Winter wheat has progressed into the heading and flowering stages of development, while some of the earliest planted barley is about a week or two away from heading. As a reminder, there are two Fusarium head blight (FHB) risk tools that can be used to assess scab risk this year. One is available on the NDSU Small Grain Disease Forecasting website (https://www.ag.ndsu.edu/cropdisease), while a national model can be accessed at http://www.wheatscab.psu.edu/. The national model underwent revisions this past winter to make it more user-friendly (Figure 1). Currently, both the NDSU model and National FHB (Figure 2) model indicate low scab risk for ND.

A few questions have been received on what the latest rainfall events may do to scab risk. I like to call this rainfall an “activation” rain event. The fungal structures of the Fusarium fungus survive on host residue and need consecutive days of warm and humid weather (ie: what some areas experienced the past week) to mature and release spores. To put this in perspective, if a barley crop begins heading in two weeks, the recent weather events likely activated the fungal structures allowing spores to be available to infect barley spikes in the coming weeks. However, this will only occur if we continue to have prolonged periods of warm and wet weather, especially as the barley crop begins to head. A similar mentality can be used for the spring wheat crop as it approaches flowering later on this growing season.

Andrew Friskop

Extension Plant Pathology, Cereal Crops