A Handbook of Rice Seedborne Fungi TW Mew and P ... - IRRI books

Fig. 28. Occurrence of bakanae (Ou 1985, Agarwal and Mathur 1988, EPPO 1997).c. Location on seedF. moniliforme is most likely observed on the entirerice seed (about 57%) (Fig. 31).Microscopic charactera. Mycelia—hyaline, septated (Fig. 30d).b. Microconidiophore—single, lateral, subulatephialides formed from aerial hyphae, taperingtoward the apex (Fig. 30e).c. Macroconidiophore—consisting of a basal cellbearing 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, andremain 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); and4.60–10.35 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 bentinto a hook at the apex and with a distinct foot cellat the base; 3–5 septate, usually 3 septate, rarely6–7 septate; formed in salmon orangesporodochia 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 moderatelyfast and attain a 5.20-cm diam in 5 d. They areslightly zonated; floccose to slightly felted, and becomepowdery with age; white tinged with pink at thecenter. The colony appearance on the reverse side ofthe agar plate is slightly zonated and white with a purplishcenter. At 21 °C under alternating 12-h NUVlight and 12-h darkness, colonies grow slowly and attaina 3.72-cm diam in 5 d. They are slightly zonated,cottony to slightly felted with submerged advancingmargins and pink. The colony on the reverse of theagar plate appears slightly zonated and dark pink andlight toward the margin. At 28 °C under alternating 12-h fluorescent light and 12-h darkness, colonies growmoderately fast and attain a 5.10-cm diam in 5 d.They are zonated and appear cottony to slightly feltedwith sinuate margins, purplish at the center and lightoutward. Saltation of colonies is occasionally observedin some plates. The colony on the reverse sideof the agar plate is zonated and purple and light purpleoutward.32