Late frosts puts a chill on California vineyards by Kirsty McCabe
April was a cruel month for California winemakers, bringing a series of unusually late frosts to vineyards baring the tender, green shoots of spring. The damage is still being assessed and it could be June before growers know the full extent, but most expect a smaller than average harvest this year.
The frosts hit the whole of Northern California, including Mendocino and the Napa Valley. Sinking temperatures dragged growers out of bed as frost alarms on vineyard thermometers went off. Frost is hardly unusual in California and in some years it can be severe, what distinguishes this season is the duration and severity of the frost. The cold snap lasted twenty or more nights in some places, and this was a first for many vintners. The last time such a brutal spell of frost occurred was over thirty years ago.
The cold snap’s immediate effects can be seen in some vineyards, where leaves that normally would be fluttering pale green in spring breezes are curled up brittle as December leaves.
Farmers have a couple of options for fighting frost. Wind machines can keep low-settling cold air off vines and move in the warmer air. Irrigation is also used to deposit a thin layer of ice over buds, which actually prevents the buds from falling below zero degrees Celsius.
