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Napa winemakers using clay ‘sunscreen’ on vine leaves

The latest weapon in the fight against climate change could be kaolin clay, with at least one Napa winery using the natural substance to shield its grapes from the sun.

Just as slathering on an SPF can help to keep human skin safe from harmful sun rays, a chalky white clay solution sprayed directly onto vine leaves can help protect grapes in sizzling temperatures.

Green and Red Vineyards in Napa’s St. Helena began spraying a natural clay solution onto the leaves of its Zinfandel grapes earlier this summer, when temperatures in Napa Valley reached unusual peaks of more than 100 degrees.

The spray, made up of kaolin clay, is said to protect the leaves, which in turn protect the fruit underneath, giving the canopy and grapes an extra layer of much-needed protection.

“It’s just like a sunscreen on a human,” Ray Hannigan told NBC Bay Area.

It’s just one of many techniques winemakers are using to deal with the increasing effects of climate change in the famous wine-growing region. A more expensive option than clay “sunscreen” is to cover vines with shade cloth, or even replant rows of vines so that they lie parallel to the sun, catching fewer of its scorching rays during the hottest part of the day.

Studies in Australia have also shown the clay product to be effective in reducing the temperature of berries.

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