Copper Oxychloride vs. Copper Sulphate: Which Fungicide Wins for Crops?
Copper Oxychloride is a green, insoluble copper salt used as a protective fungicide, forming a shield on plant surfaces. Copper Sulphate is a blue, soluble crystal that acts as both fungicide and nutrient, entering plant tissues to kill spores.
Walk any farm shop and you’ll see “copper” on dozens of labels; growers grab whichever jug is cheaper, then wonder why one mix clogs sprayers while the other burns leaves. The colour and solubility tricks them into thinking the two are interchangeable.
Key Differences
Copper Oxychloride stays on the leaf as a solid barrier, resisting wash-off and lasting 10–14 days. Copper Sulphate dissolves, moves systemically, and is quickly diluted by rain, needing repeat sprays.
Which One Should You Choose?
Choose Copper Oxychloride for long-lasting, rain-resistant protection on tomatoes, vines, and potatoes. Pick Copper Sulphate when you want rapid knock-down plus a trace-copper feed for citrus or cocoa.
Can I tank-mix both?
No; the mix forms gritty precipitates that block nozzles and reduce efficacy.
Is Copper Oxychloride safer for bees?
Yes; its low solubility keeps residues on foliage, minimising bee exposure.
How much is too much copper per season?
Stay below 4 kg metallic copper per hectare per year to avoid soil accumulation.