Plant Diseases
Wheat Diseases in Arkansas
Take-all
Take-all, caused by the fungus, Gaeumannomyces graminis variety tritici, can
be a severe problem in some Arkansas fields. Symptoms first show in the spring
as stunted chlorotic plants, but these usually are overlooked. The most obvious
symptoms occur during the grain-filling period when infected plants die
prematurely and turn bleached white. Roots, crowns and lower stems of these
plants will have a characteristic shiny black color due to growth of the
take-all fungus. These dead plants usually occur in irregular patches that show
up in the same areas of a field and expand each year that wheat is grown.
Take-all is favored by continuous cropping of wheat, soil pH above 6.0, ample
soil moisture early in the spring and drought stress during the grain-fill
period.
The pathogen survives in root and crown tissue from previous crops, and
infection can occur throughout the growing season. Crop rotation for two years
out of wheat and tillage to allow decomposition of this infested crop debris is
one means of control. Oats and summer crops normally grown in Arkansas are not
affected by take-all. Volunteer wheat and grassy weeds may perpetuate the
take-all fungus, and these should be controlled between wheat crops.
A process called "take-all decline" can occur after successive wheat crops,
especially on acid soil. Take All decline is a form of biological control where
soil microorganisms antagonistic to the take-all fungus increase over time. A
field must be kept in continuous wheat to take advantage of take-all decline.
Baytan seed treatment is not effective against take all under Arkansas
conditions.
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