By Pierce Paul, Ohio State University Extension
It is still too early to apply a fungicide to manage head scab. Use the scab forecast system (http://www.wheatscab.psu.edu/) to monitor concerns. If you plan to spray for head scab, Prosaro or Caramba may be your fungicide of choice. The new fungicide, Miravis Ace, which seems to be just as effective as Prosaro and Caramba based on a limited number of trials, may not yet be widely available. STAY AWAY from the strobilurins when it comes to head scab management. These fungicides tend to increase rather than reduce vomitoxin contamination.
I know that the idea of “protecting the crop” with a “preventative treatment” seems to suggest that the fungicide has to be applied before the crop reaches the critical growth stage — flowering in the case of wheat. But results from more than 20 years of scab research show that you are better off applying a few days “late” rather than a few days “early.” Remember, with head scab you are also trying to reduce grain contamination with vomitoxin, and fungicides are certainly more effective against this toxin when applied at or 4 to 6 days after flowering for wheat.