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Tricyclazole

Tricyclazole is a systemic fungicide registered in India in 75% WP formulation under brand names including Trick (Crystal), Tric (Krishi Rasayan), Blast and Beam. It is the standard preventive treatment for rice blast (Magnaporthe oryzae) in Indian paddy.

Composition / Active ingredient

  • Active ingredient: Tricyclazole
  • Formulation: 75% WP (wettable powder)
  • Chemical class: Benzo-thiadiazole / triazolobenzothiazole

Mode of action

Tricyclazole inhibits scytalone dehydratase, an enzyme in the fungal dihydroxynaphthalene (DHN) melanin biosynthesis pathway. Without melanin, the appressorium (the penetration structure formed by Magnaporthe oryzae) cannot generate the high turgor pressure needed to mechanically pierce the rice cuticle. The result is a fully effective preventive action without killing established fungal mycelium — the fungus is rendered unable to infect new tissue. FRAC group 16.1 (melanin biosynthesis inhibitor, reductase pathway, MBI-R).

Because the mode is preventive, application timing relative to disease pressure is critical: it must be applied before or at the earliest signs of infection.

Target use and dose

CIBRC-registered for rice blast control:

  • Leaf blast (early vegetative stage)
  • Node blast (tillering)
  • Neck blast / panicle blast (most damaging — at heading and grain-filling)

Standard dose is 120 g/acre (0.6 g/L) at booting / late booting and again at heading. Tricyclazole is often combined with strobilurins for full-spectrum protection, e.g. with picoxystrobin in Picoxystrobin Tricyclazole Galileo Sensa.

Safety and regulatory status

The EU MRL for tricyclazole on rice is 0.01 mg/kg — effectively the limit of detection — which severely restricts export of Indian basmati rice if tricyclazole has been used. Growers producing for export markets must use alternative blast fungicides (Tebuconazole Trifloxystrobin Nativo, Azoxystrobin Difenoconazole) or comply with strict pre-harvest interval discipline.

See also: Picoxystrobin Tricyclazole Galileo Sensa, Nativo Fungicide, Tebuconazole Trifloxystrobin Nativo, Azoxystrobin Difenoconazole, Mancozeb Carbendazim Saaf.

References

  1. Tricyclazole 75% WP. Peptech Biosciences.
  2. Flock Fungicide — Tricyclazole 75 WP. BigHaat.