Thoughts on vine density

A student asked this question today, and I spent some time on a reply. A good topic for discussion (and final exam questions??? :-)

"Can you explain why low potential soils need closer vine spacing to optimize the yield and quality and soils with higher potential need wider vine spacing?"

"My understanding is that higher soil potential leads to high vigour of the vine and should increase the density of the vine to manage that right? So therefore high potential soil should have closer spacing than the low potential soil."

My answer:

Vine spacing is one of those things that you should really try to get right when you're planning the vineyard. It's one of the reasons why detailed soil surveys are done before vineyards (incorporating variety, trellis, rootstock etc.) are designed. Get the spacing too tight, and the vines will outgrow the volume of space available to them. Get it too sparse, and the vines may not be able to take advantage of the volume allocated to them, leading to unused cropping potential.

To begin this discussion, we should first define what we are talking about. There are two types of spacing: within row (between vine) and between row.

Generally speaking, as you decrease the between row spacing, you also decrease the between vine spacing. However, there is room to move, so to speak, when practicing this.

Firstly, let me tackle the question of soil qualities and appropriate vine density (which, through altering between row and within row spacing, is what we are mostly talking about here).

If a soil is fertile, then there are two trains of thought. One is to give the vine a lot of space to express its high capacity for growth - therefore, low vine density or wide spacings.

The other is to plant with high density to get the vines competing with each other for nutrients and water.

If the soil is not very vigorous, then there are the same trains of thought. Have wide spacings and low vine densities because the vines will then have little competition (assuming weeds are kept under control) and therefore access to the most water and nutrients that they can.

This sort of spacing is used in dryland farmed areas, where irrigation not feasible. The vines are trained as bushes, with perhaps only a stake for support. Because of this, yields per hectare are low, but then at least you can get something off the land - it's just not an intensive producing area (the most planted vine data I showed in my cultivars lecture demonstrated this - Arién has the most area planted to it, but the vine density, and therefore yields, would be very low compared to some other varieties).

Or, if you can add water to the equation, you can plant them closer together so that you can get a continuous canopy and therefore more productivity per unit area of land.

So determining the appropriate vine density depends not just on the soil, but also how it's going to be managed. The question referred to this as optimising the yield, which is the key.

So, with that out of the way, let's talk about vine spacing in terms of what is practiced in the Old World versus the New World (using gross generalisations here, so please bear with me...)

In the Old World, some of the best wines come out of vineyards that are planted at around 1mx1m, or 10,000 vines per hectare. This compares to the usual 3mx2m spacings (1667 vines per hectare) in most of the early New World plantings, including a lot of Marlborough Sauvignon blanc (I assume everyone is familiar with how those spacings came about??).

The reasoning used by some is that because great wines come off of vineyards with close spacing that it must be the close spacing that contributes to that wine quality. Therefore, if we replicate that spacing in another place, we will get better wines.

However, as reasoned above, it's actually a balance of the soil and overall management that really results in achieving vine balance (open canopies and an appropriate ratio between fruiting and vegetative growth), where it's easiest to get the most quality out of your fruit. What often happens when close spacings are transplanted to another area is that the vines end up being vigorous and turn into a mess of shoots and canes that would send Richard Smart into conniptions!

Why does this happen? Well, in many New World areas, the soils are a lot more fertile and deeper than soils in the Old World, where they have been farmed for centuries (and are often on hillsides). It's true that close vine planting will result in root competition to the sides, but what if the soil is deep? The roots can grow down and away from competing roots and fine plentiful nutrients and water. Therefore, they grow like triffids, and viticulturists may resort to pulling out rows and vines to get it into balance. We just can't control growth of roots down into the soil - unless rainfall is low, and irrigation is used...

And that last point is really the crux to the discussion: viticultural management can alter what might not be the best vine spacing into a system that still produces optimum fruit. If the spacing is too tight and vines are growing out of the volume allocated to them, we can reduce irrigation, or plant a more competitive cover crop, make the weed-free strip under the vines narrower, change the training system, or, if it's dire, rip out some of the vines...

In practice, this happens all the time - though we try to get as much information as possible pre-planting, we are still just making a best-guess as to the vineyard setup - the best way to know how vines will perform in an area is to plant some and see how they go over a 10-15 year period. This is why vineyard redevelopment, as we have see in many areas due to phylloxera, for example, is really an opportunity.

Significant advances in grape processing

I recently came back from helping take Lincoln University's HORT212 (Viticulture I) class around Marlborough for two and a half days, looking mostly at vineyards, but also including a very good tour through the Brancott Winery.

