As we now start to see Septoria creeping up the plant onto the unprotected leaf 2 and the recently emerged flag leaf, as well as brown rust developing in the more susceptible varieties such as Crusoe and even Graham, how do we tackle the task ahead to control disease effectively and maximise yield potential?
What chemistry do we need?
We need to use the best triazoles available to us, such as Epoxiconazole or a prothioconazole based material, at a minimum dose of 75%, a SDHI is an essential component at this T2 timing and a multi site product based on either Chlorothalonil or folpet. If rust is a concern, consider using folpet as your multisite or if you require more curative control from the triazole and SDHI. If both the T0 and T1 sprays have been well timed to keep Septoria on the lower leaves then chlorothalonil is an ideal partner.
When do we need to apply?
Sprays need to be applied once the flag leaf is at least 75% emerged. If previous timings have been delayed, ideally a robust T1 application will ideally give you 3-4 weeks protection but you can not afford to leave the flag leaf unprotected, so you may need to go back earlier. Yield losses of up to 50kg/ha per day can occur when flag leaf timings are delayed. We mustn’t settle for mediocre yields when better results can be achieved, which benefits your gross margin. Well timed fungicide programmes will deliver up to an extra 3t/ha on average.
Other factors to consider:
Many crops have shallow roots due to the wet soil conditions over the winter and early spring and have a resulting lower biomass than usual. Consider using further root enhancing materials or auxin based trace element combinations, particularly magnesium.