Spraying opportunities are often limited in spring so identifying fields to prioritise for treatment is key to effective disease control.

Omnia’s wheat disease risk forecasting model is a valuable tool to help do this according to Hutchinsons head of ICM, Dave Howard.

“The model is based on factors including; Recommended List variety scores, drilling date and critically historic and forecast weather data from the Omnia Climate module, which gives growers a visual representation of where the main risks are and strategically plan control programmes accordingly.”

He points out that this is particularly true for varieties with medium Septoria resistance scores (RL rating 5-6), sown around late September and early October.

“Temperatures fluctuate quite a lot at that time of year, so 7-10 days variation in drilling date can make a big difference to the speed of disease movement and risk going into spring.”

Last year showed that given the right conditions it can take off rapidly later, even from a low base disease level. So, Mr Howard added the Omnia model is being further developed to provide a way of predicting the severity of Septoria infections based on weekly rainfall data.

“We saw a lot of rust, mildew and Septoria on lower leaves at the start of the year, and generally thick, early-sown crops will be at higher risk if conditions are conducive,” stated Hutchinsons technical development director, Dr David Ellerton.

“Focus of the first fungicide spray should be yellow rust control, and it’s important to knock it out early with a tebuconazole or metconazole-based fungicide.”

Dr Ellerton advises when planning spray programmes, prioritise susceptible varieties rated 3 or 4, such as Skyfall, KWS Kinetic, KWS Zyatt or RGT Wolverine.

“Varieties with higher Recommended List ratings cannot be ignored, especially if it is based on adult resistance, which may not kick-in until late in the season. If disease establishes early, it can cause significant damage before adult resistance takes effect, so needs controlling.

“Straight tebuconazole or azoxystrobin cannot be used pre-GS 30, so check with your agronomist."

Following the withdrawal of multi-site chlorothalonil, folpet is now the main fungicide for Septoria protection where risk is high.

“The focus isn’t on curing Septoria that appeared on lower leaves over winter, it’s about protecting upper leaves as they emerge so it may be worth holding back folpet for the T1 and T2 and building plant protection in other ways.”

Where mildew is a threat, prothioconazole offers reasonable early season control, either as a straight product or in mix with tebuconazole or fluoxastrobin.

“The biostimulant Scyon can play a useful role as it's combination of naturally occurring, signalling metabolites strengthens the plant’s natural defences and maximizes nutrient uptake.

“If you’ve got a high-risk variety for Septoria, Scyon at T0 is worth considering and improving nutrient uptake is always beneficial, especially if growers are looking to apply less nitrogen fertiliser this season,” he says.