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The Fusarium Head Blight Prediction Center is again up and running for the 2010 wheat growing season. I will be providing commentary on this site for Wisconsin similar to the previous growing seasons and this commentary often focuses on observations of all diseases we have noted around the state, and more importantly the current range of growth stages we have observed. Also, the U.S. Wheat and Barley Scab Initiative will be providing resources to help in communicating the current risk and situation across the wheat growing region. Some additional resources that may be of help as you access this site as well as determine the need for foliar fungicides for control of Fusarium head scab include:

1) Understanding the Fusarium Head Blight Prediction Center

2) Check Your Wheat Closely

Feel free to contact us with any questions and we will provide further updates as the conditions warrant.

Winter wheat in Wisconsin is looking very good across the majority of our field trials. In some of these trials, we are already at the Feekes 4 (Zadoks 30, pseudostem erection) growth stage. This week, it was noted that there is some evidence of powdery mildew (see photos below courtesy of John Gaska) in some of these trials. This is an important period for some early-season management decisions (not just for foliar fungicides also). Specifically for decisions for disease management, it really starts with knowledge of the relative susceptibility of your wheat variety against powdery mildew. With that knowledge, a second step is to then determine how severe and where in the wheat canopy are symptoms of powdery mildew being noted. At Feekes 4-5, the recommendation for the use of a foliar fungicide is based on the appearance of symptoms of powdery mildew on the newest (i.e., upper) leaf. Scouting by examining approximately 100 leaves in a field from different locations. Assess the severity for each leaf by counting the number of powdery mildew pustules. If the average number of pustules is 10 or greater, this may indicate the need for use of a foliar fungicide. In most years, we often see symptoms of powdery mildew in the wheat canopy, but typically only in the lower canopy due to the microclimate and varietal differences. Disease management decisions at these earlier growth stages need to take into account the assessment of the most appropriate leaf material that may impact the flag leaf later in the growing season.

Photos from Arlington, WI (Courtesy of John Gaska, Dept. Agronomy). Notice that the primary location of symptoms are in the lower canopy. As discussed earlier, guidelines for the use of foliar fungicides are based on examination of the uppermost leaf.

Late soybean and field corn harvest caused a significant drop in WI winter wheat acres in 2010. Many growers, including myself, still decided to move forward with late winter wheat plantings. To answer late-planted wheat questions we published the following article on November 23rd 2009.

Late Planted Winter Wheat: Growing Slowly But Surely

As with many growers we had a difficult time getting all of our winter wheat planted in the “Optimal” planting date window in 2009. A significant number of winter wheat acres across Wisconsin were planted under the full knowledge of reduced crop insurance coverage as well as reduced yield. Given that the 10-day weather outlook calls for reduced temperatures as well as potential flurries I was interested in the “state” of our November 13th planted winter wheat in Janesville WI. In Image 1. we see that the radicle, seminal roots, and coleoptile have all emerged. In wheat the radicle and seminal roots will be the first structures to appear. Only after the seminal roots and radicle begin to imbibe water will the coleoptile begin to elongate.

For those winter wheat acres that were planted in the last few days remember that winter wheat will vernalize once the radicle emerges from the seed as fall growth will continue as temperatures fall to zero. Literature referenced: R.J. Cook and R.J. V

Today (3/18/10) I revisited our Janesville winter wheat site that was planted on Friday November 13th 2009. The wheat crop has emerged relatively uniformly and appears to have made it through the winter with very little crop loss (Image 2).

At this juncture the most critical decision facing growers is “Do I invest money into this crop?” Though I have no data that directly mimics this years situation we can use our 2009 planting date study as a starting point. In Figure 1 below we see that our late planted wheat (planted Oct 17th) suffered a 28% yield loss when compared to our early planted wheat (planted Sept 18th). Though our 2010 crop was planted 27 days later than the 2009 data what we can guesstimate is that your late planted wheat will likely yield at least 28% less than normal production levels. So your decision is “Can I still make money off of a wheat crop that is expected to yield ~30% less than normal production levels.” If the answer to that question is yes than it is critical to get across that wheat as quickly as possible with an early N application to stimulate tiller formation. It will also be important to scout early and often as weeds will likely be a greater issue in 2010 than in “normal” years.

We have recently completed the development of a Winter Wheat Variety by Disease Database (version 1.0) based on results from the 2009 Winter Wheat Performance Trials in Wisconsin. The goal of this database is to assist growers in variety selection, especially regarding how these varieties compared against different diseases commonly seen in Wisconsin. This database will continue to be updated annually.

Within this database, varieties can be sorted based on their combination of disease response and yield performance. At each location, every variety has been given a score from 1-4 for each disease:

– 1 = high yield, low disease
– 2 = high yield, high disease
– 3 = low yield, low disease
– 4 = low yield, high disease

These scores are based on rankings of yield and disease response. Each variety was ranked as either high yield (top 50% of varieties for that location) or low yield (bottom 50% of varieties for that location) and low disease (top 50% of varieties for that location) or high disease (bottom 50% of varieties for that location). A word of caution…the use of “high” and “low” in this context are relative terms. These are meant to describe a variety in the top or bottom half of varieties within a given location. These designations should be interpreted carefully; if the overall level of a disease was low at a location, then even the variety ranked worst for that disease might not have had very high levels of disease.

Before using the database, read “Using the Excel Database: Background and Instructions,” which describes the presentation of the data and the use of the “sort” function in Excel.

After looking at the instruction file, open the Winter Wheat Variety-Disease Database. The “sort” feature described in the instructions can be used to look at which varieties perform best against certain diseases, or to look at the performance of specific varieties.

Questions about how to use the database can be addressed to either Paul (Email: esker@wisc.edu) or Karen Lackermann (lackermann@wisc.edu).