Untitled - International Rice Research Institute

Fig. 28. Occurrence of bakanae (Ou 1985, Agarwal and Mathur 1988, EPPO 1997).
c. Location on seed
F. moniliforme is most likely observed on the entire
rice seed (about 57%) (Fig. 31).
Microscopic character
a. Mycelia—hyaline, septated (Fig. 30d).
b. Microconidiophore—single, lateral, subulate
phialides formed from aerial hyphae, tapering
toward the apex (Fig. 30e).
c. Macroconidiophore—consisting of a basal cell
bearing 2–3 phialides that produce macroconidia.
d. Microconidia—hyaline, fusiform, ovate or clavate;
slightly flattened at both ends; one- or twocelled;
more or less agglutinated in chains, and
remain joined or cut off in false heads (Fig. 30f).
Measurements: 2.53–16.33 µ × 2.30–5.75 µ
(PDA); 5.06–14.26 µ × 1.61–4.83 µ (PSA); and
4.60–10.35 µ × 1.61–4.83 µ (OA, oatmeal agar).
e. Macroconidia—hyaline, inequilaterally fusoid;
slightly sickle-shaped or almost straight; thinwalled;
narrowed at both ends, occasionally bent
into a hook at the apex and with a distinct foot cell
at the base; 3–5 septate, usually 3 septate, rarely
6–7 septate; formed in salmon orange
sporodochia or pionnotes (Fig. 30g). Measurements:
18.86–40.71 µ × 2.76–4.60 µ (PDA);
16.10–35.42 µ × 2.07–4.60 µ (PSA); and 21.39–
39.56 µ × 2.53–4.60 µ (OA).
Colony characters on culture media (Fig. 32)
Colonies on PDA at ART (28–30 °C) grow moderately
fast and attain a 5.20-cm diam in 5 d. They are
slightly zonated; floccose to slightly felted, and become
powdery with age; white tinged with pink at the
center. The colony appearance on the reverse side of
the agar plate is slightly zonated and white with a purplish
center. At 21 °C under alternating 12-h NUV
light and 12-h darkness, colonies grow slowly and attain
a 3.72-cm diam in 5 d. They are slightly zonated,
cottony to slightly felted with submerged advancing
margins and pink. The colony on the reverse of the
agar plate appears slightly zonated and dark pink and
light toward the margin. At 28 °C under alternating 12-
h fluorescent light and 12-h darkness, colonies grow
moderately fast and attain a 5.10-cm diam in 5 d.
They are zonated and appear cottony to slightly felted
with sinuate margins, purplish at the center and light
outward. Saltation of colonies is occasionally observed
in some plates. The colony on the reverse side
of the agar plate is zonated and purple and light purple
outward.
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