Thursday, January 27, 2011

End of Leafroll?

It seems an end is in site for South Africa's other big virus problem. By 2013 - assuming the Mayan calender does not come to pass - some producers including Stellenzicht will be planting leafroll virus resistant vines. However this has not occured through technology (but dont tell Thabo & Manto) but rather through good old fashioned foot slog and natural selection (no beetroot juice involved either).

Not yet Autumn

By observing infected vineyards over two seasons, consulting viticulturalist Eben Archer identified naturally resistant vines in heavily infected blocks and has propagated these for replanting of vineyards. Although these came up clean in local tests - and in the USA and France - Archer will only let time reveal if he has been successful.


The Shiraz, Pinot Gris & Pinot Noir identified by Archer will be made available through the national clonal selection scheme for commercial grafting. We can expect the first harvest in 2016.

Meanwhile others are thriving with the virus. 'Leafroll virus gives us marginality' says Hamilton Russell Vineyard's (HRV) Anthony referring to how many great vineyards of the world including Burgundy thrive on a viticultural knife-edge where natural cause and circmstance limit both vigour and yield and grapes only just reach ripeness. These wines often have great balance, length, intensity and complexity.

 
Anthony sets up stall
While uneconomical for most, Anthony also lives with very low yield. Viticulturist Johan Montgomery and winemaker Hannes Storm - now approaching 10 vintages at this SA icon - are ruthless in their crop thinning reducing strong canes to two bunches, moderate to one and weak to none!

Anthony also believes their clay rich soils are a major contributor to their Burgundian style wines.  Restraint is another feature and I also enjoyed the moderate alcohols that are increasingly difficult to find.


Geek Philosophy
One of the biggest challenges in controlling leaf role virus is that it is spread by a wood louse known as mealy bug. Besides wintering underground mealy bugs live in symbiosis with ants which are virtually impossible to control so new plantings are quickly re-infected.

No comments:

Post a Comment