2015 Soybean OVT Foliar Disease Ratings: Maturity Group IV

Field evaluations of the Maturity Group IV entries in the MSU OVT were conducted at each of the locations where trials were planted (Brooksville, Clarksdale (n=2), Falkner, Longwood, Raymond, and Stoneville (n=3)).  Entries were observed for their reaction to the diseases that occurred at each location.  Cercospora blight and frogeye leaf spot were the two most commonly observed diseases; however, Septoria brown spot and Target spot were also observed at some locations.  Plots were observed between R6 and R6.5 and a second observation was made immediately prior to harvest to assess green stem severity (at all locations except Longwood).   Field evaluations for the presence of foliar disease were conducted using a 0 to 9 scale whereby 0=no disease and 9=excessive disease symptoms.  Leaf surface area affected was evaluated for FLS while CLB was rated based on the presence of disease on leaves (0 to 5), petioles (6), and on pods and stems (7 to 9) based on disease intensity as assessed by coloration of plant material (leaves with distinct purple coloration and petioles, pods and main stems with purple to near black coloration).  Septoria brown spot and target spot were rated in a similar fashion based on the presence of the disease within the plant canopy so that 0 to 3 indicated the presence in the lower canopy, 4 to 5 in the middle canopy, 6 to 8 in the upper canopy, and 9 indicative of extensive defoliation throughout the entire plant canopy and the disease in the upper most canopy.  One location, Longwood (near Leland, MS) was rated for the presence of phytotoxicity that followed an accident application of Quadris Top (8 fl oz).  However, observations were only made in the Maturity Group IV early and late entries.  Observations of phytotoxicity were made using a 0-9 scale and based on the severity of the phytotoxicity present post-application whereby 0=no observable symptoms of injury, 1=mild symptoms, 5=moderate symptoms, and 9=severe symptoms.

Yield information, in Excel or pdf files, are available in a preliminary form on the MSU Variety testing website that can be accessed by following this link:

http://www.mafes.msstate.edu/variety-trials/includes/crops/soybeans.asp

Maturity Group IV Early:

Cercospora blight (n=9 locations) (2015 MG IV early Cercospora)

Frogeye leaf spot (n=9 locations) (2015 MG IV early Frogeye)

Septoria brown spot (n=8 locations) (2015 MG IV early Septoria)

Target spot (n=5 locations) (2015 MG IV early Target)

Green stem (n=8 locations) (2015 MG IV early Green stem)

Phytotoxicity (n=1 location) (2015 MG IV early Phytotoxicity)

Maturity Group IV Late:

Cercospora blight (n=9 locations) (2015 MG IV late Cercospora)

Frogeye leaf spot (n=9 locations) (2015 MG IV late Frogeye)

Septoria brown spot (n=7 locations) (2015 MG IV late Septoria)

Target spot (n=6 locations) (2015 MG IV late Target)

Green stem (n=8 locations) (2015 MG IV late Green stem)

Phytotoxicity (n=1 location) (2015 MG IV late Phytotoxicity)

Maturity Group IV Conventional:

Cercospora blight (n=1 location) (2015 MG IV conventional Cercospora)

Frogeye leaf spot (n=1 location) (2015 MG IV conventional Frogeye)

Septoria brown spot (n=1 location) (2015 MG IV conventional Septoria)

Green stem (n=1 location) (2015 MG IV conventional Green stem)

Maturity Group IV LibertyLink:

Cercospora blight (n=3 locations) (2015 MG IV LibertyLink Cercospora)

Frogeye leaf spot (n=3 locations) (2015 MG IV LibertyLink Frogeye)

Septoria brown spot (n=3 locations) (2015 MG IV LibertyLink Septoria)

Target spot (n=2 locations) (2015 MG IV LibertyLink Target)

Green stem (n=3 locations) (2015 MG IV LibertyLink Green stem)