Wine Growing, Weather Spotting
Stephen Doyle
Whether the weather is cold
Whether the weather is cold
Or whether the weather is hot
Whether the weather is wet
Or whether the weather is not
We'll weather the weather, whatever the weather
Whether we like it or not. Discuss:
A Metaphor For Our Times: Bloodwood Cows nonchalantly graze below the Schubert oblivious to an approaching bushfire.
Observations from the relative cold face of Australian wine growing
Well before I get into the above below, so to speak, I should say something about climate change in the Australian viticultural context. We've kept detailed weather records and observations since 1983 for Bloodwood and with this (very site specific) data behind us there are a few comments we can advance in the context of this industry locally. In Australia, there are many great advantages in growing quality wine grapes at our latitude in such an elevated region, remote from the coast. At over 800 metres our meso-climate guarantees relative coolness regardless of the current seasonal variations and importantly this includes reliable diurnal variation.
Orange has long been a great place to grow a wide selection of high quality temperate fruits including apples, pears, nectarines and zippy cherries. Quality pome and stone fruits require cool nights and warmish days during their autumn ripening period to promote flavour, preserve the natural acid brightness and deeply colour the skin. So it is with quality cool climate wine grapes. Over the last three decades, while we can report that day temperatures are showing a gradual upward trend, because of our elevation, the dry, cloudless nights have remained relatively crisp. Rainfall analysis does not show any statistical decline with the last 12 difficult years recording a yearly average of 830 mm. The median rainfall for the same period is 880 mm, so the variability of rainfall does seem to be increasing. (See Monthly Rainfall Jan 1998 to Dec 2009)
From the illustrations below of droughts and flooding rains, this is plainly evident. What does seem to be changing though, is that average bud burst dates in the vineyard with the early varieties like Chardonnay and Pinot Noir advancing. These have gradually moved forward around a week or so, however, late season reds like Shiraz and Cabernet Sauvignon have remained steady. (In 1982, my thesis on this area predicted the first week in October as bud burst for Cabernet Sauvignon, and this doesn't seem to have altered to date ) As a consequence, vintage recently has been a far more relaxed affair with an early season rush of some whites like Chardonnay around mid-March, followed by a pause while the reds catch up, ripening well into April. We'd like to be able to record evapotranspiration changes here at Bloodwood, as we suspect that although the rainfall has been statistically relatively stable, it's seasonal effectiveness has not been maintained.
So in summary, our view is that while the recent climatic averages have not shown significant change at Bloodwood, the fluctuations around these figures have increased. The climate seems to be stretching at the seams. This poses additional problems for every wine growing area in Australia, although from the following bare statistics compiled from Bureau of Meteorology figures, in Australian terms at least, Orange is a very fortunate place to grow good quality cool climate wine grapes.( Bloodwood Meteorological Matrix Summer 2009/10.)
However, no matter how good the quality, someone still has to be willing to buy the fine wines they undoubtedly produce here at Bloodwood. That's where you lot come in!
The Story so far
Being a wine grower, or indeed any breed of agriculturalist, means, whether you like it or not, you have an intimate relationship with weather. And the fact is, almost every day on your vineyard, you will be presented with questions posed by the prevailing weather conditions. Often these questions, because of their sometimes confronting nature require immediate response. It's out with the chain saw and your trusty fungicide sprayer almost as soon as the immediate danger passes. Other inquiries grind up on you over a season or a couple of years. How will the lack of rain this winter or the extraordinarily cool summer predicted effect the bud differentiation in the vintage after this one? Will the unseasonal early vintage rainfall ruin any prospect for quality with the late season reds? How can global climate change really leave your spec on the communal crust we call the Earth, un-noticed? And, logically, can we do anything about it all in the end?.
Well, even though I have occasionally overheard mutterings through gritted teeth that the only difference between God and a winemaker is that God doesn't think he is a winemaker, here are a few weather challenges we've, ahem, recently experienced at Bloodwood, along with the odd tip or two on how to negotiate a truce with the weather gods concerned.
