Septoria Tritici Blotch in Commercial Wheat Crops in England: The Use of Fungicides for Disease Control

Fungicides are used to control Septoria tritici blotch in winter wheat ( Triticum aestivum ) in England. In this paper we analysed data from a long‐running survey of commercial winter wheat fields and explore how the use of foliar‐applied fungicides has changed over the period 1985–2019. One of the aims of the analysis was to determine to what extent growers followed guidance on fungicide treatment and fungicide resistance management. Guidance suggests restricting fungicide treatments to key growth stages (GS, Zadoks growth stage). In the UK, these are commonly referred to as the T0, T1, T2 and T3 timings, which correspond approximately to GS30, GS31–33, GS39 and GS59–65, respectively. For Septoria tritici blotch the T1 and T2 timings are the key timings. Our results show that most growers adhered to this treatment timing guidance. The T1 and T2 timings were the most frequently used and had the highest efficacy. Current resistance management guidance suggests using alternation or mixtures of modes of action (MoAs) rather than using a single MoA sequentially. The data show that the number of MoAs used per farm and per crop increased from two around 1990 to three from 2010. The data showed that the number of mixtures used has increased considerably and there are few treatments nowadays not consisting of a fungicide mixture. The concept of ‘treatment according to need’ where the grower is guided to use fungicides as needed to maintain effective disease control, but not more, is followed to some extent by growers.