2001 Colorado Winter Wheat Variety Performance Trials

Trial results provide information for making good 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. Inadequate soil moisture conditions throughout much of eastern Colorado in the fall of 2000, especially in southeast Colorado, led to late planting or planting into dry soil. Cooler than normal temperatures in October and November resulted in inconsistent stand establishment and slow fall growth. Significant portions of fall-planted acreage did not emerge until early spring following mild winter temperatures and good winter moisture. Early spring growth was good at many locations but was followed by late spring drought. Cloudy spring conditions resulted in below normal growing degree-days in many locations and wheat that had been slow to emerge in the fall, or did not emerge until early spring, did not tiller as profusely as usual. High yield potential for irrigated winter wheat was adversely affected by sub-optimal fall and spring growing degree-days. Cold night temperatures in mid-May led to widespread late spring freeze damage, although less severe this year than in 2000. Prolonged high temperatures in June affected grain filling and reduced yields, especially in locations already stricken with drought. Heavy June infestations of stripe rust also led to widespread damage, especially in northeast Colorado. Historically, stripe rust occurrence in Colorado has been very rare, only once in approximately 20 years according to Bill Brown, CSU pathologist. Initial estimations of expected yield loss due to stripe rust were minimal due to the late stage of infection followed by long periods of high temperatures and low moisture. Later evidence suggests that yield losses were greater than expected, as much as 25% in the irrigated wheat trial at Haxtun. Dryland trial locations most severely affected by stripe rust were Julesburg, Akron, and Walsh. Moderate stripe rust infection was observed at Briggsdale and Genoa, the latter of which was the only trial in 2000 with stripe rust. Insect pressure was low to non-existent in 2001. Consequently there was only minimal yield loss to due wheat steak mosaic, high plains disease, or barley yellow dwarf disease. Our dryland winter wheat variety trial, restructured in 1999, is a single uniform variety performance trial conducted at 10 locations. Yields were obtained from eight of the ten locations as hail destroyed the Bennett trial in May and the Sheridan Lake trial, which was in an area dominated by spring emergence, was not harvested due to severe wind erosion in early spring. Of the 60 entries in this trial, approximately half are named varieties and the other half are experimental lines. In addition to CSU varieties, named and experimental lines, the trial included public varieties from Nebraska, Oklahoma, and Kansas, and private varieties from Cargill-Goertzen and General Mills. Irrigated variety trials were conducted at Rocky Ford, Haxtun, and Fort Collins. The Rocky Ford trial, that looked so good all spring, was destroyed by hail in early June. A randomized complete block field design with three replicates is used in all trials. All dryland trials were seeded at 600,000 seeds per acre and planted in six, 12 inch-spaced rows, 46 feet long. The irrigated trials are seeded 1.2 million seeds per acre. The Haxtun irrigated trial was grown under circle sprinkler irrigation with plots seeded in 7 inch-spaced rows, 6’ wide and 26 feet long. The Fort Collins, furrow-irrigated, trial was planted in 7 inch-spaced rows on 30 inch beds and plots were 26 feet long. 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 resistance, quality characteristics, and winter hardiness, that influence variety adaptation, performance, and marketing options. Complete variety descriptions and the full complement of trial results can be viewed on the web at: http://www.colostate.edu/Depts/SoilCrop/extension/CropVar/wheat1.html. by Jerry Johnson and Scott Haley Crops Testing and Wheat Breeder Dept. Soil and Crop Sciences Colorado State University To top of page

Wheat Stripe Rust In Colorado - What Happened?

Weather patterns contributed to arrival of fungus in Colorado.

