In this article, we look at diseases that can affect sunflower crops in South Africa. While some are more common than others, all those listed here can cause severe yield and economic losses.
Foliar diseases of sunflower are caused by various pathogens, including Alternaria helianthi, Puccinia helianthi and Septoria helianthi. They cause various symptoms on foliage, which may result in lower sunflower yields during seasons that are favourable to their development.
The ideal environmental conditions for the development of these diseases vary, and so correct disease identification is crucial for developing appropriate disease-management strategies for each.
ALTERNARIA LEAF SPOT
Alternaria leaf spot is a major defoliating fungus that occurs in warm, humid climates all around the world, according to the Agricultural Research Council (ARC). There are many species that cause leaf spot, but A. helianthi is the most common. A. helianthi overwinters on infected plant residue, the ARC explains, but wild sunflowers can also be reservoirs. A. helianthi seeds are also wind-borne.
The optimal temperature for the germination of the fungus is above 26°C, and at least four hours of wetness are required. Seedlings are the most prone to infection.
What to look for
Alternaria causes linear spots on the stem of the plant, as well as sunken, water-soaked lesions on the back of the head, says the ARC. However, the council warns that all Alternaria species cause similar symptoms, making it difficult to identify the particular species in-field.
FAST FACTS
Esta historia es de la edición Farmer's Weekly 6+13 January 2023 de Farmer's Weekly.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor ? Conectar
Esta historia es de la edición Farmer's Weekly 6+13 January 2023 de Farmer's Weekly.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor? Conectar
Understanding eye conditions in horses: causes and first aid
A horse can get a swollen eye from bumping it against a tree, shaking its head to keep flies away, or even snake venom
IPM requires a completely different mindset
You need to investigate any beneficial insects that may appear on your plants, or you can purchase them
Does parrot farming protect wild species?
Those in favour of commercial captive breeding argue that breeding parrots to sell can relieve pressure on wild populations. Researchers Neil D'Cruze and Rowan Martin review the evidence.
Bacterial and fungal diseases of garlic
Garlic can be prone to bacterial and fungal diseases, and it's important that farmers are proactive in preventing infection and practise appropriate management. Magda du Toit reports.
Responsible wastewater management: a crucial part of farming
The inadequate management of waste water is a challenge that the agriculture sector needs to deal with. Magda du Toit spoke to experts in waste and water management about a cost-effective treatment system.
Technology that can help protect South Africa's farms
Farm attacks, murders, livestock and crop theft, and other rural crimes are a growing concern in South Africa. As a result, more and more farmers are turning to advanced security technology to protect their lives, properties, and livelihoods. Sinenhlanhla Mncwango spoke to experts about the security strategies that producers can adopt to combat these threats.
The impact of theft on farms in South Africa
A high number of livestock are being stolen every year in South Africa. Insurance is expensive and farmers are battling to find solutions to the problem, says Dr Lindie von Maltitz, agricultural economics lecturer in the Faculty of Natural and Agricultural Sciences at the University of the Free State.
Staying afloat amid the cost-price squeeze
John Hudson, head of agriculture at Nedbank Commercial Banking, spoke to Glenneis Kriel about the importance of environmental and social sustainability for a prosperous agriculture sector.
Free State has no reason to mark Transport Month
Free State Agriculture (FSA) is very concerned about the extremely poor state of rural paved and gravel roads in the province and has very little, if anything, to celebrate during Transport Month, which takes place every October.
SA's food system ‘vulnerable to climate change'
The Just Transition Agenda for Food System Policymaking in SA webinar, hosted by the Institute for Economic Justice (IEJ) in October, highlighted the role that South Africa’s food system plays in contributing to climate change and how vulnerable it is to the impact thereof.