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SCAB OF WHEAT AND BARLEY
by
Eric G. Sharvelle
Botany and Plant Pathology
Mimeograph No: B.P. 23
Purdue Univ. Agr. Exp. Sta.
Every year around the middle of June many wheat growers in Indiana become concerned
with a diseased condition of wheat and barley heads generally referred to as HScabw0 This
is a disease that occurs in varying degree in most seasons. It may also attack oats.
ljhat does scab look like?
The most conspicuous symptom of scab on wheat and barley is the premature ripening
of one or more spikelets giving the head a bleached or whitened appearance. The entire
head is not generally affected. In some cases only a few spikelets are involved, while
in other instances the top half of the head may be affected, or the entire spike in rare
instances may become infected with scab. When the grain is in the dough stage scab-
infected spikelets turn light yellow in color and stand out in sharp contrast with the
healthy green color or normal spikelets. As the wheat ripens the infected portion of the
head turns white and in wet weather a light pink or salmon color appears at the base of
infected spikelets or along the edge of the chaff. Heads infected with scab occur at
random scattered throughout the field and generally are not confined to localised areas
of the field.
The grain produced from scab infected portions of the head is badly shrunken and
shrivelled, and has a noticeable rough or flaky coat generally accompanied by the
characteristic pink or salmon-red color. At harvest time the spikelets infected with
scab become speckled with small, blue-black dots.
The scab disease of wheat and barley also causes a seedling blight in addition to
resulting in a blasting of portions of maturing wheat and barley heads. If wheat from
fields infected with scab is used as seed, poor stands generally occur as a result of
seedling blight caused by the scab fungus that persists on grain from infected heads.
Seedlings affected by scab are stunted, yellow, and the root system is generally reddish-
brown in color and may become covered with a mass of gray or pinkish mold. The root
system of wheat seedlings infected with seedling blight may be destroyed partially or
completely and the seedlings either die or fail to stool properly producing a single
stem with a small shrivelled head. The symptoms of scab on barley are identical with
those described for wheat.

What causes scab of wheat and barley?
Scab of wheat and barley is caused by the fungus Gibberella saubinetti. The fungus