By Pierce Paul
According to the FHB forecasting system, the risk for head scab continues to be low across the state of Ohio, for wheat flowering (or barley heading) today, May 18. In spite of the wet weather we have had, it has been very cold over the last week to 10 days. Cold temperatures between heading and flowering usually reduce the risk for scab, as the disease develops best under warm, wet, or humid conditions. However, you must continue to be vigilant as the crop in the northern half of the state approach heading and anthesis. If it continues to rain and stays wet and humid over the next few weeks, the risk for scab and vomitoxin will increase as the temperature increases. Be prepared to treat fields with Prosaro, Caramba, or Miravis Ace. Click on this link for more details on fungicide application for head scab control: https://agcrops.osu.edu/newsletter/corn-newsletter/2020-13/managing-head-scab-fungicides-qa
While scab is not yet a concern, either because it is too early, or because it has been too cold, current conditions do favor leaf diseases such as Septoria leaf spot and powdery mildew. Both have been reported on the lower leaves of susceptible varieties, and will continue to spread up the plant if it stays cool and wet. In addition, persistent rainfall and warmer temperatures over the next few weeks will not only increase the risk for scab, but will also increase the spread and severity of other diseases such Stagonospora leaf and glume blotch. All of these diseases can reduce grain yield and quality, if flag leaves and heads are severely damaged before grain fill is complete. Continue to walk fields and look for leaf diseases. If the variety is susceptible, an early fungicide application may be needed to keep leaf diseases in check. Otherwise, an application (of Prosaro, Caramba or Miravis Ace) at or shortly after flowering (at or shortly after heading in barley) for scab control will also provide effective control of leaf diseases.
Source : osu.edu