Sweet potato (Ipomoea batatas Lam.) is produced commercially, as well as grown by subsistence and smallscale farmers, as an important and reliable food source. Unfortunately, like several other crops, sweet potato is prone to virus infections, which are associated with substantial yield and quality loss. Recent research at the Agricultural Research Council (ARC) has shown that mixed infections of begomoviruses, such as the sweet potato leaf curl virus, and potyviruses such as the sweet potato feathery mottle virus, have a detrimental effect on sweet potato production.
Virus-infected sweet potato vines used as planting material act as sources of infection and can transmit viruses from one place to another.
More than 30 viruses occur naturally in sweet potatoes worldwide. Some of the more important ones in South Africa are described below.
Sweet potato feathery mottle virus and sweet potato virus c
Sweet potato feathery mottle virus and sweet potato virus C are transmitted by the aphid species Myzus persicae and Aphis gossypii. An aphid can acquire the virus from infected plants in less than a minute while feeding, and transmit it to a healthy plant in seconds. Leaf symptoms vary with cultivar, climatic conditions and plant age.
Sweet potato virus C was previously called the C strain of sweet potato feathery mottle virus. However, comparison of the coat protein amino acid sequences revealed that it is distinct from other strains of sweet potato feathery mottle virus.
• Symptoms Leaf symptoms include a diffuse mottled effect, faint to distinct chlorotic spots, which may have purple pigmented borders, and irregular chlorotic patterns (feathering) along the main veins (see Figures 1A, 1B and 1C). Symptoms are usually found in older leaves. Severely infected plants are stunted and their leaves are smaller.
This story is from the Farmers Weekly 8 November 2019 edition of Farmer's Weekly.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the Farmers Weekly 8 November 2019 edition of Farmer's Weekly.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber? Sign In
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.
