Copper oxychloride (Blue Copper)

Copper oxychloride 50% WP is an inorganic contact fungicide and bactericide registered with CIBRC for use across paddy, citrus, chilli, potato, tomato, grapes, cardamom and coffee. It is sold under brand names including Blue Copper, Crystal Blue Copper, Fytolan and Cuprina.

Composition / Active ingredient

Active ingredient: Copper oxychloride [Cu₂Cl(OH)₃] containing ~50% metallic copper
Formulation: 50% WP (wettable powder)
Chemical class: Inorganic copper salt

Mode of action

Copper oxychloride slowly releases cupric ions (Cu²⁺) on hydration. The Cu²⁺ ions denature fungal and bacterial proteins by binding to sulphydryl and carboxyl groups, disrupting cell membranes and inhibiting spore germination. It is a multi-site contact protectant — FRAC group M01 — with very low resistance risk because it attacks many enzymes simultaneously.

Target use and dose

CIBRC-registered diseases include early and late blight (potato, tomato), downy mildew (grape), leaf spot, citrus canker, fruit rot, damping-off and bacterial leaf blight (BLB) of paddy. Standard applications:

Foliar spray: 2.5 g/L water (about 500 g/acre); a 2 g/L spray is sometimes used as a yard / threshing-floor disinfectant
Drench: 500 g/acre for soil-borne damping off
Chilli pod rot: 600 g/acre as an alternative to mancozeb
Mango wound dressing: alternative to fresh Bordeaux Paste Orchard Wounds when paste is unavailable

For BLB in paddy, copper oxychloride is tank-mixed with Streptocycline (200 g + 50 g per acre, respectively) for synergistic bacterial-disease cover.

Safety and regulatory status

Copper accumulates in soil over years of continuous use; long-term repeated application in orchards and vineyards can suppress soil microbial activity. Phytotoxicity may occur in sensitive crops (cucurbits, tomato seedlings) under cool wet conditions. Re-entry intervals are minimal due to the low acute toxicity.

References

Crystal Blue Copper 50% WP. Cultree.
Blue Copper Fungicide. BigHaat.