What Fusarium head blight is and how it appears
Fusarium head blight in wheat is caused by a complex of fungal species, mainly Fusarium graminearum and Fusarium culmorum. Infection develops between heading and ripening, especially during flowering, when exposed anthers provide the ideal entry point for the fungus.
The most visible symptoms include
Discoloured ears
Early drying of spikelets
Pale pink mycelium in severe infections
Shrivelled and wrinkled kernels
Reduction in hectolitre weight and thousand-kernel weight
The real risk: deoxynivalenol, or DON
The Fusarium species that attack wheat ears can produce deoxynivalenol, known as DON. This mycotoxin belongs to the trichothecene group, a class of toxic compounds with strong cytotoxic and immunosuppressive properties.
The main problem is that DON is extremely stable. It does not break down during storage, milling, processing or even cooking. This means that once the grain is contaminated, the contamination remains throughout the entire supply chain, all the way to the finished food product.
Legal limits and marketability
European regulations set strict maximum limits for DON in cereals and cereal-based products. If these thresholds are exceeded, the product cannot be placed on the market, resulting in immediate economic losses for growers and potential responsibility for buyers and processors who purchase grain without adequate controls.
- Loss of production: up to 50%
- EU limit for marketing and for grain: 1,000 μg/kg of DON in finished products intended for human consumption
Conditions that favour Fusarium and DON development
Three environmental factors and three agronomic factors determine the level of risk in each field and in each season.
Environmental factors
Rain during flowering
The infection window coincides precisely with flowering: rainfall and high humidity during this stage favour spore dispersal and the colonisation of exposed anthers.
Moderate temperatures
The optimal range for Fusarium graminearum is between 20 and 30 °C, which means that warm and humid springs can create highly favourable conditions for infection.
High relative humidity
High humidity supports fungal sporulation and keeps the ears wet for longer, extending the period in which infection can occur even beyond individual rainfall events.
Agronomic factors are just as important
Sowing wheat after maize or sorghum
Crop residues act as the main substrate where the fungus survives and reproduces. For this reason, crop rotation is one of the most effective preventive tools.
Minimum tillage and no-till systems
Conservation techniques that leave residues on the surface increase the availability of inoculum.
This is a major risk factor, particularly in tight crop rotations.
Varieties susceptible to Fusarium
Not all wheat varieties respond to Fusarium in the same way. Choosing more tolerant varieties, both under development and already available on the market, can significantly help reduce the problem.
The treatment window: three days that can determine an entire season
For the fungicide treatment against Fusarium to be effective, it must be applied within a 3–4-day window, between the start of flowering and the point at which 30 per cent of the anthers have emerged.
To identify the optimal time for intervention, it is essential to constantly monitor the crop’s phenology and to use DSS systems integrated with agrometeorological stations to predict periods of risk and support precise and timely agronomic decisions.
Prevention strategies: protection begins before the fungus appears
Chemical control is important, but it is not enough on its own. Control of Fusarium head blight and DON is achieved through an integrated system of preventive measures:
Crop rotation
Avoid sowing wheat after maize, sorghum or other cereals. Legumes are the ideal rotation crop for breaking the fungal cycle and reducing the inoculum in the soil.
Soil tillage
Ploughing buries crop residues and drastically reduces the availability of spores on the surface.
Variety selection
Over the last 15 years, research has developed genotypes with greater tolerance to Fusarium head blight, while still maintaining the agronomic and supply-chain characteristics required (productivity, protein quality and rusticity). Varietal selection is the most sustainable preventive measure, particularly in the context of climate change.
Managing Fusarium risk with APOD’s technical support
Agrometeorological stations, DSS models, variety consulting and field monitoring: OP Apod members have access to the tools they need to identify the correct treatment window and protect the quality of the grain they deliver.
Frequently asked questions about Fusarium head blight in wheat
What is Fusarium head blight in wheat?
Fusarium head blight in wheat is a fungal disease mainly caused by Fusarium graminearum and Fusarium culmorum, which affects wheat during the flowering stage. In addition to reducing yield, it can compromise grain quality.
Why is Fusarium head blight so dangerous?
Because it does not only cause yield losses: it can also contaminate the grain with mycotoxins, particularly deoxynivalenol (DON), making the product unsuitable for sale.
