Climate change and its interaction with winegrowing

A Radio NZ article about University of Waikato student Electra Kalaugher and her work on climate change and dairy farms, and the accompanying video was particularly timely, because at about the same time I was answering a questionnaire sent to me by a student studying an MBA in Bordeaux. Her thesis is on climate change on winemaking and how it concerns the French legislation relating to the wine industry.

Below are her questions and my answers to them. My thanks to her for permission to post the information here...

1-Climate change has been affecting the wine industry, like all fields in agriculture. What is your experience in the vineyards of New Zealand so far?

Of those events that are supposed to be altered with climate change, in recent years I think we have seen wider swings in weather events, such as rainfall, snow, frosts and the like. We have had some periods of significant drought, as well as highly unusual heavy rainfall. We have seen some late season frosts, and unusually large amounts of snow in some areas. However, it remains to be seen whether these events are considered to be abnormal in the longer term.

2-Do you think New Zealand will benefit from the climate change since the warmer areas expand?

It is possible that new geographic areas will open up to winegrowing as a result of the overall warmer temperatures. However, this will have implications for the existing areas, where the warmer climate may mean that making wine styles associated with a particular region could be made more difficult. For example, the Marlborough style of Sauvignon blanc is associated with the cooler ripening period that the region has experience. If temperatures rise, the flavours in the wines will also change, and so the wine style.

This is one challenge, and another significant one is the chance of more extreme weather events. Of the possibilities, early season or late season frosts are a particular concern for the wine industry, as many areas are already prone to damaging frost events, so having them occur later into the growing season, and earlier as the season ends and harvest approaches, will have a direct impact on profitability.

Some forecasts for seasonal changes in precipitation point to less overall rainfall as a result of climate change in the eastern parts of New Zealand. Therefore, water will become an even more valuable resource, potentially limiting grape production.

Overall, I do not think that climate change will be a beneficial thing for the New Zealand wine industry, but the reality is that we will have to deal with it.

3-What are the challenges that the wine producers have been facing due to climate change effects?

I've mentioned some of these already - the possibility of frosts happening later in the beginning of the season and also happening before fruit is harvested. Water availability has been an issue with the establishment of newer vineyards, with water schemes needing to be developed to ensure a reasonably reliable water supply. Increased heat means that some grapevines will need to be grown slightly differently in order to retain the flavour profiles that are wanted in the wine. Severe flooding has had minor impacts on vines so far, but this will probably be more of an issue in the future.

4-What kind of changes should be made in the vineyards in order to adapt the shift in climate?

Viticulturally, it will be necessary to change the management of the vines to retain flavour profiles - for example, doing less leaf removal, or changing its timing. Trellising systems may need to be changed to help with this, as Vertical Shoot Positioning, which is the most widely used system in New Zealand, may give the fruit too much exposure.

Irrigation management (and linked with that, cover crop management) will have to be tweaked to ensure vines don't get water stressed at inappropriate times. More efficient ways of delivering water to the vines, and measuring soil and grapevine water status, need to be developed.

With frost events potentially happening when vines have more canopy on them, more efficient ways of dealing with frosts will be needed. If enough water can be found (which is unlikely for large vineyards), sprinkler systems will work, but most are using fans or helicopters at the moment, which rely on the presence of an inversion layer, which holds warm air. As well, it isn't certain how climate change will alter the occurrence and strength of inversion layers...

New vineyards should be planted with future shifts in climate in mind. This encompasses most aspects of vineyards, but also variety choice and potential wine styles to be produced.

5-As a viticulturist, what are your conclusions for the future concerning the climate change effects, for New Zealand and also globally?

In my mind at least, climate change is a reality that we should be ready for. Planning for its occurrence, using the latest forecasts (e.g. NIWA's Climate Change Scenarios for New Zealand), is the best we can do. 

The wine industry will be able to cope with climate change, but it will likely have an impact on the financial planning, with increased risk of crop loss and increased management costs. The possible changes to wine style also need to be considered carefully, as the consumer may want to stick with the current style, but it may not be able to be grown in the same area or it wouldn't be cost effective to do so given the extra labour inputs.

What's the weather doing this season?

The Growing Degree Days (GDD) figures for Lincoln through March 13th don't make for pretty reading!!

Currently we sit at 686 GDD (base 10, calculated on a daily basis) while the long term average (LTA, 1931 through 2010) to this point in the season is 812.

 Figure showing the growing degree days for Lincoln, Canterbury based on daily calculations at base 10C

December was the only decent month, having a heat accumulation close to that of LTA, but November, January and February were all cooler than LTA to the tune of about 85% of the value.

Rainfall is about aligned with LTA, the current season to March 13 being about 18mm greater than the LTA of 441mm.

Often, we get a nice March and early April after seasons where the early months' temperatures have been lower than average, but so far this doesn't look like it's happening, with the weather patterns seemingly stuck on cool and unsettled.

The Seasonal Forecast for New Zealand (http://www.niwa.co.nz/seasonal-climate-outlook-march-may-2012) indicates they are expecting more winds from the north-east, which for many of the growing regions in New Zealand, which are along the East coast of the country, means cooler temperatures.

When I look back at the pattern of heat accumulation for Lincoln Uni since the 1998-1999 season when I first arrived in Canterbury, this is the coolest season of them all, bar the 2000-2001 vintage. It's also been a remarkably consistently cool season, whereas in other years it tends to be warmer than LTA at first, then cooler nearer to harvest or vice versa.

