Successfully managing wheat crops requires season-long planning and adapting fungicide programmes to the seasonal weather risks. As wheat ears emerge from late May, it is important to accurately time T3 fungicides to protect yield and quality in both milling and feed varieties. The T3 ear fungicide serves three important roles which should be considered in any fungicide strategy. These include controlling ear diseases such as fusarium ear blight, topping up foliar disease control and extending green leaf retention.
Growers should always undertake their AHDB mycotoxin risk assessment at early ear emergence. There are legal limits for Fusarium mycotoxins DON and ZON in wheat intended for human consumption and guidance limits for grain destined for animal feed. High levels of mycotoxins can lead to the loss of milling premiums, or even crops being rejected altogether. While other species such as Microdochium nivale do not produce mycotoxins, they can have a severe impact on grain yield and specific weight, as experienced in the 2012 harvest.
For the best control of the Fusarium complex and mycotoxins, T3 fungicides should be applied at full ear emergence, but before flowering has started. I recommend the use of angled nozzles alternating forwards and backwards to ensure the best coverage of the ear. Always use the appropriate fungicide dose for the risk- the most effective triazole being prothioconazole which is effective on all Fusarium species and Michodochium.
Brown rust is also a major consideration for determining the need for a T3 fungicide in the South East of England. Varieties such as Crusoe are highly susceptible to this disease and almost always justify the application of a T3 fungicide. In the highest risk situations, a T4 fungicide application may also be required to extend green leaf protection. Prothioconazole is weak on brown rust and in this scenario, I would advise the addition of tebuconazole or a rust active strobilurin. Prosaro (prothioconazole + tebuconazole) or Firefly (prothioconazole + fluoxastrobin), are my preferred choice of fungicides at T3.
Wheat crops are forward this spring and are racing through the growth stages. Consequently, the spray timings for fungicides look to be a week earlier than normal. A cool, bright and sunny June is often the weather pattern that maximises wheat yields and helping to extend green leaf retention with fungicides and nutrition will ensure growers achieve full yield potential.