Selecting Your ’03 Hybrids
The 2002 growing season served as a good reminder that yield is just one of many variables to consider when comparing and choosing a sunflower hybrid. Indeed, maturity, standability, dry-down, pest and disease tolerance were all critical yield factors.
“Just because a hybrid is the top yielder in plot trials doesn’t necessarily mean it will be the most profitable hybrid on your farm,” says Max Dietrich, production coordinator for the National Sunflower Association. There are many factors that contribute to high yields, he points out, and all sunflower hybrids have different characteristics that will produce or hinder top yields.
Jerry Miller, research geneticist at the USDA Northern Crop Science Lab, Fargo, N.D., says that some commercial seed companies are now marketing hybrids with better tolerance to sclerotinia, as well as resistance to the new strain of downy mildew that is tolerant to Apron. He says growers should ask seed companies about these products, or other hybrids particular to their needs.
Here are some tips in evaluating hybrid performance data, and in selecting hybrids for next year.
Yield—Performance averaged over many tests is called “yield stability.” Good yield stability means that a hybrid may or may not be the best yielder at all locations, but that it does rank high in yielding potential at many locations. A hybrid that ranks in the upper 20% at all locations exhibits better yield stability than one that is the top yielder at two locations, but ranks in the lower 40% at two other locations.
Oil content/composition— Select a high-oil hybrid over a low -oil hybrid with the same yield potential, but don't sacrifice yield in favor of oil content. The oilseed sunflower market pays a premium based on market price for over 40% oil (at 10% moisture) and discounts for oil less than 40%. Use the oleic percent to make sure a hybrid has a good possibility to make NuSun quality. A number of seed companies offer guarantees for mid-oleic (NuSun) levels, between 55-75%. As NuSun hybrid performance data builds each year, be sure to evaluate dependability or consistency of oleic levels for different NuSun hybrids.
Maturity— When comparing hybrids, use the maturity rating to make sure you are comparing apples to apples. Be realistic of your expected planting date, and mindful of the average killing frost in your area. Later-maturing hybrids generally yield higher than early hybrids. Maturity is especially important if planting is delayed. Often, with delayed planting, only an early hybrid will mature and exhibit its full yield potential. Yield, oil content, and test weight often are reduced when a hybrid is damaged by frost before it is fully mature. An earlier hybrid will likely be drier at harvest than a later hybrid, thus reducing drying costs. Consider planting hybrids with different maturity dates as a production hedge to spread risk, drydown and workload.
Moisture content—Harvesting sunflower at higher moisture contents may reduce bird damage and seed shattering loss during harvest. Seed must then be dried to 10% or less for storage.
Disease tolerance—The most economical and effective means of sunflower disease control is the planting of resistant or tolerant hybrids, and a minimum of three to four years rotation between successive sunflower crops. Most sunflower hybrids have resistance to Verticillium wilt, races 1 and 2 of downy mildew, and to two or more races of rust. Consult the seed company for information on the reaction of a particular hybrid to these and other diseases that may pose a risk in your growing area.
Self-pollination (or self-compatibility), recommended to be at least 90%, is another trait to keep in mind. It refers to the ability of the plant to pollinate itself despite unfavorable conditions for pollination.
Marketability— Multi-purpose hybrids that have flexibility in several markets have become popular with producers. Assess what market or combination of markets may give you the best price for your ‘flowers.
Serviceability—Companies and seed dealers provide different services, policies, and purchase incentives. Determine what services you need, such as credit, delivery, and return policy.
Sunflower hybrid selection information online
Following are sources of public sunflower hybrid performance information available online the Internet. Some sites have not yet posted online performance trial information data from the 2002 growing season, but will soon.
