Winter Wheat Variety Selection in Colorado for Fall 2005
Jerry Johnson and Scott Haley (August 2005)

Colorado’s unpredictable climate and the occurrence of various insect, disease, and weed pests of wheat make it difficult to predict the future performance of wheat varieties based upon their performance in previous trials. Nevertheless, in the tables below we provide the information wheat producers need to make the best possible decision under our variable circumstances.
Issues specific to variety selection in 2005:

Stripe rust- The most common question thus far this year has been whether we will have stripe rust next year. No one knows of course because it has caused damage in three of the last five years and in 2005 appeared weeks earlier than we had seen it in previous years. On the other hand, stripe rust epidemics require a favorable environment, a susceptible variety, and presence of stripe rust spores - all three of which coincided in 2005. Many of the available varieties are susceptible to some degree, some more than others. The favorable environment last year was promoted by early planting, good moisture and good late-fall growing conditions followed by a mild winter, prolific tillering and rapid early spring growth. These environmental conditions
are rare in Colorado and might not occur in 2006. The presence of spores is becoming more common in Colorado but clearly irrigated wheat production is at much greater risk than dryland wheat. White wheat- CSU personnel and the Colorado wheat
industry are convinced that white wheat is most promising future for wheat production and marketing in Colorado. The white wheat varieties, Avalanche and Trego, have performed well in the past few years but Trego must have been more affected by the heat and drought stress in May than Avalanche and some of the other varieties. We remain convinced that a white wheat variety should be high on the list for variety selection in 2005.

Russian wheat aphid- New forms (called “biotypes”) of RWA have evolved and rendered ineffective the resistance found
in all available RWA-resistant varieties. However, some of these varieties perform very well and should be considered for their yielding capability compared to other susceptible varieties. Hatcher, Bond CL, and Ankor are examples of RWA-resistant varieties that are high performance varieties for Colorado. CLEARFIELD* wheat- The variety Above is still a top performing variety but the new variety from CSU, Bond CL, has performed even better under dryland conditions over the past three years. It is important to remember that you can’t save seed of these varieties - even to plant on your own farm. The Plant Variety Protection Act and a U.S. Utility Patent protect them.

Selecting your variety-

Dryland wheat producers: Our first suggestion is to plant more than one variety in order to spread your risk. The yield table below is based on 3-Yr average performance in our trials, a method for variety comparison shown to be more reliable than single location or single year performance. Note that varieties are alphabetically ranked within a column, rather than ranked by average yields, to stress that differences among the varieties are not statistically significant. Bond CL and Hatcher are the two newcomers to the highest potential performance column and are the newest CSU releases. These two varieties will be included
in the new 2005/06 Collaborative On-Farm Test program. Relative maturity, measured by heading date, might be one way to spread risk related to drought, hail, or freeze damage. Susceptibility to stripe rust might also be a criterion for variety selection in 2005 although be careful not to base variety selection on stripe rust resistance alone. Under our normal low rainfall conditions, wheat streak mosaic virus might be a more consistent threat than stripe rust and worthy of consideration when selecting a variety. Plant height and coleoptile length might be important criteria for southeastern Colorado producers.

Irrigated wheat producers: Most irrigated producers plant a single variety and the most important criteria are yield and straw strength from the tables below. The Platte program has returned profit to many irrigated wheat producers through the incentive package, although some yield loss might be expected when stripe rust is a problem and is not effectively controlled with fungicides. The irrigated trials in Colorado have been very good the past three years and Jagalene, Yuma, Hatcher, and Ankor have performed very well even though Yuma and Jagalene are the only ones with above average straw strength. The newly released varieties Hatcher and Bond CL are welcome additions to our high yielding irrigated wheat varieties.