Septoria Leaf Blotch on Wheat

May 21, 1999
Marion Shier, Crop Systems Educator in Livingston County, reports Septoria leaf blotch on wheat in the area. Shier indicated that the wheat was already headed and the leaf blotch was infecting the flag and flag-1 leaves. See issue no. 6 of the Bulletin to estimate probable yield loss from fungal leaf diseases.

Septoria leaf blotch is caused by the fungus Septoria tritici. The fungus produces tan-colored, oval-shaped lesions on the leaves. As the lesions mature, small, black specks can be seen in the lesion. The specks are the fruiting structures of the fungus called pycnidia. During periods of high moisture, the pycnidia will produce spores and the spores are splashed up to successive leaves on the plant, usually by rain. Effective fungicide controls for leaf blotch are not labeled for use after Feeke's growth stage 10.5. The only thing that will keep disease levels from leaf blotch down beyond growth stage 10.5 is dry weather.--Suzanne Bissonnette

Author: Suzanne Bissonnette