Septoria tritici: the ‘Cougar’ effect in RL winter wheat trials

The Recommended Lists (RL) currently features winter wheat septoria tritici disease resistance ratings based on one-year and three-year data sets. Mark Bollebakker, a senior field trials manager at AHDB, recently inspected an early sown winter wheat trial site in North Yorkshire (Croft-on-Tees). From a septoria tritici perspective, the early sown trial series is interesting, as plants are exposed to disease ascospores for longer. Consequently, they tend to have relatively high levels of disease, especially early in the season. Recently, conditions have been warmer and wetter. This has favoured the build-up of septoria tritici, which has provided an opportunity to glean an early insight into the performance of varieties. When the fungicide-untreated block was inspected, septoria symptoms were clearly present at high levels in some varieties, especially on the lower leaves. Following an inspection of varieties with various levels of septoria symptoms, Mark concluded that the one-year ratings may better reflect the disease levels being observed in 2022. Varieties with Cougar in their parentage do appear to have been most impacted by recent changes in the septoria tritici pathogen population. For further information, visit www.ahdb.org.uk/rl ABOUT AHDB AHDB is a statutory levy board. Our purpose is to be a critical enabler, to positively influence outcomes, allowing farmers, growers and others in the supply chain to be competitive, successful and share good practice. We equip levy payers with easy to use products, tools and services to help them make informed decisions and improve business performance. Established in 2008 and classified as a Non-Departmental Public Body, AHDB supports the following industries: meat and livestock (Beef, Lamb and Pork) in England; Dairy in Great Britain; and Cereals and Oilseeds in the UK. For further information visit www.ahdb.org.uk