The same rains that saved much of the state’s wheat in 2001 also brought the wheat stripe rust disease. Wheat stripe rust is a fungus that attacked the leaves and in some instances the glumes of wheat. It developed in the unexpectedly cool and humid conditions that prevailed in the last of May and early June. We have never seen such a problem with stripe rust on the plains in wheat, although it has occasionally been found at insignificant levels. Early in the season it was seen developing in Texas, then Oklahoma and then in Kansas where it is equally rare. Normally it would have been stopped by increasingly high temperatures and dryness, but not this year. In mid May, there were no prevalent diseases and the warm temperature had stopped the stripe rust in Kansas while wheat was in the boot in Colorado. In late May and the first week of June, stripe rust took off again and moved into Colorado wheat during flowering. It eventually moved all the way to the Front Range. Irrigated wheat, such as Platte, was hard hit. Increased nitrogen and high plant populations in irrigated wheat exacerbated the severity of the stripe rust infestations. Questions about stripe rust have been asked by researchers and growers alike. Bob Bowden in Kansas has addressed these in detail and I am basically quoting his questions and some thoughts here as well as my own experience over 25 years with a similar stripe rust of barley Where did it come from? The stripe rust fungus does not survive in the US. Normal it survives on green host tissue in Mexico and sometimes Texas. This year it was first noted in mid-March in the area around Uvalde, Texas. Very strong southerly winds traveling directly from the Gulf Coast to Kansas probably brought the fungus spores into that area much earlier than would be normal. How did it develop in Colorado? Wheat stripe rust was first reported in southern Kansas on May 2 at Hutchinson. During the week of May 7, reports of stripe rust were coming from between Dodge City and McPherson and from south of Highway 56 to the Oklahoma border. Unusually warm weather from May 14-17 was expected to inhibit further development of the epidemic and Dr. Bowden reported rust lesions on most varieties began to dry. On May 19, a cool, wet period began which lasted three weeks and the fungus took off again. By May 29, it was in the Goodland, KS area. This second burst of spores got to Colorado and caused our initial infections. Have we had this problem before? No, we have seen traces of stripe rust on occasion but never at the level seen this year. Dr. Bowden noted that it is pretty much the same in Kansas but that last year there was a small outbreak of stripe rust in central Kansas that caused an estimated loss of 0.05%. When he examined the official USDA rust loss estimates from 1918 to 1976, there was no data for stripe rust losses in Kansas. However, records indicate that in 1957 and 1958 stripe rust epidemics occurred in the Southern Plains that pretty much matched the situation in 2000 and 2001. Both 1957 and 1958 were unusually cool and wet across the Southern Plains. Would fungicides have worked? Yes, foliar fungicides would have worked if applied early enough. Excellent control can be obtained with Tilt if applied before disease severity on the lower leaves reaches 5% at the late boot stage. My work with barley stripe rust in South America also supports Dr. Bowden’s observations. However, Tilt can not be used beyond boot in Colorado and we had no rust at boot. At that point with wheat at less than $3 and Tilt at about $12/acre it is unlikely anyone would have sprayed. The rust hit us at flowering and the only alternative was to use Quadris, the new strobilurin fungicide from Syngentia. Quadris would have cost $24-28/acre and even more critical, has a 45-day pre-harvest interval. So effectively we were out of luck. Will stripe rust be a problem next year again? It is unlikely that we will see this kind of a problem again for another long time. If the kind of weather that we saw this spring occurs again and the inoculum gets into Kansas early enough then the possibility does exist. Barley stripe rust problems in the early 1900s, can be attributed to four conditions (really outside of Colorado): unusually cool, wet weather in Texas helped develop stripe rust early on, strong southerly winds transported a heavy spore shower to Kansas in mid-April, unusually cool wet weather in Kansas in May allowed the rust to develop to the levels that then served as the inoculum for eastern Colorado, and unusually cool, wet weather developed in late May and early June on the High Plains that allowed the fungus to develop once it arrived. It seems unlikely that we will get all this together again next year. Our best approach is still to follow the development of disease development in Kansas and base our action on what develops there. Should we not use susceptible varieties next year? Even though is unlikely we will see this kind of situation again it is always a good idea to use a mix of varieties in your fields. There is always the potential for different problems to develop. The major problem in most years is more likely to be Russian wheat aphid. This year we saw susceptibility to stripe rust but we want to avoid over compensating for stripe rust and getting hit hard with another kind of problem. by William Brown Extension Plant Pathologist Dept. of Bioagricultural Sciences and Pest Management Colorado State University To top of page

Dryland Wheat Strips For Forage And Grain Yield At Walsh, 1999-2001

TAM 110 is a good multi-purpose variety choice for Southeastern Colorado.