Flood in drought at Bloodwood
Rain on a parched landscape should surely not be a problem. Well, it all depends on how violently it arrives and how much vegetative ground cover you have retained in your vineyard. You see, to be effective the rainfall needs to be held in the vineyard and percolate through the top 30 cms or so of the soil surface so the vine roots can take advantage of welcome moisture. Often. by mid-summer, with all the pressure of spray carts and tractor movements up and down each row compacting the soil, a sudden rainfall simply runs over the vineyard surface and out through the surrounding parched catchment. This is a shame, as, in our part of the world, summer rain is often nitrogen-rich thunderstorm rain during a period in which the vineyard is looking for a drink. That is why, at Bloodwood we maintain a permanent sward in the vineyard and mulch all winter prunings and organic summer re-growth grasses through the side delivery slashers on to our vine rows. Then, if it does rain, there is an improved chance it will be beneficial to our vines.
Dust storm in Winter
Well the place is called BLOODwood after all! Over the best part of the last three decades, we've experienced a dozen or more dust storms. Usually they occur in late summer or early autumn as the vigorous weather patterns of summer grudgingly give way to the more settled outlook of autumn. With the recent malingering drought conditions across Australia they seem to be becoming less uncommon. While a winter event like the one above is a nuisance, vintage time storms are more problematic. Now while the term "dusty" is sometimes used when describing Bloodwood Cabernet Sauvignon, I don't think this is quite what our esteemed critics mean. But it does make us think twice about our imprecise appreciation of "terrior" here at Bloodwood, and all that iron-laden dust on vigourously respiring leaves during the growing season leaves us wondering.
Flood rain in late Spring
Sufficient rainfall through late winter and spring is critical for our vines. While we do have drip irrigation to each and every one of our 21,274 vines at Bloodwood, we only collect water through hill-side dams like the one above. Given we are at the very top of the Broken Shaft Creek catchment, all the water used in our vineyard must be harvested from the slopes surrounding each vineyard and parsimoniously reticulated as needed during critical phases of the vine's growth. Since we started the vineyard here in 1983, the average water use has been slightly less than 0.8 megalitres per hectare, per year. In some years, like 2007 we don't have to irrigate at all during the growing season whereas vintage 2004 was quite the opposite. Such is the variability of Australian growing conditions. Note the absurdist wharf fixed to the wall of the pump shed. This is an existential environmental statement on our part in that it says so much about surviving this challenging Australian environment. The only time the wharf lives up to its name is when the dam is full, and that's the only time, because there is no access door from the pump shed, that we can't access the wharf. Or it could be a stuff up on the part of whomever built the thing.
Severe late autumn drought
The driest three months at Bloodwood are February, March and April. From a wine making perspective, this is a good thing. It means that, given we are operating in a relatively cool climate, we can leave our fruit to hang while gently ripening in the cool autumn air. Importantly though, quality grapes need a little timely moisture to encourage the process, so it is important that we keep the canopy on the vines throughout the ripening phase and for as long as possible after vintage. This allows the vine to gather as much of its remaining summer energy into its structure so it can survive winter and importantly, make a good start to the next growing season. As a result, we often find ourselves giving our vines a good irrigation after harvest while the canopy is still functioning and before the first late May frosts drop the leaves to the vineyard floor. Traditionally, the first signs of an autumnal break usually arrive with a rain event in late March, followed by softer and cooler conditions into April and May. If it hasn't rained by early May, we know we are in for a very tough winter ahead.
