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Pinatubo oryzae Manandhar & Mew Disease caused: seed rot a. Symptoms Gray lesions on plumules. b. Occurrence/distribution Pinatubo oryzae is frequently encountered in rice seed grown in the Philippines and other countries occurring on both germinated and nongerminating seeds (Fig. 56). c. Disease history This fungus was previously identified as Verticillium cinnabarinum and re-identified as Pinatubo oryzae in 1996. It has been detected from rice seeds since 1982. It is highly probable that the organism was already present earlier but there are no literatures to document any efforts to identify the fungus. d. Importance in crop production This fungus is a rice grain pathogen. It is minor in importance to rice production. → Detection on seed a. Incubation period on blotter Using the blotter test, P. oryzae can be observed on rice seeds 5 d after incubation in NUV light at 21 °C. The detection frequency is about 25.2% on rice seeds coming from different regions. b. Habit character Aerial mycelia are sparse to abundant and white with loose and abundant branching. Conidia are borne terminally and arranged in a flower-like manner. Pionnotes present on the seed surface are wet and creamy to pink or they hang under a thin cover of aerial hyphae (Fig. 57 a-c). c. Location on seed P. oryzae is most often observed over the entire seed surface (about 46%) (Fig. 58). Microscopic character a. Mycelia—hyaline, septate (Fig. 57d). b. Conidiophore—simple or branched, short, septate with denticles at the terminal portion (Fig. 57e). c. Conidia—elongately oval, single- to 2-celled, very rarely 3-celled; pointed at the basal portion and rounded at the apical portion, hyaline (Fig. 57f). Measurements: 5.06–10.81 µ × 2.70–6.21 µ (PDA); 5.75–12.88 µ × 2.76–5.98 µ (PSA); and 5.75–11.73 µ × 2.53–5.06 µ (MEA). Colony characters on culture media (Fig. 59) Colonies on PDA at ART (28–30 °C) grow relatively fast and attain a 5.02-cm diam in 5 d. They are zonated with even margins, floccose, and reddish or- Fig. 56. Occurrence of Pinatubo oryzae on rice seed from different countries received at IRRI (IRRI-SHU unpublished data 1990-97). 51
a b → → → f e f c d Fig. 57. Habit character of Pinatubo oryzae Manandhar and Mew on (a) whole seed (12X), (b) sterile lemmas (50X), and (c) awn portion (50X). Photomicrograph of P. oryzae showing (d) mycelia, (e) conidiophore, and (f) conidia at 40X and stained with lactophenol blue. Observed frequency (%) 60 50 40 30 20 10 0 Sterile lemmas Awn Partition bet. lemma and palea Entire seed Lemma/ palea only or both Seed part Fig. 58. Observed frequency of Pinatubo oryzae occurrence on the seed. Fig. 59. Plate cultures of Pinatubo oryzae Manandhar and Mew showing colony growths on PDA, PSA, and MEA incubated at ART, 21 °C, and 28 °C at 15 d after inoculation. 52
Page 2 and 3:
Contents Foreword Preface v vi INTR
Page 4 and 5: Introduction The purpose of seed he
Page 6 and 7: Functions of seed health testing Se
Page 8 and 9: % infected seed lots 100 80 60 40 2
Page 10 and 11: Table 3. Pathogen profiles closely
Page 12 and 13: Table 4. Germination (%) of untreat
Page 14 and 15: Microorganisms associated with seed
Page 16 and 17: Identification of fungi detected on
Page 18 and 19: Detection frequency (%) 100 80 60 4
Page 20 and 21: moderately fast and attain a 4.32-c
Page 22 and 23: Detection frequency (%) 120 100 Eas
Page 24 and 25: They are feathery to slightly fluff
Page 26 and 27: Observed frequency (%) 120 100 80 6
Page 28 and 29: Frequency level (%) 120 100 East As
Page 30 and 31: a 4.90-cm diam in 5 d. They are eve
Page 32 and 33: Detection frequency (%) 90 80 East
Page 34 and 35: gray, becoming dark near the margin
Page 38 and 39: Sarocladium oryzae (Sawada) W. Gams
Page 40 and 41: a b c e f d f Fig. 35. Habit charac
Page 42 and 43: Fig. 38. Occurrence of black kernel
Page 44 and 45: a b d → → → e → f → f →
Page 46 and 47: d a b e → → → → → f c g h
Page 48 and 49: Fig. 46. Occurrence of minute leaf
Page 50 and 51: of the agar plate appears slightly
Page 52 and 53: Detection frequency (%) 120 100 Eas
Page 56 and 57: ange with orange. The pionnotes are
Page 60 and 61: Other fungi detected on rice seeds
Page 62 and 63: a b e c d Fig. 65. Habit character
Page 64 and 65: a d d b c Fig. 69. Habit character
Page 66 and 67: → → → a b f f e d e e c f Fig
Page 68 and 69: a b a Fig. 76. Habit character of F
Page 70 and 71: a b d c d e e Fig. 79. Habit charac
Page 72 and 73: a b c → → → d → Fig. 83. Ha
Page 74 and 75: → → → a b d c Fig. 86. Habit
Page 76 and 77: a b c Fig. 89. Habit character of P
Page 78 and 79: a b d c e Fig. 92. Habit character
Page 80 and 81: → → → → a b e f → c d Fig
Page 82 and 83: a b c d Fig. 100. Habit character o
Page 84 and 85: → → → → → → a → →
Page 86: Savary S, Willocquet L, Elazegui FA
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