Take-all in low N and adequate N environment. The disease also prefers compacted poorly drained fields where moisture is not in short supply. Yield losses will depend on how severely the roots and culms are infected and how early the disease showed up. Symptoms are quite recognizable at heading. Infected plants usually show up in localized patches in a field, and heavily infected plants appear light green and somewhat stunted, and will ripen and die prematurely.
Infected plants develop sterile or nearly sterile white heads with a few or no shriveled kernels.
The field diagnostic symptom, though, is present on the base of the stem. Peel back the leaf sheath of the lowest leaf and you will see a superficial covering of shiny black fungus. Black mycelial mat of takeall. Don't get too carried away with field pattern for this disease. It can show up in the more typical patches, or an entire field can be affected, or, as a few people know I have been stymied by, it can follow very subtle pH changes in a field and mimic spray damage.