Close Encounters of The Third Kind
So you've survived the physical drag of winter hand pruning, repaired your trellis wires and gotten the spring grasses under control. You've even managed, against the odds, to apply at the appropriate time the appropriate number of Copper and Sulfur sprays to head off seasonal fungal outbreaks of downy and powdery mildew. Not only that, the weather god's dispositions have been sunny and calm enough to allow your Chardonnay and Pinot Noir vines to set a modest crop for the coming vintage. Your Cabernet Franc, Riesling and Malbec are at mid-flower and the Shiraz and Cabernet Sauvignon inflorescences are plump with promise. For once, spring rains have been gentle and reliable, and the frost danger has well and truly past with Melbourne Cup day. You've also won a Highly Recommended citation for your botrytis Nebbiolo at the Galargenbone District Biodynamic Advancement Exhibition, and all is right with your world. So what can go wrong. Was it Auden who wrote that in this happy contented picnic we all call life, death is the rumble of an inevitable approaching thunderstorm?. Well, we get our share of them at Bloodwood and when they arrive, there is nowhere to hide. All Grape Growing 101 courses should include a compulsory lecture entitled pre-traumatic stress management; because if you have the hubris to grow grapes in Australia, you're going to need to pay close attention to what makes you and the weather gods tick.
A Chainsaw is sometimes needed to visit Bloodwood
Our American cousins call them twisters, our smaller versions we call willy-willys. If your vineyard is in the path of one of them, the localised damage can be severe. Every few years, we need a chainsaw to get down to the Mitchell Highway from Bloodwood. Mature trees are snapped off mid-trunk and a swathe is cut across the landscape. It is frightening to experience but thankfully not a common occurrence. To recycle advice previous, when you see one approach it is time to duck and cover.
Winds can strip tender, young Spring shoots
Spring is about the most changeable time in the Bloodwood vineyard and winds get a kick along from the East when big South Pacific High pressure systems park themselves across the Tasman during this time of year. The conventional wisdom in the Orange area is that SW winds are the most damaging to our vineyards, particularly when they are very cold and fresh; however in a protected vineyard like ours, with exposures to the North and East while sheltered to the West and South West, the ESE gale during the early growing season causes us the most angst.
When drought grips the land
We're not too sure how useful a drought is. The annual dry is a feature of this, the driest occupied continent on the planet. In fact, provided the rainfall eases off leading up to and through vintage, in our game that is a good thing. The Orange area is unique in the cooler end of Australian viticulture in that excessive vintage rainfall is relatively rare. Unlike our coastal cool climate wine growing areas, Orange is far enough inland to be practically out of reach of the damaging East Coast low pressure systems. While it is a fact of life in the warm vineyards of the Hunter Valley that these depressions can cause much vintage time heart break earlier in the year, even cooler sites closer to the coast throughout South eastern Australia are prone to April and May incarnations of this weather system. The 280 kilometres between Bloodwood and Bondi which incorporates the barrier of the Blue Mountains means that most all we get on the western side of Orange is the puff without the precipitation. Most of our seasonal rain comes via southern ocean fronts releasing their moisture on the slopes of Mount Canobolas after crossing the flat lands between us and the Mt Lofty ranges in South Australia. When these rains fail, it doesn't take long for the paddocks to petrify and the atmosphere to ache.
Early Summer hail storm
The last gasps of winter fronts in spring often bring very gusty Antarctic winds and sleet with them. If this occurs after bud burst, then tissue damage is sure to follow. Unless the hail is massive, this is a problem we just have to live with in such a cool, elevated area as Bloodwood. If we can manage to get a protective fungicide applied as soon as possible after the damage and the vines quickly dry out, then the serrations and battering they have endured will be quickly grown through. If the weather remains stubbornly sleety and gusty, then the seeds of an eventual botrytis outbreak are sown. Hail storms are more of a potential problem later in the season after fruit set. Over the years we've noticed that the damage caused by moderate storms is more pronounced between berry set (when the fruit is hard and green) and veraison when the berries begin to soften. It may have something to do with the hardening of the foliage as it matures and the turgid fruit post-veraison acting as a pneumatic buffer against the hail. If we experience damage like that shown below, our usual procedure is to spray the vineyard with a PMS solution of around 1000 ppm to help dry out and sterilize the split berries followed by a careful fungicide and foliar nutrition programme aimed at helping the vines over the immediate stress. We then carefully apply a bottle or two of Bloodwood Chardonnay to all witnesses present and pray for continuing sunshine.
