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!!

Shoot thinning - The importance of keeping your head clear

Note -this post is based on an article I wrote for the Wines of Canterbury newsletter this month...

Spring is all around us in Canterbury, and the grapevines have responded by shooting away madly. From trying to keep pace with the grass growth (trying to keep it as short as possible), now that the frost season is (hopefully) dying away, my attentions have turned to canopy management.

On the ideal, balanced, vine we get even bud break and shoot development and one shoot arising per node left at pruning. While we all strive for the ideal vine, it is something that rarely occurs, so we are left dealing with reality - in the case of my five year old Pinot noir vines, reality means that I occasionally get more than one shoot per node left, and there are a considerable number of extra (non-count) shoots coming from the head region.

Because I have only a backpack airblast sprayer for my own vineyard, the air turbulence it makes isn't all that good, and therefore neither is spray coverage. I need an open canopy to make the most of what the blower can deliver. So this means I can't tolerate all the extra, non-count shoots that have popped up on the vines.

The ideal shoot density for a VSP-type system is around 15 shoots per metre of row, or about 6-7cm between shoots. On cane pruned vines, the internode length of the cane laid down during pruning determined the spacing of the nodes and therefore the expected shoots in spring. So if you have used canes with a shorter internode than this, you will have a potential problem. For me, 18 shoots per metre of row (about 5.5cm between shoots) is okay, but every time you increase the number of shoots per length of row, you're increasing the risk of poor fruit exposure and lesser air movement - neither of which is desirable. And this is not even considering the possibility of extra shoots coming up from nodes or from the older wood around the head.

So I went through a did shoot thinning the last couple of weekends. The general rule is, retain only one shoot per node left at pruning, and if you're taking one off, remove the one with less crop. However, there are times when I left the second shoot on. This happened when there was a blind node next to the node with two shoots - in that case, I would often leave the two shoots, so as to make sure the canopy was continuous and to keep the average shoot number per metre near its target.

Other times, the internodes were shorter than ideal on the cane that I laid down, so then I might remove a shoot from a node position to make way for the neighbouring shoots (see Figure 1).

Figure 1. Compressed internode leading to two closely spaced shoots. I took off the ones (there is a secondary, non-count, shoot pointing toward the camera) on the centre-right to open things up a bit

 

 

 

In yet other cases, shoots would be growing out from the lower side of a cane and shooting sideways rather than up (see Figure 2). I will remove these, too, if they are going to grow to the side and therefore put a lot of leaf in the fruiting zone.

Figure 2. A sneaky sideways slithering shoot. Definitely up to no good!!

Around the head of the vine things get a bit trickier. A mantra of mine is that thoughts about pruning carry on through the rest of the season. If there is a non-count shoot that could be of use when it comes to pruning later in 2012, then I take pains to preserve it! For instance, I have a couple of vines where the canes laid down originate very close to the fruiting wire, but no growth is available below it to leave as a spur. Therefore, if I get any kind of growth below the wire, I hope to save that in the hope that it might become a decent spur to leave at pruning, or better yet, leave as a cane.

This means I take a bit of extra time to ensure I don't remove something potentially important, but then when it comes to pruning next year, it will make the job easier and therefore faster.

The before and after pictures of shoot thinning can be quite enlightening (Figure 3)! There should be quite a bit of space between shoots at this time of year, which is good for the development of flower clusters for the 2013 vintage (they will be initiated in the month of December, so good light exposure now should mean good light exposure until flowering) and good for airflow.

Figure 3. Before and after pictures of shoot thinning around the head region on a 12 year old Pinot noir vine. Note that no shoots have been left at the top of the head - this is because it's very close to the fruiting wire, so shoots arising from there wouldn't be able to be used effectively at pruning. As well, opening up the head area leaves space for the shoots coming up from below the wire.

The reason why I do this thinning now is that it's a lot easier to see all the shoots, and a lot easier to take them off (especially without damaging neighbouring shoots), but also because I want to ensure I get good spray coverage - some areas around the heads are very densely packed with shoots.

On my ultra-premium vineyard, labour is something that I try not to skimp on. After all, when an academic plants a vineyard, it's bound to be under a lot of scrutiny!!

Messy looking vineyards

While travelling around vineyards in the Niagara Peninsula and also Upstate New York, one of the things that could strike a person used to New Zealand vineyards is that the vineyards are all pretty untidy.

The contrast is that in New Zealand, virtually all the vineyards are two or four-cane vines on vertical shoot positioned (VSP) trellises. the fruit is concentrated near the bottom of the canopy on the vine, and the shoots are all supposed to be trained up. Aside from this, the sides and tops of the canopy are trimmed mechanically to give the vines a nice, neat hedge-like appearance.


Where we are now, the majority of the vineyards are VSP, but there are still lots of shoots going everywhere, up, sideways, down, over etc.

I maintain that one of the reasons that VSP is such a popular trellising system is that it can result in a very neat looking vineyard, which appeals to people's eyes. After all, most of us would take the time to make sure the plants in our gardens look tidy, trimmed and well looked after. What will people think about the state of a vineyard if it isn't in the same kind of shape? (I will have to write later about the pros and cons of a tidy-looking vineyard versus an unkept one! :-)

So what reasons can I come up with for the difference in vineyard appearance between NZ and here?

Well, one reason is the amount of rain that's fallen here this season. By all accounts, it has been a wet year, with much more rain than usual. This means the vines have access to a lot of water, which encourages vegetative growth. So at this time of season, when the grapes are starting to colour up and get into the ripening phase, we would normally expect that the grass between the rows has browned off, and the vine shoots to have stopped growing due to the lack of water.

So because the vines are growing a lot more, it means that to maintain the neat and tidy appearance of all the rows requires more work, for the same end result (this being the quality of the grapes being harvested). If there aren't enough resources (and with the economic downturn, this is a hard reality for a lot of businesses!) to go through and do all the necessary shoot positioning, lateral removal, leaf pulling and trimming, the vines start to look a bit hairy.

So this is one possible reason for the vines not looking like they do in all the coffee-table wine books laying around!

So would NZ vineyards look like this if there was above-average rainfall? Yes, they would. However, this is less likely, as most of the vineyards in New Zealand do not get enough rainfall to support vines through the year, so they have irrigation systems put in, to deliver supplemental water. So even if we have above average rainfall, it may not mean that the vines have luxury amounts of water available to them, and therefore the vegetative response is not the same as it is around here.