2000 Winter Wheat Variety Performance Results
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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 save Colorado wheat producers millions of dollars each year.
Adequate soil moisture conditions in the fall and mild winter temperatures led to good plant stands. Mild but dry winter conditions prevailed throughout much of the state. Favorable winter conditions led to large insect populations and losses were suffered from viral diseases transmitted by insects. Russian wheat aphid, Bird cherry-oat aphid, and Greenbug infestations were severe in SE Colorado; Greenbug and wheat curl mites were severe along the I-70 corridor; and Adams county had severe infestations of brown wheat mites. Barley yellow dwarf virus, transmitted by the Bird cherry-oat aphid and Greenbugs, were widespread from Baca to Kit Carson counties. Wheat streak mosaic virus and/or high plains disease was present in counties along the Kansas border. Very little leaf rust infection was observed in eastern Colorado although stripe rust (also known as yellow rust) infection was severe at the Genoa location and influenced yields. Following good rains in April, drought conditions dominated most of eastern Colorado in late spring through grain filling. Several late spring freeze events occurred but the worst, on May 13, reduced yields on large parts of eastern Colorado as well as compromising two of our variety trials.
Our dryland winter wheat variety trial was restructured in 1999 so that the low moisture (LMVT) and higher moisture trials (HMVT) of previous years were combined into a single uniform variety performance trial conducted at ten locations. There were 60 entries in the dryland trial, approximately half named varieties and half experimental lines. Six hybrids were entered by HybriTech-Monsanto, and Cargill-Goertzen entered five varieties. Two experimental lines from Kansas State University, and one new Nebraska variety were entered alongside common check varieties and experimental lines from the CSU breeding program. The CSU entries included two new white wheat lines, six herbicide-tolerant wheat lines, and experimental lines in their first, second, and third year of testing. Two irrigated variety trials were conducted at Rocky Ford and Haxtun. A randomized complete block field design with three replicates is used in all trials. Four or six, 12 inch-spaced rows, 46 feet long, are harvested from each plot. All dryland trials are seeded at 600,000 seeds/acre and the irrigated trials are planted at 900,000 seeds/acre.
The trial at Orchard was lost due to drought, disease, and freeze damage. The results of the Bennett trial were strongly influenced by the freeze and non-experimental errors led us to discard the results from the Sheridan Lake trial. This year's yields were lower than in the recent past - closer to long-term average yields - and several varieties that ranked high in the trial in the past (and risen to prominence in state acreage) did not rank as high this year. There were only modest total differences in average yield from the top-ranking variety to the lowest-ranking variety due to the multitude of different stresses experienced this year. Consequently, variety rank in 2000 is less reliable than average performance over multiple years as an indicator of expected future performance. Alliance and Trego were high yielding in both the high yielding environments of last year and the low yielding environments this year. The herbicide tolerant wheat lines (in TAM 110 background) were similar in yield to TAM 107 and Prairie Red.
This year's trials, under strong drought, heat, insect, and disease pressure were very valuable to the CSU wheat-breeding program to screen tough, new varieties for the future. The unified trial included 32 experimental lines (not included in this table), eight of which ranked among the top ten entries for highest average yield over locations, with the best yielding 114% of TAM107. The irrigated trial results illustrate how some public varieties are able to compete favorably with hybrids at high yield levels.
Variety planting suggestions, based on these trial results, are found in the revised "Decision Tree for Winter Wheat Variety Selection in Colorado." We encourage producers to spread the variety decision risk by planting more than one variety. The average performance over two or three years is a proven tool for yield performance evaluation but producers should be mindful of other varietal characteristics, like maturity, height, disease and insect resistances, quality parameters, and winterhardiness, that influence variety adaptation and performance.