So what does this mean for vintage? As long as the fruit stays free of disease (which we've been encouraging through an open canopy), we should be all right. Any opportunity to drop off crop that is tailing behind the average in terms of ripening is a good idea, as well as keeping the canopy open so the fruit dries out more quickly and also gets warming by the sun. We also have to hope that the night-time temperatures don't get too low, as this can be a signal for the vines to get ready for winter and start dropping their leaves! We've already had a couple of nights near 3C!

Our own vineyard, in which we're growing Pinot noir (and a bit of Pinot meunier) for sparkling wine is about 10km from the Lincoln Uni vineyard, but we're harvesting very shortly as the fruit is up to 19 Brix. In a season like this, this show the value of site selection (our vineyard is on the Port Hills and protected from the easterly (and cool) winds), good canopy management and end use of the grapes (sparkling wine, so they are harvested earlier). Of course, that isn't saying anything about how easy it is to sell the wine!

I suppose the good news out of all of this bad weather information is that the December temperatures were reasonably warm, which should mean we still have a decent initiation of flower clusters for the 2012-2013 vintage. 

At least we will have a promising potential to work with!!

Selecting the Right Clusters for Your Wine

This article will appear in the Wines of Canterbury Newsletter

"Quality is never an accident" - usually attributed to William Foster or John Ruskin

Colour change and ripening has begun in our grapes, and a lot of people start thinking about cluster thinning at this time. But have you stopped to think about why you're doing this? Here are some possible answers and few thoughts on each:

• To reduce the crop load

Yes, true. But it takes time and money to do this, and at the same time, you're reducing the amount of fruit harvested and paid for. There has to be more to it than this!

• To make the winemaker happy

At the recent International Cool Climate Symposium for Viticulture and Oenology in Tasmania, Richard Smart said the best time to start thinning your crop was just before the winemaker visited the vineyard, and the best time to stop was as soon as he left!

The best way to make the winemaker happy is to deliver high quality fruit in relation to what they are paying. Do all winemakers know enough about viticulture and the production of high quality grapes to be able to tell you what is and isn't right for the vines? Some do, but many don't. Their heads should be filled with all things winemaking, and viticulturists' should be filled with all things viticultural.

The best thing to do is get the winemaker to tell you what s/he wants from the vineyard's fruit, and for you to do what's necessary to have fruit that most closely meets those needs. Sometimes, removing lots of fruit is not the answer!

• To increase sugar accumulation in the fruit

If you go through a vineyard at veraison and remove fruit randomly, I doubt there would be much, if any difference in the harvested fruit composition - that is, the rate of sugar accumulation in the remaining fruit is no faster because you've removed some crop. I haven't seen any consistent and convincing evidence to suggest that removing crop randomly this late in the season brings harvest forward.

However, if we do commercial practice and remove that fruit which is not as ripe as the rest (in the left side of the figure below), then we're decreasing the variability of that fruit by removing the less ripe stuff, and thereby increasing the average ripeness of what remains. So what's happening there is removal the tail end of ripening fruit.

By doing this, you can increase the quality of the resulting wine, which is the overall goal of the viticulture-wine making pathway that we all travel along, and therefore the goal of crop thinning.

Because fruit are being removed selectively, and there will always be some fruit that lags behind in development, this form of thinning can be effective in improving wine quality in any season - particularly in cooler climates, where getting fruit to its optimum ripeness is a challenge.

But it doesn't stop there. If we want to maximise the quality of the wine made from the grapes, we need to ensure that only the best quality fruit ends up in the receival bin at the winery. This process continues on from crop thinning to monitoring the fruit and fixing problems before they arrive, so you have the greatest amount of harvestable crop possible. Things to think about here are:

• Removing leaves resting directly on clusters. Airflow around and if possible, through, clusters is a very important part of keeping Botrytis at bay! Leaves on top of, or resting next to, clusters keeps the environment more humid and for longer, which is what Botrytis needs to germinate and infect.
• Similarly, arranging clusters so they are not draped on top of one another. Multiple clusters trying to occupy the same space mean restricted airflow and poor exposure to the sun, leading to greater disease risk and less ripe flavours. The best time to combat this is even a few weeks after fruit set, when it's easier to separate clusters and try to arrange them so they don't touch. If you can't keep them from sitting on top of one another, take the short term loss by clipping off of one of the clusters rather than doing nothing and having the real risk of losing all the fruit to rot.
• Cutting out clusters or parts of clusters damaged or diseased. Physically damaged fruit can, and usually does, harbour Botrytis - something most evident when a couple of weeks ago I took a few split berries i found in the vineyard (like those pictured below)  and incubated them in high humidity conditions for a day or two. Lots of fungal growth appeared from the damaged areas, but none from the intact parts of the berry. As well, fruit that has a bit of Powdery Mildew on it can split when the berry starts to ripen, inviting Botrytis and other rot organisms. Once it's in and established, it's much more likely to spread around.
  
  
  
  
  
• If you're machine harvesting, have a crew go through beforehand to remove any second set crop that might also be harvested, because even a small amount in a load can have a significant effect on wine flavour. As well, have them take out any diseased or sunburnt fruit, as these can lower the quality of the wine. Monitor their work for slips and keep them on the right track.
• If you're hand harvesting, the best time to sort grapes is in the vineyard, not on a winery sorting table. Why pick and transport poor quality and diseased fruit, only to discard it at the winery? You make more work for yourself, and increase the risk of spreading the disease around. Make sure your picking crew is well trained to leave the undesirable fruit, and check on them periodically to make sure they continue to do it right.

While this is all sound advice, I'm not trying to say that it's right for everyone. For some wine products, this level of attention to detail is not warranted - there just isn't the payback to justify it. However, if you're thinking about quality first, then every little bit counts. There isn't one, single, management decision that will deliver quality to the winery - it's a series of actions that contribute to the health and suitability of the harvested crop that makes the difference...