THILAGAVATHI R., DINESH KUMAR R., SURESH KUMAR R. AND JAHANMOHAN K. R.
Department of Plant Pathology, Department of Agricultural Economics Tamil Nadu Agricultural University, Coimbatore (Tamil Nadu), India
District Livestock Farm, Naduvur, Thanjavur District (Tamil Nadu), India
*(e-mail: thilagavathi.r@tnau.ac.in)
(Received : 16 July 2025; Accepted : 30 July 2025)
SUMMARY
The fodder crops were found to have blast disease caused by the fungus Magnaporthe sp. at the District Livestock Farm in Naduvur, Thanjavur District, during June, 2024. The leaves of the hybrid Napier cultivars, such as CO 4, CO 5, IGFRI 6, and IGFRI 10, exhibited spindle-shaped necrotic gray lesions with distinct brown margins. Blighted leaves turn brown and dry, which can be easily observed from a distance. The middle and lower leaves of the hybrid Napier cultivars were affected by blast disease. They showed a Percent Disease Index (PDI) ranging from 18.7 to 43.6, in which the cultivar CO 4 recorded higher PDI compared to other cultivars. Under microscopic examination, the lesions clearly revealed asexual conidia that were pyriform-shaped, hyaline, two-septate (three- celled), with a hilum at the base, tapering towards the tip. Conidiophores were also observed. The liquid formulation of TNAU Bacillus subtilis strain Bbv 57 was sprayed all cultivars and monitored for blast disease. The results revealed that hybrid Napier cultivars treated with Bacillus exhibited a significantly reduced incidence of blast (PDI: 8.2 to 12.3). However, plants in the untreated control plots showed a maximum PDI of up to 62.4, especially in the hybrid Napier cultivar CO 4. Increased foliage yield in the range of 74.25 to 75.3 t/ha was observed in the treated plots compared to untreated plots which showed low yield of 39.25 to 56.0 t/ha. Therefore, blast disease on forage crops can be effectively managed through foliar application of B. subtilis.
Key words: B. subtilis, blast disease, fodder, hybrid napier and management