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Half of SA's vineyards could be affected by leafroll

Published:  23 July, 2008

By James Aufenast

Half of South Africa's vineyards could be affected by leafroll virus, according to a leading South African winemaker. The winemaker, who would not be named, said South Africa was losing its older vineyards as a result: "Yield is down to nothing in the older vines. People are replanting like mad." He added that it was there for all to see: "If you look around in the vineyard in the autumn you can see the classic bright red and yellow colouring." Figures from South African Wine Information Statistics show a drop in total hectarage of red vines 16 to 20-years-old (down to 950 ha), compared to red vines under four years old (14,649ha). "It's a huge problem," said Peter Finlayson, viticulturist and winemaker at Bouchard Finlayson. "The aphids carrying the disease get into the cracks in the soil from ploughing, and they're hard to get to. We've had lots of problems with Chardonnay, so we've planted it in Overberg. It's less of a problem in the cool areas." "Early Chardonnay never ripens properly," said Irina von Holdt, wine writer and owner of Old Vines Cellars in Rosebank. "We have that old-clone, virus-infected taste in South Africa which is more tannic. To protect itself the plant makes more tannin. It's not unpleasant, though." Professor Eben Archer, who is working at theUniversity of Stellenbosch to combat the problem, said that 40-50% of Stellenbosch's red vines were affected. "It tends to affect red vines more than the whites." Archer said that everyone was asking why it should be that South Africa was so badly affected. He postulated: "Leafroll shows up in stress conditions, and many of our vineyards are stressed, with the hot dry summers, combined with the fact that many farmers do not irrigate. Australia irrigates many of its vineyards. "Leafroll is carried by mealy bug, and much of the material used for grafting in South Africa is not clean, but we are working on getting this right," said Archer. He added that the team at the university combating leafroll has developed a nursery, called Technogrow, which is completely free of the virus.