energy is transferred. This allows growers to protect crops with only a fraction of the energy input that is needed by other systems.

The Frostbuster works by burning gas to provide a heated air supply, which is then blown by a tractor-driven fan. By driving around the vineyard following a pre-determined route, it is possible to protect an area of up to eight hectares.

It allows growers to protect crops at sites where no water is available and can be used not only during radiation frost but also during wind frost.

Alternatively, the Frostguard is a smaller, stationary version of the Frostbuster, featuring a petrol engine-powered fan which can rotate 360° continuously, to protect up to one hectare of vines.