I think this was my 10^th time on the tour, but in any case, it's always interesting to go, as you learn new things every time, and it's also fascinating to see how the wine business changes from year to year to year.

We were given a very good talk about the future by Dr Michael Trought of the Marlborough Wine Research Centre, who mentioned new harvesting technology that is being developed as I type.

This was in the news a little while ago and has created a bit of a stir. It isn't actually all that new an idea, as this article from 2008 can confirm, but it is, as far as I'm aware, the first time the technology has actually been seen working in New Zealand.

On what is a fairly ordinary machine harvester, built by ERO, is added the innovation of on-board grape processing.

Not only does the machine harvest the grapes, but it also crushes and extracts the juice out of them them (using a centrifuge), so that instead of a mix of grape skins, seeds, pulp and material other than grape (e.g. leaves, petioles and other things that get collected by the harvester) being discharged into a bin being towed in an adjacent row, clear grape juice comes out. The grape skins and seeds are discharged to the ground in the vineyard.

As Dr Trought demonstrated to us, the juice coming out of this machine was very clear, having only a small amount of solids suspended in it (after juice is pressed from the grapes, it is normally put into a tank and allowed time for the bits of grape that came out with it to settle to the bottom of the tank - the clear juice off the top is then the premium stuff). This is desirable because there is less loss of good juice during the settling process, which probably makes up for the slightly lower litres of juice recovered per tonne of grapes that the machine juicer gets compared to the conventional press.

So what this technology can deliver is pretty clear juice straight from the vineyard.

What does this mean? Well, it means that about 20% of the weight of the fruit (skins and seeds) doesn't have to be carted to the winery, only to have to be carted back out again. There's a savings here in the number of trucks/drivers/amount of fuel needed to move the grapes to the winery and then the grape solids back to a composting facility.

It means that for those varieties that can be harvested in this way, a press is not needed back at the winery. This leads to lower capital expenditure to establish a winery.

It means that fewer people will be needed to process the grapes. A plus for the winery, but not so good for those wanting to work in wineries!

Potentially it could mean that lesser amounts of processing aids are needed to recover top-quality clear juice, leading to cost savings and more efficient use of tank space.

There are disadvantages, though. Grape waste, which is normally collected from the winery and distributed back into the vineyards, cattle yards or the composting facility, are now returned in raw form to the vineyard floor. Grape skins and seed waste has a high carbon to nitrogen ratio (C:N) of about 27:1 (Ferrer et al.2001), so leaving it out in the vineyard as it is can result in a loss of root-available nitrogen to the vines. That's not to mention that it's a bit of a slippery mess!

As well, it's pretty much useless for red wine, as the colour and mouth feel properties of the wine are tied up in the seeds and skins. If you juice the grapes in the vineyard, there is no chance for these things to be extracted into the wine.

And, as well, many white wines are made using a bit of skin contact time. That is, after the grapes are crushed, the skins are left to stew in the juice for a while. This allows flavour and aroma compounds to be extracted, as well as tannins and other compounds from the skin that can have an effect on the way the wine smells and tastes. This isn't feasible with the current machine.

A significant point for New Zealand when considering this technology is that the country's most famous wine, the Marlborough-style Sauvignon blanc, actually relies on some post-crushing skin contact time to lend it some of the aroma characteristics that it's so well known for.

It's highly likely that this time and effort-saving machine may not be able to be used with the grape that makes up almost 50% of the grape area planted.

Bummer!

Biodynamics - a viticulturist's view

We have a V&O student forum at Lincoln University, where posts about tastings, announcements, and other tidbits can be seen by all. One student just put up a, shall we say, "incite"-ful post about Biodynamics. That is to say, they were attempting to stir the pot...


I thought I would put in my two cents worth, from my view as a viticulturist, so I've repeated it here:

My experiences with Biodynamics goes back to when I first visited James Millton up in Gisborne more than 10 years ago. He makes fantastic wines, and in one of the more difficult places to grow grapes in NZ due to the increased disease pressure there.

Some of my research dealt with maximising vines' natural resistance to fungal diseases through phytoalexins, so he invited me up there to have a chat and see what they were doing.

As a viticulturist, I came away from it not really wondering what the effects of the Biodynamic preparations were, but rather being impressed with the amount of attention paid to the soil, the vines and the grapes.

