26 February 2021, UK: Yellow rust is making an appearance already this season on seedling susceptible varieties and despite the cold snap in February, the generally mild winter period means that we will need to remain vigilant with management.
It is not unusual to see active rust at this time. Yellow rust can be present at any time from pre-Christmas on many varieties, given that the majority of the Recommended List varieties are seedling susceptible.
The UK yellow rust population is both extremely dynamic and complex. As we have seen with several varieties over time, past performance is no guarantee of future performance and yellow rust populations can rapidly overcome adult plant resistance. It is therefore important to monitor all crops closely, regardless of their resistance rating, particularly following mild winters where rust levels may be starting to build up as we enter spring.
Due to variable weather conditions across the UK in autumn, there are crops which were planted over a wide range of drill dates. Some winter wheat went in very early and is likely to be harbouring significant levels of disease. Conversely, areas that suffered higher levels of rainfall have had drilling delayed, with wheat drilling continuing well into the New Year. Experience has shown that late drilled crops can express greater levels of yellow rust infection in spring, so these should also be closely monitored.
“If you observe active yellow rust at this point in the season, you should be prepared to treat it early to stay on top of it – particularly if growing varieties susceptible to yellow rust. A rust active T0 is often economic where there is high risk.”
– Seeds Technical Expert, Matthew Bull
To help monitor the spread of yellow rust across the UK, Syngenta have launched a new web-based service to help UK wheat growers and agronomists stay a step ahead of unpredictable yellow rust outbreaks.
The Rust Locator is available at www.syngenta.co.uk/rust-locator-2021. The tool uses an interactive map to record the locations of yellow rust infections, along with the variety affected, its yellow rust resistance rating and drilling date.