2007 Wheat Crop Review

Crop Development

Progress of the 2007 wheat crop followed uneven patterns across the state. Planting and emergence followed close to the pace of recent years, except for southeastern areas that were delayed by rains and western parts of the state that were delayed by lack of moisture. Jointing began significantly earlier than the 5-year average with 46% of the crop jointed by April 2. After record-low temperatures in early April, the progress of the wheat that was still alive slowed to the point that heading was significantly behind last year and the 5-year average. Warmer temperatures in May and June helped hasten growth, but frequent rains delayed harvest in many parts of the state. As of July 9 only 81% of the wheat crop had been harvested.

The condition of the 2007 wheat prior to the April freeze rated 77% of the crop as either good or excellent. The quality of the crop sharply declined in the next few months as the full extent of damage caused by the freezing temperatures was reported. The wheat rebounded somewhat in late May and June but remained stressed by foliar diseases and late-season rains. In late June, 32% of the wheat acres were rated as good or excellent, 40% were rated as poor to very poor, leaving 28% in the fair category.
(Crop-Weather reports, Kansas Ag. Statistics).

Weather

The 2007 wheat season was again characterized by uneven conditions, both in temperature and precipitation. The western parts of the state experienced mostly ideal wheat weather conditions, while the rest of the state faced various weather challenges.

The western third of the state was wetter than average in the fall, which allowed for good stand establishment. This was followed by the wettest winter conditions (Dec-Feb) on record. Much of this moisture came in the form of snow. Many locations saw continuous snow cover from mid-December through mid-March. The snow cover provided protection from temperature changes, and left much of the wheat in a less vulnerable state when the early April freeze hit. Drier, but still favorable, moisture conditions continued through the spring. A generally dry harvest period put the cap on a nearly ideal growing season. Some problems were seen in Northwest Kansas where cool, wet soils limited root development, which was then stressed by the drier spring conditions. Northwest Kansas did not escape hailstorms, but the most severe hail events were in north central Kansas.

For the rest of the state, generally favorable fall and winter growing conditions came to a screeching halt in April, when record cold temperatures- in the low teens- plunged into Oklahoma. Since March temperatures were warmer than normal, much of the wheat was actively growing and quite vulnerable to the extreme cold. This was followed by excessively wet and cool conditions in May and June. Flooding was a widespread problem in central and south central Kansas in May. This moved to east central and southeast parts in June. While flooding wasn’t as widespread in the north central and northeastern areas, continued wet weather contributed to harvest delays and aggravated disease and condition problems.
(Mary Knapp, K-State Weather Data Library).

Diseases

Frequent rainfall and extended periods of high relative humidity favored the development of fungal diseases. Leaf rust was severe in 2007 and was probably the most important disease in Kansas. Trace levels were reported as early as mid-March. In many locations, leaf rust had destroyed the leaves of susceptible varieties by the early stages of grain fill. Stripe rust was an important factor in western Kansas where the disease pressure was moderate to high on susceptible varieties. Stripe rust could be found at most locations in central Kansas, but the disease appeared to be held in check by the widespread use of resistant varieties.

Powdery mildew was severe in many fields in the eastern two-thirds of the state, and persisted well into the heading stages of growth. Speckled leaf blotch was also at elevated levels; it is spread by splashing rain and frequent showers. This year created an ideal environment for disease development. Tan spot was a problem during stem elongation in north central Kansas and was severe in continuous wheat fields. Low levels of head scab were reported in parts of eastern and central Kansas and likely played a role in the below average test weights experienced in many fields.

Barley yellow dwarf (BYD) was the most common viral disease in 2007 in central and eastern Kansas. Tillers damaged by freezing conditions in April appeared to provide an ideal environment for the aphid populations which spread BYD, possibly complicating the recovery from the freeze. Wheat streak mosaic was reported in some fields in western Kansas. Soilborne mosaic and spindle streak were also present, but it appears that the use of resistant varieties continues to provide good protection from the damaging effects of these diseases.
(K-State Extension Plant Pathologist, Erick DeWolf).

Insects

Winter grain mites generated considerable interest in the fall of 2006. These small pests became numerous and active from November until mid-January when cold temperatures stopped their activity. Winter grain mites annually cause grower concern but rarely cause economic losses.

Bird cherry oat aphids (BCOA) are efficient vectors of the virus that causes barley yellow dwarf, but are usually of little concern due to feeding damage only. However, BCOA populations exploded throughout the state after the unusually cold weather in April. This created considerable concern and resulted in many acres being treated. Insecticide treatment is seldom justified to control yield losses due to aphid feeding, but we had not previously experienced populations of this magnitude.

As BCOA populations declined, armyworm populations rapidly increased. Much like the BCOA situation, armyworms were more numerous and widely distributed than in previous years. Again, this resulted in many acres treated to prevent yield reductions.

Hessian fly adults were active through November in south central Kansas, according to pheromone trapping data. Hessian fly infestations were difficult to determine however, due to the freeze-affected and extremely wet weather experienced in the spring of 2007.
(K-State Extension Entomologist, Jeff Whitworth)..

