August 10, 2007

Every year there seem to be new challenges for the wheat crop. We have had several years of drought where wheat was about the only crop that produced grain. Then it began to look like much of the state was getting better rainfall with the new crop coming through the winter quite well. This was followed by an April freeze, with the most advanced wheat fields suffering the most damage. Even then, wheat showed its ability to survive as later tillers made a reasonable crop.

As the season progressed, rains continued in eastern Nebraska, but were less prevalent in western Nebraska. Unfortunately, the very rains that bolstered the crop early season encouraged a multitude of diseases. Rainfall further south also raised our humidity, further encouraging diseases. These diseases attacked the stem, leaves, and head and included powdery mildew, Septoria leaf and glume blotch, tan spot, leaf rust, stripe rust, scab (Fusarium head blight), common root rot, take-all, black chaff, barley yellow dwarf virus and wheat streak mosaic virus.

So how do we make use of these lessons in preparing for the next wheat crop? Since we haven't learned to control the weather, our next best plan is to choose the best varieties and prepare our fields in the best manner. 

1. Select varieties with ample winter hardiness. This includes varieties that can tolerate cold temperatures and don't start greening up too early in the spring. Most varieties grown in Nebraska have adequate winter hardiness because the tender ones are quickly eliminated.

    

2. Use varieties with good disease resistance (see box). This is a changing landscape, requiring yearly research to assess traits and variety trials. Varieties which had good resistance two years ago now may be susceptible due to changing genetics in the disease causing organisms. Remember that the more popular a variety is (especially south of Nebraska), the more pressure is exerted by diseases. This is because planting the same variety over a large area increases the chance of disease causing organisms to mutate or change their genetics and overcome the disease resistance in that variety.

    

3. Choose varieties which meet quality standards to protect Nebraska's reputation as a producer of high quality wheat. Most seed offered for sale meets those standards.

    

4. Plant high quality seed. This includes seed that is of known varietal purity, free of weeds and disease, with good germination, and which has been treated to prevent problems after planting.

    

5. Select varieties that can withstand dry conditions but are able to produce well when conditions improve. Since needs and conditions change from one part of the state to another, it's important to review variety performance over many years and locations.

After you determine the disease resistance and winter hardiness level needed for your farm, you can then use a number of resources available to identify the varieties that best fit your situation. The University of Nebraska tests wheat varieties across the state and makes the data available in publications available from your local Extension office and on several Web sites:

Wheat Variety Testing Web site at http://varietytest.unl.edu/winterwheat/2007.html
UNL Wheat Varieties Virtual Tour at http://www.panhandle.unl.edu/wheat/index.html
wheat variety selection tool at http://citnews.unl.edu/winter_wheat_tool/index.shtml.
You also canobtain information from seed dealers about the varieties they recommend and sell.

Lenis Nelson
Extension Crop Variety Specialist