The purpose of this trial was to determine which wheat varieties are best suited for forage and grain production in Southeastern Colorado. Fifteen or sixteen winter wheat varieties were planted at Walsh from 1998 to 2000 using 45 lb/a seed in 20 ft. by 1110 ft. strips with two replications. In all years, the strips were fertilized at or above recommended rates from soil test results. Weeds were controlled using Ally or a combination of Ally and 2 4-D herbicides. Forage samples (two samples per plot, 2 ft. by 2.5 ft.) were taken at jointing (late March). Fresh forage samples were weighed, oven-dried, and reported as dry weight at 15% moisture content. Plots were harvested with a self-propelled combine and weighed in a digital weigh cart. Grain yields were corrected to 12% moisture content. Results 1999 - Jagger produced the highest forage yield and Alliance produced the highest grain yield (Table 1). Jagger was the best overall variety for grain and forage yields. There was a minor infestation of Russian Wheat Aphid (RWA). 2000 - Jagger produced the highest forage yield at jointing while Ike produced the highest grain yield (Table 2). The best variety for overall forage and grain yield was TAM 110. There was a minor infestation of RWA, but a seve re infestation of greenbug and other aphids. Barley Yellow Dwarf, a viral disease vectored by several aphid species (but not by RWA), impacted this study and Ike appeared to be more tolerant of the BYD virus than any of the other varieties. 2001 - Prowers produced the highest forage yield while Trego produced the highest grain yield (Table 3). Prowers appears to be the best overall variety for grain and forage yield for 2001. Late planting and low heat units in the fall of 2000 and spring of 2001 combined with drought conditions in the spring led to lower than normal plant size and forage yields. 3-Year Summary - Akron had the highest 3 year average forage yields while Alliance yielded the most grain (Table 4). This trial indicates that TAM 110 is probably the best variety choice for overall forage and grain yield in Southeastern Colorado. by Kevin Larson, Dennis Thompson, Deborah Harn, Calvin Thompson Research Scientist, Technician III, Research Assoicate, and assistant Plainsman Research Center To top of page

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Websites

http://www.colostate.edu/Depts/SoilCrop/extension/CropVar/index.html CSU's Crops Testing page for Wheat Variety Performance Trial Results. http://www.ext.colostate.edu/pubs/crops/pubcrop.html CSU's Cooperative Extension publications relevant to crops and soils. http://www.ksu.edu/kscpt/ Kansas State Universisty's Crop Performance page with Variety Trial Results. http://www.hpj.com High Plains Journal on the net, requires Internet Explorer 5 or Netscape Navigator 5 for viewing. http://www.nal.usda.gov/ The Nationals Agricultural Library (NAL), part of the Agricultural Research Service of the U.S. Department of Agriculture, is one of four national Libraries in the United States. http://www.uidaho.edu/aberdeen/cereals/index.html University of Idaho, Aberdeen Extension Cereals Propgram: "The Cereals Information Source." http://varietytest.unl.edu/whttst/2001/index.htm University of Nebraska Wheat Variety Testing results. http://www.ianr.unl.edu/pubs/FieldCrops/ University of Nebraska's famous Nebsheets for Crop Production. Excellent information. http://www.colostate.edu/programs/lifesciences/TransgenicCrops/ Information about transgenic crops including history, explanations of the process, figures on crops in use, and a quiz to test your knowlede about the issue of transgenic crops. http://triticum.agsci.colostate.edu/vpt.html Colorado Winter Wheat Variety Performance Database.

Agronomy news is a publication of Cooperative Extension, Department of Soil & Crop Sciences, Colorado State University, Fort Collins, Colorado. Web Site: http://www.colostate.edu/Depts/SoilCrop/extension/Newsletters/news.html The information in this newsletter is not copyrighted and may be distributed freely. Please give the original author the appropriate credit for their work. Direct questions and comments to: Debbie Fields Phone: 970-491-6201 Fax: 970-491-2758 E-Mail: dfields@lamar.colostate.edu

Extension staff members are: Troy Bauder, Water Quality Mark Brick, Bean Production Betsy Buffington, Pesticides Pat Byrne, Biotechnology Jessica Davis, Soils Jerry Johnson, Variety Testing Raj Khosla, Precision Farming Sandra McDonald, Pesticides Clark Oman, Minor Crop Pesticides James Self, Soil, Water & Plant Testing Gil Waibel, Colorado Seed Growers Reagan Waskom, Water Quality

	Colorado State University, U.S. Department of Agriculture, and Colorado counties cooperating. Cooperative Extension programs are available to all without discrimination. The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by Colorado State University Cooperative Extension is implied.