2018 Soybean OVT Foliar Disease Evaluations: Maturity Group V

Field evaluations of the Maturity Group V 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, southern blight, 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 were only included in situations where the disease was observed with any frequency.  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.  Southern blight was based on the presence of the disease within the entire plot based on a 0 to 9 scale where 0=no disease, 5=approximately half of the plot exhibiting symptoms and 9=severe southern blight characterized by dead plants.  In a lot of cases, signs associated with southern blight (either white fungal growth or sclerotia) were observed at the base of infected plants.

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

Maturity Group V Early (n=11 locations):

Cercospora blight MG V early Cercospora leaf blight

Septoria brown spot MG V early Septoria brown spot

Southern blight MG V early Southern blight

Target spot MG V early Target spot

Maturity Group V Late (n=11 locations):

Cercospora blight MG V late Cercospora leaf blight

Septoria brown spot MG V late Septoria brown spot

Southern blight MG V late Southern blight

Target spot MG V late Target spot

Maturity Group V Conventional (n=2 locations):

Cercospora blight MG V Conventional Cercospora leaf blight

Septoria brown spot MG V Conventional Septoria brown spot

Southern blight MG V Conventional Southern blight

Target spot MG V Conventional Target spot

Maturity Group V LibertyLink (n=5 locations):

Cercospora blight MG V LL Cercospora leaf blight

Septoria brown spot MG V LL Septoria brown spot

Southern blight MG V LL Southern blight

Target spot MG V LL Target spot