December 2008


Joe Lauer, Kent Kohn, and Thierno Diallo

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The University of Wisconsin Extension-Madison and College of Agricultural and Life Sciences conduct a corn evaluation program, in cooperation with the Wisconsin Crop Improvement Association. The purpose of this program is to provide unbiased performance comparisons of hybrid seed corn available in Wisconsin . These trials evaluate corn hybrids for both grain and silage production performance.

In 2008, grain and silage performance trials were planted at fourteen locations in four production zones. Both seed companies and university researchers submitted hybrids. Companies with hybrids included in the 2008 trials are listed in Table 1. Specific hybrids and where they were tested are shown in Table 2. In the back of the report, hybrids previously tested over the past three years are listed (Table 27). At most locations trials were divided into early and late maturity trials, based on the hybrid Relative Maturities provided by the companies. The specific Relative Maturities separating early and late trials are listed below.


Seasonal precipitation and temperature at the trial sites are shown in Table 4. Spring planting was delayed due to cool and wet planting conditions. Plant stands in the trials were excellent. Above normal precipitation occurred during June leading to some flood damage in southern Wisconsin. During August and September, drought stress was evident on corn plants in northwestern Wisconsin affecting hybrid performance at Chippewa Falls and Spooner. For southern Wisconsin, accumulation of growing degree units for the entire season was below average. Plant development variability within a field was often high. Little insect or disease pressure was observed in most trials. Standability was excellent, except after a wide-spread storm with rain and high winds that occurred in late October affecting some trials that hadn’t been harvested yet. A killing frost occurred in late-October. Harvest grain moisture was higher than normal in southern late maturity trials. Yields in the UW hybrid trials were average to above average at most sites. Plots at the Rhinelander location were not harvested due to poor emergence.


The seedbed at each location was prepared by either conventional or conservation tillage methods. Seed treatments of hybrids entered into the trials are described in Table 3. Fertilizer was applied as recommended by soil tests. Herbicides were applied for weed control and supplemented with cultivation when necessary. Corn rootworm insecticide was applied when the previous crop was corn. Information for each location is summarized in Table 5.


A precision vacuum corn planter was used at all locations, except Spooner. Two-row plots, twenty-five foot long, were planted at all locations. Plot were not hand-thinned. Each hybrid was grown in at least three separate plots (replicates) at each location to account for field variability.


Grain: Two-row plots were harvested with a self‑propelled corn combine. Lodged plants and/or broken stalks were counted, plot grain weights and moisture contents were measured and yields were calculated and adjusted to 15.5% moisture. Test weight was measured on each plot.

Silage: Whole‑plant (silage) plots were harvested using a tractor driven, three-point mounted one-row chopper. One row was analyzed for whole plant yield and quality. Plot weight and moisture content were measured, and yields were adjusted to tons dry matter / acre. A sub-sample was collected and analyzed using near infra-red spectroscopy.

Wisconsin Relative Maturity Belts and test sites.


Southern Zone
Arlington, East Troy, Janesville, Lancaster

Early Maturity Trial: 105‑day or earlier
Late Maturity Trial: later than 105‑day

Table 6
Table 7

South Central Zone
  Fond du Lac , Galesville, Hancock (irrigated)

Early Maturity Trial: 100‑day or earlier
Late Maturity Trial: later than 100‑day

Table 8
Table 9

North Central Zone
Chippewa Falls , Marshfield , Seymour , Valders

Early Maturity Trial: 90‑day or earlier
Late Maturity Trial: later than 90‑day

Table 10
Table 11

Northern Zone
   Spooner (three sites), Marshfield


Table 12


Southern Zone
  Arlington and Lancaster

Early Maturity Trial: 109‑day or earlier
Late Maturity Trial: later than 110‑day

Table 13
Table 14

South Central Zone
  Fond du Lac and Galesville

Early Maturity Trial: 104-day or earlier
Late Maturity Trial: later than 104-day

Table 15
Table 16

North Central Zone
  Chippewa Falls, Marshfield, Valders

Early Maturity Trial: 99‑day or earlier
Late Maturity Trial: later than 99‑day

Table 17
Table 18

Northern Zone
  Spooner (two sites), Marshfield


Table 19

Specialty Trials

Southern Zone
Arlington, East Troy, Janesville, Lancaster

Corn Rootworm Trial
Organic Trial
Refuge Trial
Roundup Ready Trial

Table 20
Table 21
Table 22
Table 23

South Central Zone
Fond du Lac, Galesville, Hancock (dryland)

