For wheat flowering today, May 27, the risk of scab is low, according to the prediction took. Several fields across south-central Ohio reached anthesis over the weekend, and since conditions were fairly dry in most of those areas, the risk tool also predicted low scab risk for those fields. However, things may change for fields in the Northern half of the state that are likely to reach anthesis later this week. The weather forecast is for wetter condition, with between 40 and 60% chance of precipitation on two of the next five days in some locations. Moreover, conditions have been humid; both rainfall and high humidity favor scab development and vomitoxin contamination of the grain.
Continue to use the prediction tool to assess the risk for scab over the next 7 to 10 days, and be prepared to apply Prosaro or Caramba, if moderate to high risk is predicted at the time the crop reaches the flowering growth stage. Remember, these fungicides are most effective against scab and vomitoxin when applied at flowering. However, if you are unable to treat your field at the flowering stage, you can still get good scab and vomotoxin control if you apply the fungicide up to six days after flowering. Later applications may be less effective, and most importantly, may be off label, since the pre-harvest interval for both Caramba and Prosaro is 30 days. On average, wheat in Ohio is usually harvested between 40 and 45 days after anthesis.
--Pierce Paul, Extension Plant Pathologist, Ohio State University
For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu
For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to http://www.scabusa.org