Corteva Agriscience is advising cereal growers to use the latest chemistry to help against the various challenges they face with flag leaf applications.
Sprays targeting septoria and rusts typically start in the middle of May but drilling date, variety and weather conditions have led to divergences in growth stages and disease prevalence.
Corteva’s field technical manager, Craig Chisholm, said: “Comparing crops across the country, we are seeing wheat which is only just having its T1 spray while other farms are preparing their T2 mixes.
“This will have been influenced by drill dates and varieties, but regardless of their growth stage crops generally look very good and have strong potential. The challenge will be getting T2 sprays on at the right time when there is not a great degree of uniformity.”
Catchy weather has meant that growers have been unable to travel at the optimum time to carry out control, with some T0 applications being abandoned altogether and T1 sprays taking place as and when windows presented themselves.
Combined with rising temperatures, Mr Chisholm explained that this has led to growing disease pressure. “There is plenty of septoria in the base of the crops in the trials we have been looking at and the warm, wet weather will contribute to infection further up the plant.
“Yellow rust has not been visible in many varieties until now – but is perhaps more evident in the south and west of England at the moment.”
Frontier’s crop production technical lead, Paul Fogg, said: “Septoria has not reached epidemic levels, but there is certainly more present than we’ve seen for a long time, probably driven by early drilling and temperatures over the winter.
“But autumn crops are looking good. Those who managed to execute their programmes this spring are definitely in the driving seat.”
Mr Chisholm added that growers should use fungicides with protectant and curative qualities to tackle the various challenges.
“Getting the timing of T2 sprays perfect is going to be a real challenge this year – it’s going to be easy to be a bit early or a bit late, so you need a fungicide that will stop disease taking hold, or act on any diseases that are present in the plant.
“Univoq has proven its ability to deliver curative and preventative persistence against yield-robbing diseases, perhaps most notably in 2021 when a wet spring created similar circumstances to what we are facing today.”
Eliciting the best possible yield response when applied at T2, Univoq is said to help contain latent disease and protect the crop for up to six weeks.
Mr Fogg said: “The season seems to be playing into the hands of the Inatreq molecule because of its disease control and longevity – it’s a long way to harvest so growers want something that’s going to stay the course.
“There will be decisions to be made around rates; 1.25l/ha is going to be a good starting point for many, but there are high-pressure situations already, and for those whose crops aren’t ready for a flag leaf spray yet, there is still time for pressure to build in this wet and warm weather.”
Standard application rates at T2 are 1.25 litres per hectare, although Corteva states that this can be increased to 1.5 litres in targetted areas of high disease pressure, or where the gap between T1 and T2 applications has been extended.
Trials in 2021 indicated that in the correct circumstances, increasing the application rate gave 0.15 tonnes per hectare yield benefit, worth around £33 per hectare at the current values.
For more information go to www.corteva.co.uk
