Posted 28 May 2015. PMN Crop News.
Fusarium Head Blight Update
Local conditions dictate the risk for fusarium head blight. Be familiar with the indicators for elevated risk and respond accordingly
Source: Penn State University Press Release. agsci.psu.edu
University Park, Pennsylvania (May 19, 2015)--Wheat in the southern regions of Pennsylvania is now heading, with early varieties flowering. Fusarium head blight (a.k.a. head scab) is a disease of wheat and barley that can lead to the production of toxins in grains. The fungus that causes this disease enters through the flowers and infects the developing grain. Warm, humid environmental conditions at wheat or barley flowering favor the development of this disease.
Most areas of Pennsylvania are now at a “Low”risk for the development of scab in wheat and barley that would start to flower in the next week, except for the most susceptible varieties. While most areas of southern PA have been quite dry, isolated showers may have kept certain areas more humid. Use your judgement based on your experience and your local conditions. Be prepared to spray a fungicide on fields that are at medium to high risk at flowering. Remember, sprays applied prior to flowering will notprovide significant suppression of scab or toxin production, however, a spray up to a week after the beginning of flowering can offer good disease and toxin reduction.
Caramba or Prosaro are effective on scab and give control of most leaf diseases and glume blotch. They do not need to be tank mixed with another product to control these diseases. If either these products is unavailable, Proline and Folicur (which together provide the same chemicals as Prosaro) may be tank mixed at a rate of 3 + 3 fl oz/A. Spray nozzles should be angled at 30° down from horizontal, toward the grain heads, using forward- and backward mounted nozzles or nozzles with a two directional spray, such as Twinjet nozzles.
Once wheat begins flowering, there is about a 5-6 day window to apply a fungicide. The labels state the last stage of application is mid-flower and there is a 30-day to harvest restriction. Do not use any of the strobilurins (Quadris, Headline), or strobilurin/triazole (Twinline, Quilt, Stratego) combination products at flowering or later. There is evidence that they may cause an increase in mycotoxin production.
At this point in the season, the only way to reduce the scab problem is to spray. But in general, do not rely solely on fungicides, as they will provide at most a 50–60% reduction in scab severity and vomitoxin. Choose resistant wheat varieties, and time sprays properly to achieve greater control.
Keeping an eye on the FHB Risk Assessment Tool will become critical for those farmers who have wheat beginning to flower in the next few weeks. This forecasting site is an online model that helps us predict infection risk levels everywhere in the state. It has been improved over the last year to include some new features and better accuracy. Visit it at your convenience, or sign up to have updates e-mailed or texted directly to you.