Planning out a disease management strategy in cereal crops needs to start earlier than usual this season. Programmes can be adjusted as the season goes on but setting out the basic framework makes it possible to work in a diversity of chemistry to minimise resistance risks and cover the main diseases and timings. The warmer than average winter and the well-established state of crops means fairly ideal disease conditions. With very few frost days there has been little to knock back early disease and recent snow cover creates an almost perfect environment for diseases like yellow rust.
Decision making in years where crops are thin and backward and input costs are high can be hard, but this year with winter crops showing good potential and some early disease in crops then some careful disease management is justified. Once a programme is drafted, fungicide inputs can be adjusted throughout the season in response to disease levels, weather and the efficacy of previous sprays, for example by varying the dose. Keeping the same actives keeps diversity of actives in the programme, avoids over relying on one particular active and can help manage resistance risk.
In wheat azole fungicides are still the backbone of yellow rust protection and are fundamental to managing septoria. Alternating and mixing chemistry brings broader spectrum disease control and gives some protection against resistance, and including azoles in mix with either an SDHI or the newer active QiI (in makes more diversity possible than before. It is possible to switch between azoles in wheat programmes and alternate between mefentrifluconazole (in Revystar XE) and prothioconazole (in products like Ascra Xpro) at the main T1 and T2 timings.
Aim to balance the effective dose of azole plus SDHI or azole plus QiI mixes and, if raising or lowering the dose, doing it in a balanced way avoids leaving one component exposed. The multisite folpet is at lower resistance risk and can support programmes – and including the active ingredient folpet adds to septoria management in SRUC trials.
In winter barley, T1 is the most responsive timing so where the most effective of the SDHI and azole chemistry like Revystar XE or Ascra Xpro can be used. Early clean-ups may be needed to manage overwintering rhynchosporium and there is mildew already very evident at SRUC trial sites. Watch too for net blotch which has been more common in the last few seasons.
Fiona Burnett, SRUC for the Farm Advisory Service
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