Untitled - International Rice Research Institute

They are feathery to slightly fluffy, zonated with
even to slightly uneven margins, and alternating olive
yellow and dark olive with 5-mm light yellow margins.
On the reverse side of the agar plate, the colony
appears azonated to slightly zonated, black, and becomes
dark greenish gray to olive black toward the
margin.
Colonies on MEA at ART (28–30 °C) grow very
slowly and attain a 2.29-cm diam in 5 d. Colonies are
scanty with fluffy aerial mycelia, azonated with uneven
margins, and olive gray with grayish yellow
aerial mycelia. The colony appears azonated and
olive black on the reverse side of the agar plate. At
21 °C under alternating 12-h NUV light and 12-h
darkness, colonies are restricted in growth and attain
a 1.71-cm diam in 5 d. They are azonated with
crenate margins, velvety, and olive black with white
to dark olive mycelial tufts. The colony appears zonated
and olive black to black on the reverse side of
the agar plate. At 28 °C under alternating 12-h fluorescent
light and 12-h darkness, colonies are restricted
in growth and attain a 1.71-cm diam in 5 d.
They are azonated with crenate margins, velvety
with slightly fluffy centers, and dark greenish gray to
olive black. The colony on the reverse side of the
agar plate appears azonated and black.
Cercospora janseana (Racib.) Const.
syn. Cercospora oryzae Miyake
teleomorph: Sphaerulina oryzina Hara
Disease caused: narrow brown leaf spot
a. Symptoms
Short, linear, brown lesions most common on
leaves but also occur on leaf sheaths, pedicels,
and glumes.
b. Occurrence/distribution
The disease has worldwide distribution (Fig. 14).
c. Disease history
The disease was first observed in North America
before 1910 but its detailed description was re-
Fig. 14. Occurrence of narrow brown leaf spot (Ou 1985, Agarwal and Mathur 1988, EPPO 1997).
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