Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu
Now is a good time to sign up for the Fusarium Head Blight Prediction Center (http://www.wheatscab.psu.edu/). This is a tool that correctly predicts severe head blight epidemics 80% of the time. If you recall, we integrated the DEOS stations into the FHB model last season, giving Delaware and Eastern Shore Maryland additional model precision (you can see this by clicking the Agnet box in the legend-Figure 1). This tool has saved wheat producers in the United States over $15 million in the last few years, and I recommend becoming familiar with the system. If you are on the fence about making a costly fungicide application, the model can give you another piece of information that can help you with this decision. If you recall, last year the model, for the most part, suggested that the head blight fungicide should not be applied. With very few exceptions in a field here and there, the model was correct. In 2013, the model told us to spray: we all remember what happened that season. The model can be used to take a peek 2-3 days into the future as well, based off of the previous 7-10 days of weather.
Figure 1. A screen shot of the Wheat Scab Prediction center website showing new weather stations for use in helping with local risk prediction (recall there used to be only three in Delaware).
The model has been tweaked to better predict outbreaks under cooler conditions and other situations where the model was underperforming in the past. You will also notice that you can change your forecast based on the Fusarium head blight resistance level of the wheat you planted. Most of our varieties are susceptible; I would not consider any commonly planted varieties to be “Very Susceptible.” I would advise only considering your variety moderately resistant if, after looking at the Virginia Tech Misted Nursery data (2-3 year averages), the DON (vomitoxin) levels are reduced 45% or more compared to a susceptible check such as Dynagro Shirley or Pioneer 25R40. Do not look at severity or incidence data — it is DON, particularly that which accumulates in healthy, plump kernels, which concerns us the most. The VT misted nursery data can be found here: https://pubs.ext.vt.edu/CSES/CSES-129/smgrains15sect5.pdf. Reliable scab resistance data can only be generated from misted nurseries. Field based observations for rating varieties for head scab resistance are unreliable, misleading, and not useful.
Once you have signed up don’t forget to ensure that you receive email updates on regional commentary. I will update you on the overall situation, etc. In addition, remember that the model is generating the map based on data collected from hundreds of different sources, so this takes time. As a result, the most up to date forecast for the day will not be available until around lunch time. If you view the map in the morning, you are looking at the previous day’s forecast. Again, remember that this is a tool that should be used in addition to local weather, your intuition, and other sources to help you make profitable fungicide decisions in wheat in 2016.