The UK is primed for a mass eruption of phoma leaf spot spores during early to mid-October, according to experts. The warning was issued alongside the critical October update of the AHDB Cereals & Oilseeds-funded phoma leaf spot forecast.
Hosted by Rothamsted Research, the forecast uses temperature and rainfall data (from the summer to early autumn period) to provide information on potential disease pressure and guide spray decisions against phoma.
With plenty of rain throughout August and unsettled conditions predicted for the foreseeable future, all UK regions are forecast to be at risk from a mass eruption of airborne spores during early to mid-October.
Due to the importance of localised rain/wetting events, the timing of visible leaf spot symptoms is forecast to vary tremendously across the UK.
Compared to last year, some sites are forecast to have earlier onset of symptoms, some similar and some later.
Dr Neal Evans, Weather INnovations Consulting LP, who puts the forecast together, said: “The UK forecast map is based on more than 80 sites and is updated daily to show when each site is predicted to have 10% leaf spotting, which is the established threshold for treatment.
Thus, the map can guide spray decisions but, as localised rain events play such an important role, nothing beats walking the crop and inspecting the leaves.”
For the latest information, visit the OSR disease management pages.