Chemical Class and Melanin Biosynthesis Inhibition
Tricyclazole belongs to the triazolobenzothiazole chemical class (FRAC Group 16.5 - Melanin Biosynthesis Inhibitors / MBI-D). It specifically inhibits the enzyme 1,3,8-trihydroxynaphthalene (THN) reductase involved in the fungal melanin pathway.
Without melanin accumulation, fungal appressoria fail to melanize and cannot build the turgor pressure needed to mechanically penetrate the rice leaf cuticle. This halts infection before the blast pathogen can establish inside plant cells.
- FRAC Group 16.5 Mode of Action: Prevents appressorial melanization and physical host cell penetration.
- Rapid Systemic Absorption: Absorbed by leaves and roots within 30 minutes, translocating acropetally to protect newly expanding leaves.
- High Rainfastness: Excellent adherence ensures it remains fully active even during continuous monsoon rainfall.
Target Blast Phases in Irrigated Rice
Rice blast caused by the fungus Magnaporthe oryzae (Pyricularia oryzae) is capable of causing catastrophic crop losses. Sivic is specialized for controlling all three manifestations of blast in paddy ecosystems.
It protects seedlings from nursery blast, stops spindle-shaped lesions during leaf blast, and shields the panicle neck from neck blast and node blast, which cause empty, chaffy grain heads.
- Leaf Blast Defense: Curbs diamond-shaped brown lesions with grey centers on active foliage.
- Neck Blast Prevention: Applied prior to panicle emergence to prevent rotting at the base of the panicle neck.
- Node Blast Protection: Prevents blackening and breakage of stem nodes under dense fertilizer regimes.
Application Timing and Spray Guidelines
Because Tricyclazole acts primarily by preventing fungal cuticular penetration, timing is critical. Apply Sivic preventively at the initial appearance of blast spots on lower leaves or as a boot-leaf spray prior to panicle emergence.
Maintain adequate spray volume using calibrated knapsack sprayers fitted with hollow cone nozzles to ensure thorough coverage of both leaf blades and sheaths.
- Preventive Booting Spray: Spray just before panicle emergence to protect against devastating neck blast.
- Nursery Application: Can be applied to seedling nursery beds 5 to 7 days before uprooting and transplanting.
- Pre-Harvest Interval (PHI): Observe the statutory harvest waiting window specified on the registered product packaging.
Official source
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Central Insecticides Board & Registration Committee (CIBRC) ↗Related on KisanPe
Common questions
What is the technical ingredient in Sivic fungicide?
Sivic contains Tricyclazole 75% WP (Wettable Powder), a systemic melanin biosynthesis inhibitor fungicide.
How does Tricyclazole prevent rice blast infection?
It inhibits melanin synthesis in fungal appressoria, preventing the pathogen from generating the mechanical pressure required to pierce the leaf cuticle.
When is the most critical time to spray Sivic against neck blast?
The most effective time is at the late boot stage to early panicle heading (5% to 10% flowering) before fungal spores infect the panicle neck.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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