North Dakota State University Research and Research Extension Centers http://www.ag.ndsu.nodak.edu/recenthp.htm
South Dakota State University Crop Variety Trial Information http://plantsci.sdstate.edu/varietytrials/vartrial.html
Colorado State University Sunflower Page http://www.colostate.edu/Depts/SoilCrop/extension/CropVar/sunflower/sunflower.html
Kansas State University Research & Extension Crops and Soils Library http://www.oznet.ksu.edu/library/crpsl2/
University of Nebraska sunflower testing results http://varietytest.unl.edu/sunftst/2002/index.htm
Yield trial information can also be found on the National Sunflower Association website, www.sunflowernsa.com. Click on the link, “Especially for Producers,” then “Yield Trials.” There, you can also find a list of seed suppliers by clicking on the “Seed Suppliers/Buyers” link. – Tracy Sayler
Clearfield Varieties to be Released in ‘03
Mycogen and Seeds 2000 will have Clearfield seed available for planting in 2003, pending regulatory approval of herbicide for the crop.
Clearfield sunflower is conventionally bred sunflower resistant to imazamox herbicide for control of a wide array of grassy and broadleaf weeds. The Clearfield technology was developed by BASF.
Beyond is the product that will be labeled for Clearfield sunflower. A Section 18 label is being requested from the Environmental Protection Agency for the emergency use of Beyond on a limited amount of sunflower acreage in 2003. Regulatory issues with Canada that prevented the rollout of Clearfield sunflower last year are also expected to be resolved, says Mark Dahmer, who manages commercial development of Clearfield for BASF. “Pending approval, we anticipate a good introduction of Clearfield sunflower in 2003, with more seed companies involved and more seed and hybrids available in 2004,” he says.
Making Sense of Hybrid Statistics
Expected mean in plot trial information refers to the average performance number for a particular trait of all hybrids evaluated in the trial.
The coefficient of variability (C.V. %) often listed at the bottom of a table is a relative measure of the amount of variation or consistency recorded for a particular trait, expressed as a percentage of the mean. Generally, trials with low C.V. rates are more reliable for making hybrid choices than trials with higher C.V. rates. Trials with C.V. rates below 15-20% are generally considered to be reliable for comparing yield.
To accurately determine if one hybrid is better than another for a given trait, use the least significant difference value (LSD 5%) at the bottom of the table. This is a statistical way to indicate if a trait such as yield differs when comparing two hybrids. If two hybrids differ by more than the indicated LSD 5% value for a given trait, they would most likely differ again when grown under similar conditions. If two hybrids differ by less than the LSD for a particular trait, than there’s no statistical difference.
For example, if a performance trial table indicates one hybrid yielded 2,600 lbs/acre, compared to another hybrid in the same plot that yielded 2,310 lbs/acre, and the LSD for this particular plot trial data is 407 lbs/acre, there is no statistical difference in yield between the two varieties.
In another example, if the oil content percentage for one hybrid is 44 compared to 41 for another, and the LSD is 2.3, the first hybrid can be expected to have a higher oil content than the second hybrid, under similar growing conditions.
Give more weight to information from trials or fields close to your particular growing area. It’s best to compare relative performance over many years and locations. Consult with an agronomist or your local seed dealer for more specific hybrid information.
Chance of Buying Downy Mildew-Infected Seed is Slim
Some sunflower growers have raised concerns about buying seed that may be infected with strains of the downy mildew pathogen that are resistant to Apron seed treatment. However, Carl Bradley, North Dakota State University extension plant pathologist, says that although the pathogen which causes downy mildew in sunflower has been documented to be seed transmitted, the likelihood of this happening is highly unlikely, for the following reasons:
1) Most sunflower seed is produced in areas where Apron-resistant strains of the pathogen do not exist. Because most seed is treated with Apron, any Apron sensitive strains would be killed.
2) Downy mildew-infected sunflower plants often die before seed is produced.
3) Plants expressing downy mildew symptoms in a seed production field would be eradicated.
4) Downy mildew-infected plants are usually stunted in height; therefore, the combine header would most likely skip over any infected plants.
5) Downy mildew-infected plants that do happen to produce seed often produce blanks or very light seed that would be blown out the back of the combine during harvest, or would be eliminated during processing by cleaning equipment.
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