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Wheat Take-all symptoms are most obvious at heading. Diseased plants occur in
patches within the field. They are shorter in height than surrounding healthy plants and
die prematurely at heading. Their heads are bleached (whiteheads) and may be sterile or
contain few, severely shriveled seeds. Typically, take-all infected plants pull out or
bread off easily at the soil line. The base and culms of infected plants have sparse root
development and characteristically a brown-black rot can be seen at the crown and
extending to the base of the stem of tiller under the leaf sheath that covers it. The
surface of this brown-black rot is shiny, and the diagnostic character of dark mycelial
strands can be seen with the aid of a microscope.
The fungus that causes take-all persists in infested wheat debris and on infected wheat
plants. Roots of the next crop become infected when they grow through soil near the
infested debris. The fungus initially colonizes the roots of the young wheat plants before
colonizing the crowns. If this root infection takes place in the fall or early spring then
the disease is much more severe. Initial infection and colonization are favored by
moderate temperatures (50 degree to 70 degree F) with adequate moisture.
| Disease Management Practices | Foliar Diseases | Seed and Seedling Diseases | Root and Crown Diseases | Head Diseases | Virus Diseases |
