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.
この記事は Farmer's Weekly の Farmers Weekly 8 November 2019 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
すでに購読者です ? サインイン
この記事は Farmer's Weekly の Farmers Weekly 8 November 2019 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
すでに購読者です? サインイン
Review: the Toyota Hilux 2.8GD-6 DC 4×4 GR-Sport III
The third iteration of the Hilux GR-Sport has finally achieved a sense of presence and style befitting its raceinspired branding. But is this the ultimate modern Hilux? Car Magazine takes a closer look.
Why maize prices soar in Kenya and Malawi but not Tanzania
Namhla Landani, an economist at the Centre for Competition, Regulation and Economic Development, University of Johannesburg, and Arthur Khomotso Mahuma, economist and researcher at the Centre for Competition, Regulation and Economic Development, University of Johannesburg, analyse the issue.
Wet carcass syndrome: a scourge in SA sheep farming
Wet carcass syndrome continues to take a huge financial toll on South African sheep farmers. Octavia Avesca Spandiel spoke to two experts about the ongoing genetic research aimed at addressing this issue.
Pollination innovation
Bee-Tech Group is transforming South African agriculture with pollination technologies that boost crop yields and enhance sustainability. Founder Michiel Bruggeman spoke to Octavia Avesca Spandiel.
The valuable addition that makes this farm tick
Owning the value chain provides farmers with far more control over their produce. However, it requires a fine balance between production and ensuring there is a strong and steady market. Lindi Botha visited Rosemary Hill to find out how this essential oil producer leverages hospitality to make the farm viable.
The benefits of recirculating aquaculture systems
A powerful set of attributes has established recirculating aquaculture systems as a cornerstone of global temperate fish farming, writes Leslie Ter Morshuizen, owner of Aquaculture Solutions.
Minister has big plans for emerging and commercial farmers
DA leader and Minister of Agriculture John Steenhuisen spoke to Glenneis Kriel about his priorities for his department over the next five years, including an increased focus on biosecurity.
New study aims to make wheat more disease resistant
A recent international study explains how bread wheat has helped to transform the ancient world on its path to becoming the iconic crop that today helps sustain a global population of eight billion.
Conservation farming and biodiversity boost soil health and sustainability
A recent academic event focused on research into the links between soil biodiversity, soil health and sustainable agriculture
What has led to the unparalleled rice shortage in Japan?
Japan is facing a rice shortage amid concerns about a potential 'megaquake', several typhoons and an annual week-long holiday, which has led to an increase in panic buying.