GROWERS worried about sclerotinia infection risk to their oilseed rape crops can soon tune in to the AHDB website for help in deciding if, when and where to spray.

Based on a simple traffic light system, the forecasts show the potential infection risk level at 15 oilseed rape monitoring sites – two of which are in Scotland, in the Border and near Edinburgh.

The information can be used, alongside in-field data, to assist with the targeting of sprays. Automated spore trapping from a connected research project, is opening up the opportunity for real-time spore pressure data for key diseases, including sclerotinia, said the AHDB.

The causal agents of sclerotinia germinate in spring soils and produce fruiting bodies which release airborne spores. Some of these are carried onto petals which fall and stick to leaves or leaf axils, especially if there is light rain.

Caroline Young, who works on the forecasts at ADAS, said: “Whether a crop is at risk from infection depends on multiple factors. Fungal inoculum pressure during flowering is particularly important. In fact, our research shows that if petal tests come back clean, then the need to spray against sclerotinia is radically reduced.

“If petals carry inoculum, then weather conditions become critical. Our weather model triggers an infection alert when relative humidity is greater than 80% for more than 23 hours and temperatures are at, or above, 7° C.”

The weather-based forecasts, combined with inoculum results, help show if crops located at the monitored sites could benefit from an initial treatment with a protectant fungicide (which typically offer three weeks’ protection) and a follow-up spray.

* This is the third year that AHDB will show the weekly risk alerts, which are likely to start as early as next week – the news can be accessed at cereals.ahdb.org.uk/sclerotinia