2002 Colorado Winter Wheat
Variety Performance Trial Results

Performance trial results help Colorado wheat producers make better variety decisions.

Colorado State University conducts variety performance trials to obtain unbiased and reliable information for Colorado wheat producers to make better variety decisions. Good variety decisions can return millions of dollars to Colorado wheat producers.

Although precipitation in late summer and early fall 2001 was not abundant, trials were seeded timely and wheat stand establishment was excellent at all trial locations. The 2001/2002 winter temperatures were moderate but most trial locations suffered from lack of winter precipitation and snow cover. At each dryland trial location south of I-70, dry winter conditions combined with moderately cold temperatures caused significant winter injury and in some cases, total trial abandonment (e.g., Sheridan Lake, Cheyenne Wells). The winter drought carried through spring and early summer. Cold night temperatures in mid- and late-May led to widespread late spring freeze damage, especially in Northeast Colorado along Highway 14. As if conditions were not bad enough already, some areas were severely affected by hail, including the Genoa variety trial location. Continued widespread and severe drought conditions, combined with several periods of damaging high temperatures, led to earlier-than-normal harvest and extremely low yields. Though widespread throughout eastern Colorado, drought conditions were more prolonged and severe in southeastern Colorado.

In drought years like this, common dryland root rot often adversely affects yields-visible by sporadic 'white heads' in the field as was observed in many production fields and several trial locations. Insect pressure was low, but Russian wheat aphids could be found in some fields and may have caused slight yield reductions, especially along the Front Range. There was minimal yield loss to due wheat steak mosaic, high plains disease, or barley yellow dwarf virus. Stripe rust, which had been so severe in 2001, and leaf rust were present in relatively low levels in some irrigated fields after grain filling had commenced and probably had only small effects on yield.

Our dryland winter wheat variety trial (UVPT) is a single uniform variety performance trial comprised of 60 entries grown at 10 locations. Of the 60 entries in this trial, approximately half are named varieties and the other half are experimental lines. In addition to CSU varieties and experimental lines, the trial included public varieties from Nebraska, Oklahoma, Kansas, and Texas, and private varieties from Cargill-Goertzen and AgriPro. Due to winter injury, drought, spring freeze, and hail, only five of the ten trial locations were successfully harvested. Two of the five trials, Walsh and Lamar, were extremely low-yielding and highly variable preventing reliable differentiation among entries. Plot yields at Bennett, Akron, and Julesburg were low but reasonably high enough to be used for wheat variety selection purposes. Akron, the best dryland trial location all spring, experienced a damaging hail storm the night before harvest that reduced yields 15-25% in some entries. A randomized complete block field design with three replicates is used in all trials. Dryland trials were seeded at 600,000 seeds per acre and planted in 12 inch-spaced rows, except Julesburg that was seeded in 9 inch-spaced rows.

Irrigated variety trials were conducted at Rocky Ford, Haxtun, and Fort Collins. The irrigated trials are seeded 1.2 million seeds per acre. The Haxtun and Fort Collins trials were grown under sprinkler irrigation and the Rocky Ford trial was furrow-irrigated. Rocky Ford and Haxtun trials provided excellent results, but the Fort Collins trial suffered significantly from the spring freeze of May 9 and a damaging hail storm two weeks before harvest that reduced yields 30-70% in some entries.

The authors wish to make special note of two wheat improvement programs that will affect variety selection for the coming year: CLEARFIELD* wheat and Hard White Wheat (HWW) varieties.

CLEARFIELD* is a unique production system comprised of herbicide-tolerant wheat varieties, Beyond™ herbicide to manage problematic weed species, and a stewardship agreement with growers to ensure the use of best management practices for system sustainability. The first publicly-developed CLEARFIELD* winter wheat varieties to be released in the U.S., 'Above' (from Colorado State University and marketed by the Colorado Wheat Research Foundation) and 'AP502 CL' (marketed by AgriPro Seeds, Berthoud, CO) are tolerant to Beyond™ herbicide for use in the CLEARFIELD* wheat production system.

