Despite huge awareness campaigns, many South African grape farmers are still not taking grapevine leafroll disease, caused by a virus, seriously enough. Vinpro consultant François Viljoen said during a leafroll information session held at Vergelegen wine estate near Somerset West, Western Cape, that he simply could not understand why: "By now it is general knowledge that leafroll virus negatively affects farm income, as it results in lower production volumes and grape quality.
"It also significantly reduces the longevity of the vineyards, meaning vineyards should be replaced over shorter periods. You will be lucky if a leafroll-infected vine lasts longer than 15 years." Prof Gerhard Pietersen, a plant virologist at Patho Solutions, said the virus is severely underestimated in the table grape industry: "We tested 145 vines from 25 vineyards in five major table grape-producing regions between 2017 and 2020. The virus was found in every vineyard we sampled, and over 110 of the samples tested positive."
Despite this, he did not know of any table grape farmer who followed a leafroll management strategy like the one used in the wine grape industry. "Farmers in the table grape industry seem to be less aware of the negative impact of leafroll virus on production. This is probably because the virus takes a few years to manifest symptoms on vigorously growing vines, and table grape vineyards are replaced over a much shorter time than wine grape vineyards, in response to changing market trends and genetic improvements," he said.
Nevertheless, the virus is taking a toll on table grape income. Pietersen pointed out that Patho had identified leafroll virus as the cause of poor colouration on Crimson seedless grapes in a study done between 2019 and 2021. Research on wine grapes had also revealed that leafroll led to uneven ripening and berry sizes.
Denne historien er fra August 09, 2024-utgaven av Farmer's Weekly.
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Denne historien er fra August 09, 2024-utgaven av Farmer's Weekly.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
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Syngenta Seedcare celebrates a decade of innovation
Syngenta's ambition is to enable their customers' investments to grow in healthy soil from treated seeds to young plants through innovation and collaboration, writes Magda du Toit.
Agri workers shine at Western Cape awards
Lindie-Alet van Staden, a garden and olive orchard manager at L’Ormarins Wine Estate in Franschhoek, was crowned as the Western Cape Prestige Agri-Worker of 2024 at a gala event recently held near Paarl.
Small and large farmers recognised at grain awards
The annual Grain SA/Syngenta awards ceremony bears testimony to the quality of farmers in the grain industry.
Growing partnerships: Fedgroup's flexible and innovative approach
Janine Ryan spoke to Warren Winchester, general manager of impact investing at Fedgroup, about why the company became involved in agriculture, and what it offers farmers and their immediate communities.
Why fish farms fail, and how to avoid becoming a statistic
The popularity of launching fish farms is not matched by their success. Leslie Ter Morshuizen, owner of Aquaculture Solutions, explores the factors that cause most of these businesses to go under.
Where history and modernity meet in a luxurious setting
Brian Berkman kept his eyes peeled for ghosts in the oldest continuously run hotel in South Africa, but all he found was a fabulous two-night stay.
THE HITCHING POST
I'm a stylish elderly lady with a radiant glow and a good sense of humour that keeps me young at heart.
Cutworms: check the weeds on your fields!
Zunel van Eeden explains why understanding the ecological interplay between cutworms and weeds is crucial for effective pest management. Producers should disrupt the life cycle of cutworms to minimise crop damage.
Does high-density grazing mimic grazing patterns of game?
In their paper on high-density grazing in Southern Africa, professors Angelinus Franke and Elmarie Kotzé from the Department of Soil, Crop and Climate Sciences at the University of the Free State say high-density grazing systems may not accurately reflect natural ecosystems. Roelof Bezuidenhout reports.
Global grain outlook: 2024/25 marketing season
In its latest summer crops report, the Crop Estimates Committee says South African farmers intend to plant 4,47 million hectares of summer grains and oilseeds in the 2024/25 season, up 1% from the previous season. As South Africa exports maize and soya bean, Annelie Coleman reports on the latest trends in the international grain and oilseed markets, amid fluctuations in weather conditions and ongoing armed conflicts.
