2009 MISSOURI WINTER WHEAT PERFORMANCE TESTS
A. L. McKendry, D. N. Tague, J. K. Solomon, B. J. Craughwell

Description of Data Collected

Yield

All rows of each test plot were measured for length and harvested using a Kincaid™ experimental plot combine. Recorded grain yields were adjusted to 13% grain moisture and reported in bushels per acre based on a 60 pound standard bushel weight. In addition to yields obtained in 2009, two-year averages (2008-09), and three-year averages (2007-09) are provided for those entries tested in the Missouri tests for two or three consecutive years, respectively.

Test Weight and Grain Moisture Content

Test weight (pounds per bushel) and percentage grain moisture were determined for grain from each plot using a Dickey-john GAC 2100b™ grain analyzer.

Plant Height

Plant height was measured in inches from the soil surface to the top of the head, excluding awns if present. Reported values have been rounded to the nearest inch.

Lodging

Lodging severity at crop maturity was rated at all test locations. Plots were rated on a severity scale of 0 to 9 where 0=no lodging and 9=plants in the plot were completely flat.

Winter Survival

Percent winter survival was estimated for each plot after initial spring green-up (approximately Feeke’s GS 6) at all locations. Reported values have been rounded to the nearest percent.

Heading Date

Heading dates were recorded when 50% of the heads in a plot had extended above the flag leaf collar. Heading dates were recorded in Julian days (number of days after January 1) for statistical purposes. The corresponding calendar dates are also presented.

Disease Ratings

Due to persistent rainfall at heading, significant levels of Fusarium head blight, (FHB, or scab), were present throughout the state and were rated at 5 of the 7 locations as the percentage of florets in the canopy expressing symptoms. Ratings were taken approximately 21 days after the mean flowering date for the location, however, at most locations, symptoms progressed for at least another week, thus losses due to scab in susceptible varieties are probably underestimated based on this single score. At the Lamar location (Table 11) ratings were taken at 21 days and again at 28 days post flowering and indicated that disease had progressed by as much as 56% in the most susceptible variety. For the more resistant varieties, disease progression between 21 and 28 days was minimal. Over all varieties at the Lamar location, the mean level of disease increased during this week interval from 2.3% infected florets to 17.5% infected florets. In an effort to provide information on the FHB resistance level of varieties tested, each variety was entered into a separate FHB nursery at Columbia where it was rated for FHB in the greenhouse, and field under conditions of artificial inoculation and over-head misting. In the field FHB nursery, entries were sprayed with a macroconidial suspension of Fusarium graminearum and rated for disease incidence (percentage of heads in the plot showing symptoms of FHB), severity (the percentage of spikelets on the inoculated heads showing symptoms) and the Field Scab Index (Index = incidence x severity). Resistance was also rated in the greenhouse under point inoculation to evaluate disease spread within the head. Reported data for severity were determined as the ratio of diseased spikelets on the inoculated head to the total number of spikelets on the inoculated head expressed as a percentage. These data from our inoculated nurseries indicate the potential for loss in a variety under heavy disease pressure in the field environment. Although it is difficult to predict when FHB will impact the crop, selection of a variety that is more resistant rather than highly susceptible can lessen losses in epidemic years.

Low levels of other foliar diseases were present at many locations, but levels were not considered significant enough to reduce yields, except at the Mt. Vernon location where foliar diseases, predominantly Septoria tritici blotch, was rated as percentage of the canopy showing disease symptoms.

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