Above is an awned, white-chaffed, early maturing, semi dwarf hard red winter wheat. In 2000 and 2001 Colorado variety trials, Above yielded more than Akron, TAM 107, and TAM 110. Average test weight for Above in these trials was less than TAM 107, but more than TAM 110. Above matures 3.5 days earlier than Akron and about 1.5 days later than TAM 107. Above is short, similar to TAM 107, and has similarly good straw strength. Above is resistant to stem rust, susceptible to leaf rust, and moderately susceptible to both wheat streak mosaic virus and barley yellow dwarf virus. Above is resistant to greenbug, and susceptible to the Great Plains biotype of Hessian fly and Russian wheat aphid.

AP502 CL is an awned, red-chaffed, early maturing, semi dwarf hard red winter wheat. AP502 CL is very similar to Above in many respects, yet has shown lower average grain yield and test weight in Colorado variety trials. AgriPro Wheat intends to market AP502 CL in areas of the Great Plains where their distribution and marketing system is strongest.

More information on the CLEARFIELD* wheat production system can be obtained at the following websites:

(CLEARFIELD Wheat Fact Sheet as html)
(CLEARFIELD Wheat Fact Sheet as PDF)
(BASF's CLEARFIELD website with their technical bulletin and the stewardship guide)

White Wheat varieties
Development of hard white winter wheat (HWW) varieties has been a top breeding priority in the Great Plains for over 10 years. Enhanced preference for HWW over hard red winter wheat (HRW) in most export markets is the predominant factor driving the strong interest in increasing HWW acreage in the Great Plains.

In the 2002 US Farm Bill, a three-year market incentive program was established to foster development of US HWW production and markets. With the recent development of HWW varieties well adapted for production in Colorado, wheat producers now have an excellent opportunity to participate in a concerted, market-expansion effort. The most promising of these HWW varieties for production in Colorado include the following:

Trego is medium height, medium-late semi dwarf released by the Kansas State University program at Hays, KS, in 1999. Trego has shown both very high yield and test weight in CSU dryland trials and throughout the High Plains region. Trego has inadequate straw strength for irrigated production conditions. Trego is susceptible to Russian wheat aphid.

Avalanche is a medium height, medium maturing semi dwarf released by Colorado State University in 2001. Yields of Avalanche in CSU dryland variety trials have been slightly less than Trego (though equivalent to Akron) with similarly high test weight. Avalanche has performed better than average in experimental bread baking tests but, like Trego, is not suitable for Asian noodle production. Avalanche is susceptible to Russian wheat aphid.

Lakin is an awned, white-chaffed, medium maturing, semi dwarf released by the KSU-Hays program in 2000. Grain yields of Lakin in CSU dryland variety trials have been slightly less than Trego and Avalanche, but its straw strength may allow successful irrigated production at moderately-high yield levels. Lakin possesses both good bread baking and good Asian noodle quality characteristics. Lakin is susceptible to Russian wheat aphid.

Platte is an awned, white-chaffed, medium maturing, semi dwarf released by AgriPro in 1995 and marketed under an exclusive contract arrangement with ConAgra Flour Milling. Platte has shown excellent straw strength as required for high-input, irrigated production conditions. Platte is very susceptible to stripe rust, a rare problem in Colorado except under very high moisture or irrigated conditions. Platte is susceptible to Russian wheat aphid.

More information concerning hard white wheat may be obtained at the following website: http://www.awwpa.com (website for the American White Wheat Producers Association)

The authors encourage wheat producers to make use of the "Decision Tree for Winter Wheat Variety Selection in Colorado" because it reflects our synthesis of data and field observations over years and locations. Because this year provided so little information to aid variety selection, we think growers should rely on variety performance data acquired in more normal years. Unfortunately, some varieties were being tested for the first time in 2002 and there is just too little information to make sound recommendations. Producers are also encouraged to spread the variety decision risk by planting two or more varieties. The average performance over two or three years is a proven tool for yield performance evaluation but producers should be mindful of other variety characteristics, like maturity, height, disease and insect resistance, quality characteristics, and winter hardiness, that influence variety adaptation, performance, and marketing options.