Growing organically or Biodynamically means that the viticulturist has to be much more "in tune" with the grapes and the environment. In order to manage diseases, and since they don't have fungicides as effective as synthetic ones, they need to be much more aware of what the canopies are like, and manage them more actively. This means they are out looking at the vines more often and putting into effect management decisions in a timely fashion: staying ahead of the problems.

So my take on this topic is that it isn't necessarily the preparations or ethos of Biodynamics and the Steiner principles that are at work, but rather viticulturists that are much more aware of what is going on in their vineyards, and anticipating problems rather than reacting to them.

Anything that gets people into their vineyards more and looking critically and thoughtfully about their vines has got to be better for the health of the vineyard and the quality of the grapes, regardless if it comes about through a belief in anthroposophism, the principles of organic farming, or an obsessive-compulsive disorder relating to lianas...  :-)

Climate change and eco-mindedness

TizWine recently sent out a link to an article about climate change in California and its effects on the wine industry (Napa Valley Register).

It's not really focused on climate change in terms of  global warming, but more the climate of perception and ideas about vineyard management.

There is beginning to be more emphasis on looking at more than just dollars in the bottom line. The article describes how some parts of vineyards that were prone to flooding were ripped out to improve flow through it for wet times of the year. Native plants are being planted near vineyards to encourage native fauna (much like the Greening Waipara programme here in Canterbury) and increase biodiversity.

Then, the use of solar panels to generate electricity, the excess of which can be fed back into the grid (There are reasonably good rebate programmes in the States that assist companies to put in alternative energy generations - would that New Zealand had a similar stance), is described - these are sitting on the surface of a pond, which can have multiple benefits in that it would also reduce evaporation from the pond's surface.

Napa is cooler than one might expect from its latitude, primarily because fogs roll in off the ocean during the night, and don't burn off until later in the day. The change in climate will affect this, and I think it would be rather sensitive, too. If the fogs burned off a couple of hours earlier each day, there could be significant effects on the number of heat units gained in those areas. Likewise, if the fogs hang around for longer, things could be a bit cooler. On reflection, that could be a good thing - maybe the alcohol levels in the wines won't get so high! :-)

So to combat this, they're changing the orientation of the vine rows (typically they run north-south, so there is sun on the east side in the morning and on the west side in the afternoon) to more northwest-southeast, so that in the hotter parts of the day the sun-side of the vines don't get the full brunt of the light and heat.

As well, more leaf cover also can reduce fruit temperature and minimise the amount of berry burn:

In this picture, the leaves were removed over a shaded cluster and shoot, and the resulting exposure to the sun has done considerable damage to parts of the berries but also the shoot and rachis!

So keeping some leaves on to get dappled light on the clusters can be a good thing if you are growing in a hot area. Trellising choice also has an influence, as those systems where the fruit is below the canopy (e.g. pergola (overhead) or T-trellis)are better off in those conditions.

 A Parronal vineyard in Chile. Also called a pergola or overhead trellis system. Here shoots have recently been thinned from the vines to create a more dappled light effect on the grapes and ground beneath.

A T-trellis system in Australia. Here the grapes hang beneath the canopy, too, but there doesn't need to be an elaborate overhead wire system to support the vines.

Trellis systems like there are more commonly used for table grapes, where the appearance of the fruit is especially important.

There is no doubt in my mind that we will need to alter management of our vines to suit changes in climate over the next 40 years - as with all things viticulture, planning for it beforehand is the best approach. So read through the climate projections for your area, and make a plan to deal with the possible changes - before they happen and its too late!!!

Thoughts on thinning - how much does a cluster contribute to yield?

It's such an early season in Canterbury this year!

Just before the nets went on in the Lincoln University Vineyard (the earliest they've gone on in the 13 years I've been here!), we were able to squeeze in some fruit thinning. That prompted me to write the following for the Wines of Canterbury newsletter...

Despite all the heat and promise of a fantastic season, why go through all that trouble when it looks like it will be a year where you can leave all that crop on and get it ripe?

Well, the first thing to check is how much crop you've got! We looked at the Pinot noir and Pinot gris and found that cluster counts were around 20 per metre of row for both of them. Not only that, but the clusters looked pretty big, too, so some more investigation suggested that berry number per cluster was around 125. So figure about 1.1 grams per berry for the productive clones of Pinot noir, and more than that for the Pinot gris, and you're looking at crop loads of around 2.7 or more kilograms per meter of row. Too much!!

