While the extent of losses in South Africa is uncertain, canola farmers in Australia generally lose between 10% and 15% of their harvests annually to blackleg, with figures as high as 90% being recorded in some instances. This is according to Dr. Gert van Coller, plant pathology scientist at the Western Cape Department of Agriculture and a speaker at a Knowledge Hub event presented by Syngenta and John Deere in Napier in the Western Cape in October.
Global losses to the disease are estimated at over R16 billion annually.
FUNGAL SPECIES
Blackleg is caused by two fungal species, namely Leptosphaeria maculans and L. biglobosa. These can affect any part of the plant and result in leaf and pod lesions, and stem and crown canker. L. maculans, the more virulent of the two, is by far the most common in South Africa. It causes crown canker, which has a major impact on yield by inhibiting nutrient and water transportation in plants, as well as stem canker and upper canopy infection.
L. biglobosa causes more superficial canker on the upper parts of the stem and is therefore less damaging.
To complicate matters explains Van Coller, there are a number of races of L. maculans, and scientists are currently researching the occurrence of these in the Western Cape, where most of South Africa's canola is planted.
DISEASE CYCLE
The blackleg pathogen survives on infected canola stubble left on the land after harvest. This produces fruiting bodies called pseudothecia, which are visible as small black dots on the stubble. These in turn release sexual spores, called ascospores, after the first autumn rains, with 2mm to 3mm of rain being enough to initiate the disease.
この記事は Farmer's Weekly の December 02, 2022 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 December 02, 2022 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
New farmers' seedling pitfalls
Inexperienced farmers may be tempted to grow seedlings from seed themselves, but they have much to gain by trusting a seedling grower at a nursery to perform this task for them instead
South African avocado production: a success story
Avocado production in South Africa has expanded markedly since the industry's humble beginnings over 80 years ago. From a small grove planted in 1938 in what was then Nelspruit, the industry has blossomed to seven million trees planted on 20 000ha. Dr Guy Witney, project manager at Great Brak Avos, spoke to Annelie Coleman about the country's avocado production.
Unlocking value through livestock exports
Exporting livestock might sound like a daunting business that's better left for big companies, but Gerrie Ferreira, who farms near Oudtshoorn in the Western Cape, has been doing it successfully for almost 30 years, sometimes in partnership with other breeders. He spoke to Glenneis Kriel about the huge potential this market holds, and offers some advice for farmers who are contemplating going this route.
An agribusiness's dedication to community upliftment
For agribusiness NWK, located in Lichtenburg, North West, corporate social investment is an important part of creating a positive influence alongside financial returns. Johan Bezuidenhout, NWK’s group manager of corporate marketing and communication, spoke to Annelie Coleman about why the company chooses to invest millions of rands in the area it operates in every year.
Empowering dreams, transforming lives
Since its launch in 2013, the Agri's Got Talent competition has revolutionised the lives of many farmworkers by unlocking their hidden talents and fostering a culture of empowerment. Glenneis Kriel spoke to various finalists about how the contest has changed their lives.
Foreign investment: agriculture maintains its appeal
South Africa remains a popular destination for foreign investors, despite an often negative outlook from its citizens. It is a gateway to Africa, and with its counterseasonal production to the Northern Hemisphere and favourable weather, local agriculture is especially well placed to attract foreign interest, bringing with it hope for rural communities
The real value and message of COP29 for SA agriculture
While the 2024 Conference of the Parties may have disappointed those who hoped for real progress, it's more important for South African agriculture to highlight its role in carbon mitigation
Improving efficiencies in feed and grain milling
Bühler, a Swiss-based company that provides solutions and equipment for various industries, including food and animal feed processing, has pledged that by 2025, it will deliver scalable solutions that will reduce energy, waste and water by 50% in the value chains of its customers.
Tips for better olive production
At an SA Olive Association field day in November, industry experts shared ways to improve olive production efficiencies, from soil preparation to harvesting.
More effort needed to protect vulnerable cheetah
On International Cheetah Day, commemorated every year on 4 December, emphasis was placed on the vulnerability of the species.
