Wheat Diseases and Pests - Wheat Doctor - CIMMYT

Bacterial Black Chaff
and Bacterial Stripe
Xanthornonas carnpestris pv. translucens
Syn. X. translucens, X. translucens f.sp. undulosa,
X. campestris pv. undulosa
Symptoms: Black chaff and bacterial stripe are
both caused by the same organism; the site and
extent of the symptoms depends on the strain of
the bacterium, the affected cultivar and
environmental conditions. "Bacterial black chaff"
occurs primarily on the glumes (48); "bacterial
stripe" occurs primarily on the leaves and/or leaf
sheaths (49). Initial symptoms are narrow
chlorotic lesions or stripes that have a watersoaked
appearance; droplets of sticky yellowish
exudate may appear with extended periods of rain
or dew (50). The exudate dries to form crusty
droplets or a translucent film on the surface of
affected tissues. The film may crack and give a
scaly appearance. If infection occurs early in the
crop cycle, the spike may be infected, resulting in
sterility; when the disease is severe, entire leaves
or spikes may be killed.
Development: The bacterium can be seed borne
and persists on crop residues in the soil, tolerating
warm as well as freezing temperatures. Free
moisture is required for infection and spread of the
disease. Infection occurs through stomata and
broken epidermal tissue. The disease is spread by
splashing rain, plant contact, and insects.
Hosts/Distribution: These diseases occur
worldwide on all small grain cereals and many
grasses.
Importance: Black chaff and bacterial stripe rarely
cause significant damage, even though symptoms
often may be extensive.