For the mythical balanced VSP vineyard (refer to Sunlight into Wine, by Smart and Robinson, 1992), a typical pruning weight per metre of row should be about 0.5kg. Using a yield to pruning weight ratio of about 3 (which, while less than the 5 to 10 figure used by Smart and Robinson, seems to be more appropriate for vines in the Canterbury region) each meter of row should be able to (nicely) ripen 3 multiplied by 0.5kg of fruit, or 1.5kg.

So by doing some quick cluster and berry counts, we can see that there is quite a bit of extra crop on there, to the tune of at least a kilogram per metre of row!

So we need to take off about 44% of the fruit that's on the vine, which could be thought of as slightly fewer than every other cluster.

However, it's important to note that not all clusters are the same. The basal cluster is usually the most advanced in terms of ripening, so it's beneficial to keep as many of those as possible. But if you're removing all the upper clusters, it's important to note that they are also usually smaller, to the tune of about 70%, than the basal clusters. So if a basal cluster is 100g, the cluster above it will be about 70g, and if there's a third cluster on there (which the Chardonnay clone UCD6, for example, has in spades this season), it will be about 50g (it might be a good idea at harvest to do some measurements of this in your vineyard and with your varieties to see if this holds true in your situation).

So if you remove just the top cluster, you're looking at a reduction in yield by about 23% - not a third if you think of the clusters as being all equal. If you remove all but the basal cluster, you've taken off about 54% of the fruit. So to reach the goal of taking off 44% of the fruit, you should be removing all the top clusters, plus most of the secondary clusters.

Whether or not this is an economically feasible thing to do is another matter!!

Unwanted rootstock growth

There are lots of good reasons to use rootstock-grafted vines aside from their ability to grow in phylloxera-infested soils. We have rootstocks for dry areas, salty soils, high pH soils, nematode-infested soils etc.

However, grafted vines do cost more than own root vines, and for good reason - there is a lot of hand work that goes into producing each one. One of the important steps is the disbudding of the rootstock before the scion is grafted to it. If the buds are not removed, the rootstock can grow underneath the scion, and has the potential to drain some of the rootstock's reserves away from the scion, or in some cases, result in the withering away of the scion.

So one thing a viticulturist hates to see (or that I hate to see, anyway!) is something like this in the vineyard:

Here is 101-14 rootstock growing out from below ground on a Pinot noir vine. This is a case where the disbudding, which is done by a machine these days, went wrong, and a growing point was left on the rootstock of the grafted vine.

It can be difficult to spot if the machine has done a good job of removing he buds, but there's another chance to catch an error like this while the vine is in the nursery, growing the season after the graft is made.

Obviously, however, some of these devils get through and make it in to the commercial plantings.

What to do? Well, I certainly don't want them in the vineyard, so it was time to get down on my hands and knees and get rid of them. It's not as simple as pulling up the shoot, as if you do this there will invariably be some part of the shoot left, or some embedded buds will be left behind. So let the digging commence!

You need to cut the base of the shoot right out, much like you need to cut a node out on a trunk if you don't want to see any shoots arising from there later in the vine's life.

Therefore, you need to dig down to the base of the offending rootstock shoot, and use a pair of secateurs or similar to cut the shoot out, taking some of the bark and wood out from around its base. This should remove any basal buds that will be hiding in the shoot.

This picture shows where the rootstock shoot joined a vine - I used the secateurs to cut out a portion of the trunk around the base of the shoot. I leave the hole open for a day or two so that the wound can heal up in the dry and hopefully prevent any nasty soil organisms from working their way in there. Then the soil can be pushed back in.

If the job has been done right, and all the buds have been removed - no more rootstock growth. If it hasn't been successful, you'll have to do the job all over again!!

I hate digging in the soil around the vines, so I do my best to get it done right the first time!!!

Google Refine -a way to clean up and transform your data

I came across the online tool Google Refine the other day.

This is something like the search and replace function for data, only more powerful, and incorporating online resources.

Google acquired the technology from Freebase and its Gridworks software.

The tool allows you to manipulate data in both simple and sophisticated ways. Simple as in finding and replacing text and the like. Simple as in finding closely related entries in a spreadsheet and combining them with a few clicks of the mouse. Handy in finding typos in database entries and correcting them (I like this feature a lot!!).

More complex manipulations would be like taking information in a spreadsheet cell and using that to call up related information from the web, which can be added to the spreadsheet as additional columns. E.g., you could have a list of cities, and potentially query the web to get monthly temperature and rainfall data for each of them, without having to go through them all individually.

Mind you, this requires having the information available, and also it will require a bit of learning of the syntax required by the software to do the more complex manipulations, but on the other hand, it's a big step up from the functions available in the typical spreadsheet!