2017 - Integrated disease management – taking the holistic approach to combat Septoria
To achieve effective Septoria control, growers should adopt the 'prevention is better than cure' mantra. This means looking beyond the can to protect crops, with variety choice, drilling date and cultural techniques all playing an important role.
Airborne Septoria ascospores are always present from the previous harvest, so rotations and cultivations alone will not control the disease or limit its spread. Effective management therefore requires a package of chemical control measures used in parallel with a series of cultural approaches: selecting disease resistant varieties, later drilling date and improved crop husbandry.
Early sown crops (e.g. those drilled in September) will quickly become infected by septoria as the disease has more time to develop during the autumn’s favourable climatic conditions. Drilling date is therefore of importance, and of even greater consequence when drilling susceptible varieties (e.g. those with a rating of 5 and below). Pushing the drilling date back by three weeks or so into October is therefore advisable where possible as this will reduce the crop’s exposure to inoculum, without having too significant an effect on yield.
Fortunately, varieties with good resistance are starting to appear. While most of the winter wheat varieties on the AHDB Recommended List have scores between 4 and 6, there are now three varieties with a rating of 7. These can be used strategically to plan spray programmes and reduce the farm’s exposure to the disease in wet years, although they are still likely to need spraying.
Despite the arrival of these improved varieties, fungicide use remains essential. Spray applications must be timed accurately to protect key leaves, so that infections are unable to really take hold. This means using appropriate modes of action (stacked and sequenced usage of multi-sites, azole and SDHI chemistries) to provide a strong protective effect. For the more resistant varieties it may be possible to revise both the active component and dose rate of applications.