2013 Soybean Variety Trial Disease Ratings: Maturity Group V Frogeye Leaf Spot and Cercospora Blight

Tom Allen, Extension Plant Pathologist
By Tom Allen, Extension Plant Pathologist January 26, 2014 23:02
Severe frogeye leaf spot that has reached the leaf blighting phase (Photo courtesy of M. Newman - UT).

Severe frogeye leaf spot that has reached the leaf blighting phase (Photo courtesy of M. Newman – UT).

During the 2013 season I had the opportunity to rate the soybean variety trial plots for the presence of frogeye leaf spot as well as Cercospora blight (late-season Cercospora).  Contained within this post are links to the rating data for the Maturity Group V variety trial entries (MG V early, MG V late, and MG V Conventional/Liberty Link varieties).  Locations were rated based on a scale of 0 to 9 where 0=no disease present and 9=extreme disease characterized by leaves covered with frogeye leaf spot or, in the case of Cercospora blight, where leaves as well as pods and petioles were covered with purple/black discoloration associated with Cercospora blight.

Please note that tables include ratings from all of the locations and ratings may differ by location for each variety based on the environment encountered at that particular location during the season (e.g., compare Raymond to Falkner – Raymond was extremely dry throughout the 2013 season).  In addition, some subtle differences may have occurred at some locations with regards to the particular strain of the fungus, especially in the case of frogeye leaf spot.  The variability within the fungal population for this particular fungus can be extremely variable between two locations.  When choosing a variety, consider the reaction of that particular variety across several environments.  For the most part, varieties considered to be susceptible to frogeye leaf spot were susceptible at all locations rated.

Dots indicate missing values due to in most cases to complete leaf shed due to a late rating date.

Frogeye leaf spot and Cercospora blight ratings are contained in a separate file for each Maturity Group (either early, late, or conventional/liberty link).  Each page is marked with the particular disease in the header so there is no confusion regarding specific disease ratings.

Maturity Group V early – frogeye leaf spot ratings (Maturity Group V early frogeye leaf spot ratings)

Maturity Group V early – Cercospora blight ratings (Maturity Group V early Cercospora blight ratings)

Maturity Group V late – frogeye leaf spot ratings (Maturity Group V late frogeye leaf spot ratings)

Maturity Group V late – Cercospora blight ratings (Maturity Group V late Cercospora blight ratings)

Maturity Group V conventional/LibertyLink – frogeye leaf spot ratings (Maturity Group V conventional-LibertyLink frogeye leaf spot ratings)

Maturity Group V conventional/LibertyLink – Cercospora blight ratings (Maturity Group V conventional-LibertyLink Cercospora leaf blight ratings)

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Tom Allen, Extension Plant Pathologist
By Tom Allen, Extension Plant Pathologist January 26, 2014 23:02
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