UTIA-3stacked

Information about database

Each year commercial seed companies enter cultivars in the UT county standardized tests (CSTs), which are conducted in 18 or more counties in Tennessee and 3 to 4 counties in Western Kentucky. Each cultivar is evaluated in a large strip-plot at each location, thus each county test is considered as one replication of the test in calculating overall average yield (‘County Tests Avg Yield’ in database) and performing statistical analysis to identify top yielding cultivars (in database includes ‘Yield Performance in County Tests’ and ‘Top yielding cultivars in consecutive years’). The determination of ‘Top Yielding Cultivars In County Tests and Consecutive years’ are based on comparisons and statistics within herbicide traits and with specific maturity group (i.e. III, early IV, late IV, or V) trials not across all search parameters. More detailed information about the CSTs can be found at utcrops.com/soybean/varieties_soy under year PDFs of Experiment Station and County Variety Data.

The same cultivars in the CSTs are evaluated for disease susceptibility and response to fungicide at 2 to 3 different locations in West Tennessee in replicated and randomized small plots. The locations vary by disease pressure defined by cropping history, irrigation, and previous level of disease. All locations are no-till production. In the database:

  • High Disease Pressure Locations’ Yields include those from a continuous soybean location under irrigation with a history of high levels of disease (specifically frogeye leaf spot)
  • Low-Moderate Disease Pressure Locations’ Yields include those from a dryland, on-farm location, with a history of low to moderate levels of disease
  • Behind Wheat Locations (Low-Moderate)’ Yields include those from a double crop (soybeans planted after wheat harvest), dryland location that has been regularly rotated (corn-wheat-soybean) with a history of low to moderate levels of disease.

 

Each cultivar is planted in 4-row plots where 2 of the 4 rows are treated around growth stage R3 (beginning pod) with 8 fl oz/a of Quadris Top® (Syngenta Crop Protection). Hence, under each location in the database there is a ‘Treated Yield’ and ‘Nontreated Yield’ column. The main disease rated is frogeye leaf spot (FLS), using 0-100% scale based on leaf area affected and has been converted to LOW (little to no FLS developed/Good resistance to FLS), MOD (moderate levels of FLS developed/Moderate resistance to FLS), and HIGH (high levels of FLS developed/Poor resistance to FLS) in the database. Other diseases observed or rated are also listed in the database under ‘Other Diseases’, which include sudden death syndrome (SDS), stem canker (SC), target spot (TS), Cercospora leaf blight (CLB), and brown spot (BS). Lastly each cultivar is evaluated by USDA for soybean cyst nematode resistance. Each year 3 different races or HG types were used to rate resistance in greenhouse trials and based on the reproduction ability, in reference to a susceptible check, cultivars were rated: Highly Susceptible (HS), Susceptible (S), Moderately Susceptible (MS), Moderately Resistant (MR), or Resistant (R).

More information about soybean diseases can be found at UTcrops.com/soybean/diseases as well as PDF files containing the information in the database (the yearly ‘Soybean Disease Ratings and Yields – UT Summaries’) including specific planting, application, and harvest information. Additional information about soybean cultivars can be found at UTcrops.com/soybean/varieties_soy.

 

Database
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