Tailoring disease control to risk through ICM – Farmers Guide – David Howard, David Ellerton
Hutchinsons head of integrated crop management, Dave Howard shares his views on how disease control in wheat can be achieved within an ICM approach this season ...
Integrated Crop Management does not require a drastic change from the norm – in fact, many ICM principles have already been taken up over the years due to the positive effect they can have on disease management.
It’s simply a more strategic approach to planning which crops and varieties to grow, assessing where risks lie and then adapting management and inputs in response to changing weather patterns and disease levels – or visualising risk.
Understanding disease risk based on early cropping decisions like variety or drilling date, and in-season monitoring of crops, is the key to using ICM successfully – which is something many farmers are already doing without fully realising it.
David Howard, Head of Integrated Crop Management
To make this process much simpler, Hutchinsons has developed a Wheat Disease Risk Forecasting model within Omnia. This model automatically calculates which crops are at the highest risk from disease, taking into account all of the factors affecting disease developing in the crop – allowing the user to tailor a fungicide approach accordingly.
It’s about being better informed to plan a strategy; the job of the model is not to tell us that a disease is present, but rather to plan for what disease will be more likely to develop in a particular variety/field etc.
This allows the user to temper that risk as much as possible, not eliminate it, by tailoring a planned fungicide approach accordingly. Factors affecting disease risk in wheat crops:
- Varietal susceptibility based on AHDB RL ratings
- Drilling date
- Rotational position
- Current and forecasted weather
- Local disease levels
The model effectively takes into account the data already entered into Omnia, such as variety and drilling date, alongside the climatological data provided by the Climate tool to generate a visual risk map across the farm, illustrating which fields pose higher risks and where that risk is coming from.
The weather data within the model is supplied through Omnia’s well-established Climate module, providing extremely accurate current and forecasted weather conditions for locations down to a 1km resolution.
Users can allocate specific fields and are presented with a sliding scale to access visual representations of crop growth and certain growth stages. Likely spray days are then predicted, and as the weather patterns change, the calculated risk constantly evolves and fungicide programmes can then be planned more effectively.
The risk is recorded through the season to provide data for justification purposes, which is something that is becoming increasingly important.
Plans are to develop a similar model for barley, and a Lodging Risk model for wheat – all of which are being trialled this spring on our Helix farms.
Managing disease risk
The gap between T0 and T1 sprays should not exceed 3-4 weeks, and the decision on active ingredients to include in the T1 spray is determined by risk; risk from varietal susceptibility, drilling date, position in the rotation, weather conditions and location, and what was applied at T0.
An anti-resistance strategy needs to be strongly considered, only using certain modes of action where they are necessary – which is best achieved by tailoring the fungicide programme to risk.
This risk can now be calculated within the Disease Risk Forecasting model in Omnia, allowing for an appropriate fungicide programme to be planned, based on predicted levels of risk.
Dr David Ellerton, Technical Development Director
Hutchinsons technical development director, Dr David Ellerton, gives his views on how to manage disease risk at this key timing.
“Septoria remains the main disease in winter wheat, with pressure heavily dependent on rainfall in April and May. Susceptible varieties rated less than 5 should be prioritised for treatment. The strongest active against septoria is mefentrifluconazole, commonly known as Revysol. It should only be used where septoria risk is high, as with all actives, the more it is used, the higher the chance there is of resistance developing.
“For varieties that are at significantly lower risk from septoria, prothioconazole-based products work effectively, particularly if mixed with an SDHI.
“The strongest individual SDHI for septoria control is fluxapyroxad (Xemium) while benzovindiflupyr (Solatenol) gives good persistence and excellent control of rust. On varieties with the very highest septoria ratings, any additional SDHI will suffice.
“Including a multi-site such as folpet is also important and plays a crucial role in an anti-resistance strategy. Biostimulants such as Scyon also offer an alternative disease control option, and while it is best used at T0, it can be added in at T1 as an alternative.”
Dr Ellerton continues; “T0’s should have knocked out any early yellow rust which will take the pressure off at T1. If still present, additional tebuconazole may be warranted for quick knockdown while strobilurins, such as azoxystrobin or pyraclostrobin, give long-lasting protection plus physiological benefits.
Consider the physiological benefits of strobilurins such as increased rooting, particularly given the wet conditions that we have had; rooting will be shallow, and if we move into a period of drought later in the spring, this could be an issue for crops.
SDHI’s such as benzovindiflupyr (Solatenol) can also boost rooting and help the plant become more resistant to drought. Remember that strobilurins can only be used twice in any programme.
For the control of stem-based diseases such as eyespot and take-all, particularly in early sown second wheats, prothioconazole should be used. The addition of strobilurin fungicides, e.g. azoxystrobin or fluxastrobin, can help reduce take-all.
Any lurking mildew can be mopped up at T1 using cyflufenamid on more susceptible varieties, crops in high risk areas in the north-west, or on organic soils. Prothioconazole is also useful for mildew control.
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