Berries split after early summer hail
Rainfall at vintage
If you want to know what the weather will be like tomorrow, there's a better than even bet that it will be similar to what it is today. We're talking more suspicion than science here, however experience tells us that there may be some truth in that observation. The picture above is the Schubert vineyard in late summer 2007. Even a casual observer can see that the vines are wet..they also look to be various tones of green through to brown. The lighter leaves and shoots towards the tips of the canopy are new young growth while the rusty foliage is older, sadder tissue. In growing season 2007, the rains came in January and really didn't leave off until late July. While the vintage period itself was briefly dry, there was enough unseasonable moisture about after a very dry Spring and early Summer to really confuse vines' growing pattern and promote late season fungal disease. We generally use soft, elemental fungicides like Copper and Sulfur for control of downy and powdery mildews at Bloodwood and these require regular application because they are not rain fast during wet weather. If disease develops and the weather remains un-cooperative, then it becomes very difficult to control. You will not be surprised that there will be no Schubert released from the 2007 vintage at Bloodwood.
Half a degree can make all the difference on a frosty morning. The coldest time during a calm radiation frost is just as the sun peaks its head over the dawn horizon. Tender young inflorescences like the one above are more prone than the surrounding tissue in a marginal frost event. The more mature foliage and the slightly tougher shoots have basically survived with passing damage, while the young tender flower cluster has been burnt off. This is one of the cruelest cuts of all in the vineyard. The vines look fine..it's just that they will produce only foliage for this vintage. That's why it is important in marginal areas like Orange that you give your vines every chance by ensuring that the sward beneath the vines is kept clipped low, and that you make sure that there are no impediments (farm sheds; paddock dams; tree lines and so on) to the free flow away of cold dawn air. For a few site selection frost hints, please keep reading below.
Severe mid-winter frost
In the time we have been growing grapes at Bloodwood we have never experienced a growing season frost of any consequence. When the vines are first planted, if your weed control is not perfect, there is every likelihood that early bursting varieties like Chardonnay will cop a burn off on the ground. This,we've noticed, makes them mad for a while before they really get a spurt on as the season warms up. Before we decided to plant vines on Bloodwood, we were warned that they would be frosted out as a matter of course, and what we were doing was folly in the extreme. As a consequence we were very aware of the theoretical potential for frost damage and one of the main criteria for selecting our site was its relative freedom from frost damage during the growing season. This involved finding a site which had good air drainage against localized radiation frost events as well as enough protection from the cold SW freeze frost mass air movement events which are too common in the southern Australian vineyard. We also took the precaution of installing a trellis with a cordon height of 1.1 metres and end posts which were at least 2.4 metres out of the ground. This, and the warmer than usual free draining gravels of our slopes helped trap early season warmth and lessen the dangers of any potential frost event.
We do, however, cop our share of severe winter frosts like the one pictured above. These are generally thought to be a good thing for the health of the vineyard. As the climate warms up, proper vine dormancy in cool climate maritime vineyards is going to become a greater concern. Uneven dormancy leads to dispirited bud burst, and patchy ripening..not a good thing for quality wines. Vines respond well to uniform cold during this time of the year. Provided the temperature doesn't get down beyond around -12C for any length of time, they won't die while their resident populations of fungi and spores will not enjoy such a solid cold snap. The overall hygiene of the vineyard will improve.
Now here's a Bloodwood special site selection tip to avoid frost problems in cool climate vineyards in elevated areas like Orange. Stand in the middle of your proposed site, fold your arms, lift your head up to the horizon and rotate yourself through 360 degrees. If there is more than half of your horizon blocked by surrounding hills, find another site.
Late Winter snow stor
Snow falls at Bloodwood are not an unusual winter event. We normally see four or five occasions where snow rides silently in on overnight winter fronts from the South-West. The big dry flakes swirl around the winery and vineyard accumulating into a brilliantly white acoustic blanket which first hushes and then slushes every visible surface. Snow falls give us reason to pause for a day and enjoy their arrival, a time to sit, and listen to the silken silence while we can before it melts away into the landscape. We don't know if they are beneficial to the vineyard, but they surely restore us.
Anyone for tennis?