Have you heard about sunscreen for grapes?

Published on 03/26/2021 by Priscilla Hennekam

The first time I saw white vines due to sunscreen, was here in Barossa Valley, at the first winery where I worked. I was very impressed with this whole idea, so I have done a lot of research on this topic, and today I would like to share a little bit of this knowledge with you.

"You put sunscreen on your kids when they go out in the sun, so we put it on our grapevines. That just goes on like a normal spray", says Bruce Tyrrell, the chief executive of Tyrrell's Wines.

Tyrrell is a winery located in Hunter Valley, NSW, Australia, that has been producing wine since the 1860’s. Mr Bruce Tyrrell realized several years ago that he would need to find ways to ensure that his grapes could survive in Australia's increasingly hot and dry climate. Then, over five years ago, the winery decided to adopt the so-called “Agricultural Sunscreen”.

So what is “Agricultural sunscreen”?

To start, let's talk about the ozone layer above Australia, which has a strong impact on the UV rays transmitted to the grapes. Australians have known about a “hole in the ozone layer above Australia” for years. Technically, the ozone layer around the mid-latitude is depleted above Australia, and a hole often occurs above Antarctica during Spring. The result of both of these, for Australia, is more UV radiation reaching the Earth, which is why many winegrowers take the decision to protect their vines with “Agricultural Sunscreen” in the years where temperatures exceed 45 degrees Celsius.

Very high temperatures can cause serious damage to the vineyards, and fruit can shrivel or suffer sunburn. High temperatures can also affect the ripening of the grapes - if the vine suffers from too much heat it begins to transpire a lot, so to protect the plant from running out of water it can stop photosynthesis, thus stopping the ripening of the grapes, making the harvest period longer or causing harvests with bitter flavours because of the lack of ripe grapes. All of these impact on the quality and yield of the vineyards.

One of the best practices to combat this problem in the vineyards is the use of a kaolin clay-based sunscreen, which helps to reflect direct sunlight or UV light, thus protecting the fruit from sunburn and damage caused by thermal stress.

According to wine grower and agronomist Warren Burgess from Langhorne Creek, Australia:

"With the range of practices that we have started to employ here, we're finding that we are mitigating some of that risk associated with some of these extreme days."

Australia once again surprises with their viticulture practices, guaranteeing the quality of its wines even in difficult years.