2018 Soybean OVT Foliar Disease Evaluations: 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 (n=2), Clarksdale, Longwood, Olive Branch, Raymond, Stoneville (n=3), Tippo, and Verona).  Entries were observed for their reaction to the diseases that occurred at each location. Cercospora blight, Septoria brown spot and Target spot were the three most common diseases encountered at each location.  However, 2018 was not a good year for frogeye evaluations therefore frogeye leaf spot evaluations are not included.  Plots were observed between R6 and R6.5.  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.  Cercospora leaf blight was evaluated 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 evaluated 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.

Note that locations with a non-irrigated trial are marked as location (N) with an “N” in parentheses to indicate non-irrigated.

Maturity Group IV Early (n=11 locations):

Cercospora blight MG IV early Cercospora blight

Septoria brown spot MG IV early Septoria brown spot

Target spot MG IV early target spot

Maturity Group IV Late (n=11 locations):

Cercospora blight MG IV late Cercospora blight

Septoria brown spot MG IV late Septoria brown spot

Target spot MG IV late target spot

Maturity Group IV Conventional (n=2 locations):

Cercospora blight MG IV Conventional Cercospora blight

Septoria brown spot MG IV Conventional Septoria brown spot

Target spot MG IV Conventional target spot

Maturity Group IV LibertyLink (n=5 locations):

Cercospora blight MG IV LibertyLink Cercospora blight

Septoria brown spot MG IV LibertyLink Septoria brown spot

Target spot MG IV LibertyLink target spot