Studies on Pearl Millet Blast Caused by Pyricularia grisea (Cooke) Sacc. In Northern Karnataka
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Date
2013
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UAS, Dharwad
Abstract
Pearl millet [Pennisetum glaucum(L.)R.Br.] one of the common millets grown as a
nutrient-rich food source for human and as a fodder crop for livestock. Among the several
diseases, the blast caused by Pyricularia grisea (Cooke) Sacc. has emerged as a serious
disease affecting both forage and grain production in pearl millet resulting economic loss.
In the present investigation, the roving survey carried out during kharif 2012 revealed
that, the highest disease intensity was observed in Koppal district (76.1%) while least was in
Bijapur (31.1%) district. The disease appeared as small, water soaked, later developed as
spindle shaped spots with grayish white center with a brown margin. Morphologically
Pyricularia grisea (Cooke) Sacc., produced hyaline to pale olive, pyriform conidia, 3-celled
with 2–septa and measured 17.5–24.0 x 6.5–8.0 μm.
Cultural studies indicated carrot and Czapeck's agar (9.0 cm each) among the solid
media and Richard's medium (393.0 mg) among different liquid media supported
significantly highest mycelial growth while maximum growth of fungus reached on 14th day
of incubation.
Variability studies of P. grisea isolates revealed, maltose and sucrose (396.3 mg each)
as the best carbon sources while sodium nitrate (407.1 mg) supported significant maximum
growth among the nitrogen sources. Isolates Pg4 (Ilakal) and Pg3 (Sindagi) recorded
significantly maximum mycelial growth at 250C whereas temperature range of 20 - 300C and
pH range of 6.5 to 7.5 was favourable for growth of all the isolates under study.
In vitro bioassay revealed mancozeb75WP (93.30%), captan70+ hexaconazole5 75
WP (93.17%) among the non-systemics and tricyclazole75WP (87.78%) among the systemic
fungicides significantly inhibited pathogen. Among botanicals commercial-product; Soldier
(71.54%) and tulasi (70.93%) significantly inhibited P. grisea growth while no bioagents
were effective. All the 24 genotypes screened were susceptible (Grade 5-6) to highly
susceptible (Grade 7-9) to P. grisea under natural infection conditions.