Things really are starting to get to the pointy end of the growing season here in the Adelaide Hills.
Some earlier ripening grape varieties are already starting to show the first signs of veraison (EL-34)! And the rest aren’t too far behind.
This is a photo of tempranillo at Macclesfield from the lastest CropWatch report…
For those of your scratching your head wondering what on earth veraison is, here’s a quick catch-up for you…
Veraison (pronounced verr-ray-zon) is very much the turning point in a vine’s annual lifecycle. At this stage, the vine changes its focus from energy creation (via photosynthesis) to energy consumption.
Veraison is specifically defined as the stage at which three simultaneous but separate processes begin…
1. Each berry softens as the cells within the grapes begin to produce more juice and the skin becomes thinner.
2. Sugar starts to accumulate and acidity of the grape starts dropping away.
3. Colour starts to change – from green to red in red varieties and from green to translucent in white varieties.
Before veraison begins, the berries are still very small, hard, acidic and green (due to the presence of chlorophyll). At E-L stage 35, the vine starts to move its energy stores from the roots and leaves into the berries. The chlorophyll is converted to anthocyanins (in red varieties) or carotenoids (in white varieties), sugars and other compounds, many of which are the precursors to the flavours and aromas which we can taste in the resulting wine.
Following the onset of veraison, the ripening process then takes anywhere from 30–70 days for the grapes to become fully ready to make wine. The grapes still have a lot of growing up to do during that time. In fact, each berry will double in size between now and when they are picked.
If you live in the Hills or just keep a close eye on the weather around the country, you’ll know we’ve had some interesting weather of late.
Back on the 22nd of January, the Adelaide Hills Wine Region (AHWR) recorded falls of up to 49.9mm at Balhannah. And then came the humidity. Uuuurrghh. My hair did not like that one bit!
But let’s forget about my hair for a minute, what does that mean for the grapes and will it have any detrimental effects on this vintage?
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The thing that worries growers the most about rain is the potential for disease. If you need a quick reminder of the types of diseases (and pests) they’re worried about, check out this post from last year.
On Australia Day, CropWatch issued a downy mildew monitoring alert.
This just means that the high rainfall and warm temperatures put all vineyards in the region at risk of primary and secondary downy mildew infections.
There is some great news though…
At this point in the growing season there is minimal risk to grape berries. That’s becasue, by now they have developed resistance to downy mildew infection. Leaves that have been around for a while have also developed resistance.
Just quickly… once grapes have reached E-L 29 (berries peppercorn size, bunches tending downwards) any new downy mildew spores that land on the vines do not seem to establish themselves. I’m sre there is a really great reason for this and I promise to look further into it one day!
However, younger leaves and fresh growth are still vulnerable to downy mildew infection.
Vineyard managers have been aware of the risk of downy mildew infection as the season has been challenging for downy mildew (and Botrytis). Most vineyards have applied spray programs that would provide good control in a normal season. The problem is though, the weather conditions throughout this season have been tough. They include rain, wind and difficulties with vineyard access early in the season due to a wet winter.
Powdery mildew symptoms have begun to develop across the region. Overcast conditions and shaded canopies have been challenging even the most up-to-date fungicide spray programs.
The issue with developing powdery mildew this late in the season is that window for applying fungicides is closing.
You see, growers have to adhere to some pretty strict rules when it comes to the timing of their fungicide applications.
Particular fungicides can not be applied within a specific number of days prior to harvest (between zero and up to 63 days).
Vineyard managers rely on a guide called the AWRI Dog Book (not even joking) which outlines all the timings for all of the different chemicals used in vineyards.
And why is it called the “Dog Book”? Because of this cute little customs beagle on the front…!
Botrytis infections are enhanced by the presence of sugars in berries and by wounds caused by split berries. Berries split for a number of reasons including bucket loads of rain and advanced powdery mildew infections.
Fortunately, our recent rain hit prior to veraison. This means sugar levels had not developed to the level where berries split. However, where berries are damaged (for other reasons) infections have been able to establish.
So, the sooner those berries ripen up and get themselves ready to pick the better!
Here’s hoping the rest of the season is uneventful!
Chardonnay is back!
Literally as you are reading this, our 2021 Chardonnay is heading down the bottling line! It will be a matter of days before it’s back on the list and ready for your glass!