Corn Rootworm Trial
Dryland Trial
Roundup Ready Trial

Table 24
Table 25
Table 26



Yield results for individual location trials and for multi‑location averages are listed in Tables 6 through 26. Within each trial, hybrids are ranked by moisture, averaged over all trials conducted in that zone during 2008. Yield data for both 2007 and 2008 are provided if the hybrid was entered previously in the 2007 trials. A two-year average for yield is calculated using location means as replications. In the Corn Rootworm and Roundup Ready specialty trials, a multi-location average is calculated using trial means within a production zone as replications. In the specialty Dryland trial at Hancock, an average was calculated using data from both the dryland and irrigated trials using trial as replications. A hybrid index (Table 2) lists relative maturity ratings, specialty traits, seed treatments and production zones tested for each hybrid. 


Seed companies use different methods and standards to classify or rate the maturity of corn hybrids. To provide corn producers a “standard” maturity comparison for the hybrids evaluated, the average grain or silage moisture of all hybrids rated by the company relative maturity rating system are shown in each table as shaded rows. In these Wisconsin results tables, hybrids with lower moisture than a particular relative maturity average are likely to be earlier than that relative maturity, while those with higher grain moisture are most likely later in relative maturity. Company relative maturity ratings are rounded to 5-day increments.

The Wisconsin Relative Maturity rating system for grain and silage (GRM and SRM) compares harvest moisture of a grain or silage hybrid to the average moisture of company ratings using linear regression. Each hybrid is rated within the trial and averaged over all trials in a zone. Maturity ratings (Company, GRM and SRM) can be found in Table 2.


Three factors—yield, moisture, and standability—are of primary importance in evaluating and selecting corn hybrids. A performance index (P.I.), which combines these factors in one number, was calculated for multi‑location averages for grain trials. This performance index evaluates yield, moisture, and lodged stalks at a 50 (yield): 35 (moisture): 15 (lodged stalks) ratio.

The performance index was computed by converting the yield, dry matter, and upright stalk values of each hybrid to a percentage of the test average. Then the performance index for each hybrid that appears in the tables was calculated as follows:

Performance Index (P.I.) = [(Yield x 0.50) + (Dry matter x 0.35) + (Upright stalks x 0.15)] / 100


Corn silage quality was analyzed using near infra-red spectroscopy equations derived from previous work. Plot samples were dried, ground, and analyzed for crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro cell wall digestibility (NDFD), in vitro digestibility (IVD), and starch. Spectral groups and outliers were checked using wet chemistry analysis.

The MILK2006 silage performance indices, milk per ton and milk per acre, were calculated using an adaptation by Randy Shaver (UW-Madison Dairy Science Department) of the MILK91 model (Undersander, Howard and Shaver; Journal Production Agriculture 6:231-235). In MILK2006, the energy content of corn silage was estimated using a modification of a published summative energy equation (Weiss and co-workers, 1992; Animal Feed Science Technology 39:95-110). In the modified summative equation, CP, fat, NDF, starch, and sugar plus organic acid fractions were included along with their corresponding total-tract digestibility coefficients for estimating the energy content of corn silage. Whole-plant dry matter content was normalized to 35% for all hybrids. The sample lab measure of NDFD was used for the NDF digestibility coefficient. Digestibility coefficients used for the CP, fat, and sugar plus organic acid fractions were constants. Dry matter intake was estimated using NDF and NDFD content assuming a 1350 lb. cow consuming a 30% NDF diet. Using National Research Council (NRC, 2001) energy requirements, the intake of energy from corn silage was converted to expected milk per ton. Milk per acre was calculated using milk per ton and dry matter yield per acre estimates.


Variations in yield and other characteristics occur because of variations in soil and growing conditions that lower the precision of the results. Statistical analysis makes it possible to determine, with known probabilities of error, whether a difference is real or whether it might have occurred by chance. Use the appropriate LSD (least significant difference) value at the bottom of the tables to determine true differences.