Harvest Statistics

The Kansas Agricultural Statistics’ July 12 estimate of the 2007 crop was 300.8 million bushels from 9.4 million acres, with a 32 bushels/acre yield average, identical to last year’s yield.
(July 12, 2007, CROPS report, Kansas Ag. Statistics, Topeka).

Acreage Distribution

Overley replaced Jagalene by a very small margin as the variety planted on the most acres in Kansas in 2007. Jagger fell to the third spot, with 17.1 of the statewide acreage, and TAM 111 moved into fourth place. Hard white varieties occupied 0.1% of the 2007 wheat acreage, following a downward trend from last year. The acreage of blends did not change from 2006 and remained at 10%.
(February 5, 2007, Wheat Variety, Kansas Ag. Statistics, Topeka).

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2007 Performance Tests

The Kansas Agricultural Experiment Station annually compares both new and currently grown varieties in the state’s major crop-producing areas. These performance tests generate unbiased performance information designed to help Kansas growers select wheat varieties suited for their area and conditions.

Varieties Included

Public varieties are selected for inclusion in the tests on the basis of several criteria. Most represent new or established varieties with potential for successful use in Kansas. Some are included as long-term checks. Others are entered at the request of the originating institution.

Originators or marketers enter privately developed varieties on a voluntary basis. Entrants choose both the entries and test sites and pay a fee to help defray test expenses. The 2007 private entrants are listed in Table 1. Eleven entrants provided a total of 37 varieties for testing.

Table 13 describes the characteristics of seed submitted for testing. Seed quality- including such factors as size, purity, and germination- can be important in determining the performance of a variety. Wheat seed used for entries in the Kansas Crop Performance Tests is prepared professionally and usually meets or exceeds Kansas Crop Improvement Certification standards. Performance of a given variety comparable to that obtained in these tests is best assured under similar environmental and cultural conditions and with the use of certified or professionally prepared seed.

Environmental Factors

Many plants in these tests lost primary tillers during the freeze in April, stimulating late secondary and tertiary tillers that delayed harvest and introduced additional variability. All locations affected by the freeze had some degree of lodging. Many tests, especially those in SE Kansas, were completely lodged by harvest.

Leaf rust and stripe rusts were reported at all testing locations, however leaf rust developed later in the season in the southwest dryland, northwest dryland, and irrigated regions and had little effect on yields. Leaf rust caused near total defoliation in many varieties after heading at the Beloit test in the north central region. Tests in the southeast region were affected by powdery mildew, barley yellow dwarf virus, and head scab due to the frequent rains. The dryland test at Hesston in the South Central region reported incidence of soilborne mosaic virus and spindle streak mosaic virus.

Hessian flies caused some concern in the northwest dryland region. Wheat head army worms took most of the leaves after heading at the Southeast region tests.

Site descriptions and management practices for each site are summarized in Table 4. One-year or one-location results can be misleading because of the possibility of unusual weather or pest conditions. Be sure to keep extenuating environmental conditions in mind when examining test results.

Results and Variety Characterization

Results from Kansas tests are presented in Tables 4 through
11. Yields are reported as bushels per acre (60 pounds per bushel) adjusted to a moisture content of 13%, where moistures were reported at harvest. Yields also are converted to percentages of the test average to speed recognition of highest yielding entries. Multi-year averages are presented for those varieties entered more than one year.

Additional information, such as test weight, heading date, and plant height, is helpful for fine-tuning variety comparisons. For example, a relatively tall variety may yield well in the tests, but may not be appropriate for some situations. Conversely, some producers may want a tall variety for straw production. Planting varieties with a range of maturities helps minimize weather risks.

At the bottom of each table is the (0.05) LSD (least significant difference) for each column of replicated data. One can think of the LSD as a “margin of error” that shows how big the difference between two varieties must be for one to be 95% confident that the difference is real. The use of the LSD is intended to reduce the chance of overemphasizing small differences. Small variations in soil structure, fertility, water-holding characteristics, and other test-site characteristics can cause considerable yield variation among plots of one variety.

Performance Summaries

Figures 3 through 9 summarize the performance of each variety standardized to the average of two widely grown, check varieties: Jagger and 2137. The number at the base of each bar indicates the number of direct comparisons with the check varieties. Values that differ significantly from the average of the two check varieties are indicated by a + or – at the end of the bar.

Research and Duplication Policy

When companies submit entries, permission is given to Kansas State University to test varieties and/or hybrids designated on the entry forms in the manner indicated in the test announcements. Seed submitted for testing should be a true sample of the seed being offered for sale.

All results from Kansas Crop Performance Tests belong to the University and the public and shall be controlled by the University so as to produce the greatest benefit to the public. Performance data may be used in the following ways: 1) Tables may be reproduced in their entirety, provided the source is referenced and data are not manipulated or reinterpreted; 2) Advertising statements by an individual company about the performance of its entries may be made as long as they are accurate statements about the data as published, with no reference to other companies’ names or cultivars. In both cases, the following must be included with the reprint or ad citing the appropriate publication number and title: “See the official Kansas State University Agricultural Experiment Station and Cooperative Extension Service Report of Progress 982 ‘2007 Kansas Performance Tests with Winter Wheat Varieties,’ or the Kansas Crop Performance Test website, http://kscroptests.agron.ksu.edu, for details. Endorsement or recommendation by Kansas State University is not implied.”

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