The use of a multisite cereal fungicide should be the first product in the spray tank, and then growers should decide whether to add an azole or SDHI product.
Fungicide expert Jonathan Blake at crop consultant Adas says three multisite protective fungicides – folpet, chorothalonil and mancozeb – are the foundation of any fungicide strategy for wheat and barley.
These three fungicides have been used by growers since the 1960s, and they have shown no signs of disease resistance.
This comes at a time when the two key systemic fungicide groups for controlling septoria in wheat – azoles and SDHIs – are showing a slow decline in efficacy against this yield-sapping disease.
“Growers should maximise what won’t develop resistance and minimise those that develop resistance,” Mr Blake said.
“We need to maintain the chemistry for as long as possible and so devise programmes based around products that show no resistance,” he added.
Chlorothalonil is currently going through a reregistration process and its long-term future is uncertain.
He suggested growers look at other methods to try to reduce the risk of fungicide resistance, such as late drilling and using wheat varieties with good disease resistance.
“If you drill later with a good resistant variety then there is less need for two SDHIs,” Mr Blake said.