Least significant differences (LSD’s) at the 10% level of probability are shown. Where the difference between two selected hybrids within a column is equal to or greater than the LSD value at the bottom of the column, you can be sure in nine out of ten chances that there is a real difference between the two hybrid averages. If the difference is less than the LSD value, the difference may still be real, but the experiment has produced no evidence of real differences. Hybrids that were not significantly lower in performance than the highest hybrid in a particular test are indicated with an asterisk (*).


The results can be used to provide producers with an independent, objective evaluation of performance of unfamiliar hybrids, promoted by seed company sales representatives, compared to competitive hybrids.

Below are suggested steps to follow for selecting top‑performing hybrids for next year using these trial results:

  Use multi-location average data in shaded areas. Consider single location results with extreme caution.

2.  Begin with trials in the zone(s) nearest you.

3.  Compare hybrids with similar maturities within a trial. You will need to divide most trials into at least two and sometimes three groups with similar average harvest moisture—within about 2% range in moisture.

4.  Make a list of 5 to 10 hybrids with highest 2008 Performance Index within each maturity group within a trial.

5.  Evaluate consistency of performance of the hybrids on your list over years and other zones.

a.  Scan 2007 results. Be wary of any hybrids on your list that had a 2007 Performance Index of 100 or lower. Choose two or three of the remaining hybrids that have relatively high Performance Indexes for both 2007 and 2008.

b.  Check to see if the hybrids you have chosen were entered in other zones. (For example, some hybrids entered in the Southern Zone Trials, Tables 6 and 7, are also entered in the South Central Zone Trials, Tables 8 and 9).

c.  Be wary of any hybrids with a Performance Index of 100 or lower for 2007 or 2008 in any other zones.

6.  Repeat this procedure with about three maturity groups to select top‑performing hybrids with a range in maturity, to spread weather risks and harvest time.

7.  Observe relative performance of the hybrids you have chosen based on these trial results in several other reliable, unbiased trials and be wary of any with inconsistent performance.

8.  You might consider including the hybrids you have chosen in your own test plot, primarily to evaluate the way hybrids stand after maturity, dry‑down rate, grain quality, or ease of combine‑shelling or picking.

9.  Remember that you don’t know what weather conditions (rainfall, temperature) will be like next year. Therefore, the most reliable way to choose hybrids with greatest chance to perform best next year on your farm is to consider performance in 2007 and 2008 over a wide range of locations and climatic conditions.

You are taking a tremendous gamble if you make hybrid selection decisions based on 2008 yield comparisons in only one or two local test plots.


This report is available on the internet at Hybrid performance for the last 10 years can be summarized using SELECT at the above internet address. This book can be downloaded over the internet in Microsoft Excel and Acrobat PDF formats.

About the authors: Joe Lauer is a professor of agronomy and also holds an appointment with University of Wisconsin-Extension. Kent Kohn is the corn program manager in agronomy and Thierno Diallo is an assistant research specialist in agronomy.

This publication is available from your Wisconsin County Extension office or from the Department of Agronomy, 1575 Linden Drive, Madison, WI 53706 . Phone (608) 262-1390.

University of Wisconsin-Extension, Cooperative Extension, in cooperation with the U.S. Department of Agriculture and Wisconsin counties, publishes this information to further the purpose of the May 8 and June 30, 1914 Acts of Congress; and provides equal opportunities and affirmative action in employment and programming.

References to transgenic traits in this publication are for your convenience and are not an endorsement or criticism of one trait over other similar traits. Every attempt was made to ensure accuracy of traits in the hybrids tested. You are responsible for using traits according to the current label directions of seed companies. Follow directions exactly to protect the environment and people from misuse. Failure to do so violates the law. 

If you need this material in an alternative format, contact Cooperative Extension Publications at (608) 262-2655 or the UWEX Affirmative Action office. This publication is available free from your Wisconsin county Extension office or from the Department of Agronomy, 1575 Linden Dr., Madison, Wisconsin 53706. Phone (608) 262-1390 

A3653 2008 Wisconsin Hybrid Corn Performance Trials - Grain and Silage.

University of Wisconsin, 1575 Linden Drive - Agronomy, Madison WI  53706    (608) 262-1390
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