jamie goode's wine blog: Greenness in South African reds

Friday, February 03, 2006

Greenness in South African reds

Some thoughts on greenness in South African reds, prompted by comments on an earlier post. First, let me state that I'm a big fan of South African wines. I've been there twice in the last couple of years, most recently in December 2005, and I was excited by a lot of what I tasted. But at the same time, I have to say that a proportion of the red wines suffer from a green streak, which I assume is caused by a proportion of unripe grapes.

What's the cause of this? South Africa shouldn't have problems with ripeness; its premium wine regions are pretty warm. Many commentators lay the blame at the door of leaf roll virus infections, which are a huge problem in many areas of the Western Cape. You can read about this here (I'm linking to Google's cache of the article; the Wine Spectator now charges for access), and there's a wonderful, but more technical article on the problem here.

At one property I visited in December they replanted five years ago, and are now having to replant again, because the new planting material is already virus infected. The big problem is that, unlike phylloxera, leaf roll virus allows a crop to be produced and for it to ripen, but in many cases full physiological ripening never happens, resulting in green wines. I suspect the flavour profile of some South African reds, with sweet fruit and greenness at the same time, is caused by uneven ripening in vineyard blocks, with the virus affecting some vines more than others, or just infecting a few and others not at all. Pictured is an infected vineyard block in Vergelegen, which has been deliberately killed off with herbicides: the explanation I was given for this is that you can't just take the vines out and replant, because the soil-dwelling bugs that transmit the virus will still be there and reinfect the new vines. So you have to let the vines die, first. The vector in question is the vine mealybug (see article here), which is normally found on the aerial parts of the vine but which also has a subterranean part to its life cycle.

The mealy bug is fascinating - there's a good article, with a picture of its life cycle here. Ants are also involved in the story because they protect the mealy bugs, who give the ants a feed. Because it's difficult to eradicate plant viruses, current efforts in the war against leaf roll virus are concentrating on biological control (e.g. here) and genetic modification (which isn't allowed yet).

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At 10:02 AM, Anonymous keith prothero said...

A most interesting blog Jamie.
Leaf roll is a problem in many wine producing countries,including New Zealand and Australia,so if your theory on the "alleged' green streak is correct,I assume you would also detect this in those countries red wines,or indeed the many others that have the virus?
As you know,I live in the Cape for 6 months of the year,and probably taste at least 1000 different wines annually,75% of which would be red.
I suspect my palate is not as finely tuned as yours,but I seldom detect greenness,as described by you,and certainly not in quality wine.
Perhaps,you could name names,so that I could then do some research at this end,and see if in fact your theory stands up to examination.

At 9:33 AM, Anonymous Jean-Pierre Rossouw said...

This has been a contentious issue for a while now, with some commentators pushing our SA wines up in sugar ripeness at harvest to avoid "greenness" - which has in my view resulted in wines that are over-alcoholic. It would be useful to cross-reference these general comments with wines from known "infected" vineyards, so that this doesn't become a "SA style" (potential problem).

At 2:03 PM, Anonymous keith prothero said...

Yes I agree Jean-Pierre and thus I hope Jamie can provide a list of those wines that he particularly detects greenness and then lets investigate whether there is a correlation

At 7:03 PM, Anonymous Alder said...


Interesting and informative -- I wasn't aware that the leaf roll virus might be responsible for these flavors which I have come to fear every time I try a South African red. I assumed, like you, that it was just uneven ripening, or not enough destemming or both.

I know there are good SA reds out there, so I don't hesitate to try them when I get the chance, but sadly, on the whole they tend to disappoint.

At 6:48 AM, Anonymous Anonymous said...

Hi Jamie

Thanks for highlighting the problem. Why does it take an outsider to realise these faults when we have the institutions to study this very problem in SA. It all starts with viticulture, and while the WINE-MAKER is given so much emphasis in the production of SA wines and the viticulturalist is a trusty-guy that has been driving the tractor for 10 years, the problem will remain...


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