No wheat farmer wants their crop to be hit hard by the destructive fungal disease Fusarium ear blight. Not only does it reduce yields, but the fungi involved can produce poisons (mycotoxins) dangerous to humans and livestock, and strict legal limits are in place for mycotoxins in grain destined for human consumption and animal feed.
ENDURE’s wheat case study team has now produced an eight-page guide outlining the strategies that can be used to control Fusarium ear blight, which is proving to be an increasing problem in many parts of Europe, including Germany, France, Denmark, Italy and Hungary. The guide is part of ENDURE’s From Science to Field series, aimed at agricultural advisers and extension services and of equal interest to farmers.
The guide is particularly important as the chances of a crop being hit hard by Fusarium can be much reduced by changing agricultural practices without the need for fungicides. And, as the authors note, while fungicides applied to the ear during flowering can reduce the incidence and severity of Fusarium ear blight, in high-risk seasons high levels of control are unlikely to be achieved.
Several species of Fusarium can affect wheat – not all of them produce mycotoxins – and it is possible that several species can infect the same ear, the severity of attack depending mainly on weather conditions during flowering (warm and wet conditions are the worst) and a combination of agricultural factors.
Reducing the risks
The authors have identified a strong link between the risk from Fusarium and crop rotation and tillage methods. There is a particularly high risk in regions where maize is a widely grown crop in the rotation.
Direct drilling and reduced tillage (soil preparation), which leave debris on the surface that can act as a source of inoculum, also increase the risk of Fusarium ear blight. In some countries growing wheat after wheat in combination with minimal tillage has also been found to increase the risk.
Ploughing can significantly reduce the risk and the authors also identify cultivar choice as another important factor. They note that while no cultivar can give 100% control of Fusarium ear blight, cultivars with high levels of resistance are available. Several countries rank each year the relevant cultivars for susceptibility to Fusarium ear blight.
The authors provide an example of a decision key that can be used for evaluating the risk level for DON (deoxynivalenol, one of the mycotoxins produced by Fusarium ) in a given field, which shows that the right combination of agricultural practices can dramatically reduce the DON risk without the use of fungicides. They also provide advice on grain sampling, and suggest that it is good practice to sample every trailer load of grain, taking samples of at least 1kg.
More about Fusarium
Fusarium is the name for a large family of fungi widely distributed in soil and associated with plants. There are several species of Fusarium that affect wheat, the main ones being F. avenaceum, F.culmorum, F. graminearum, F. poae and F. langsethiae . Microdochium nivale and M.majus also affect wheat and may cause head blight. However, Microdochium species do not produce mycotoxins; they are the main cause of seedling blight.
Fusarium mycotoxtins – American scientists call them vomitoxins, which gives a clear idea of their effect – have been associated with thousands of deaths. Researchers believe Fusarium mycotoxins were responsible for mass casualties in the Soviet Union in the 1930s and 1940s, when contaminated wheat flour was used to make bread. This caused alimentary toxic aleukia (ATA) which, according to mycology expert Abraham Joffe, killed an estimated 100,000 Russians between 1942 and 1948.
In contrast, one Fusarium species (F. venenatum ) is the basis for the meat-alternative Quorn, sold in many European countries by Marlow Foods. F. venenatum is grown in fermentation tanks, glucose, vitamins and minerals are added and the resulting mycoprotein is heat-treated and bound together with egg whites to form the foodstuff that has proved popular with vegetarians.
About the wheat case study team
ENDURE’s wheat case study team brings together researchers from eight ENDURE partners, in addition to the Arvalis technical institute in France. The team has produced two From Science to Field Guides, which can be downloaded below:
To download Using Cultivar Resistance to Reduce Fungicide Input in Wheat , click below:
To download Strategies to Control Fusarium Ear Blight and Mycotoxin Production in Wheat , click below: