Copper Spray
A broad-spectrum copper-based fungicide and bactericide that protects against a wide range of fungal and bacterial diseases on vegetables, fruit, and ornamentals.
What it is
Copper-based fungicides are produced from naturally occurring copper salts, including copper hydroxide, copper oxychloride, and copper octanoate. Copper has been used as a plant protectant since the late 1800s and remains one of the most widely used tools in organic disease management. Most formulations are certified for organic use, though copper accumulation in soil is a recognised long-term concern.
What it does
Copper ions released on wet plant surfaces are toxic to fungal spores and bacterial cells, preventing germination and colonisation. Copper acts as a surface protectant rather than a systemic treatment, so it must be present on the plant surface before or very shortly after infection events. It does not cure established infections but prevents their spread.
When to use
Apply preventively before expected wet or humid weather that favours disease spread, or immediately after identifying early infection. For fire blight, apply at early bloom when temperatures are above 60°F and rain is forecast. For blight and downy mildew, begin applications at first symptoms or when conditions are persistently wet.
When not to use
Do not apply copper during bloom when pollinators are foraging, as copper is toxic to bees at high concentrations. Avoid repeated applications in the same season beyond the label-recommended maximum to limit soil copper accumulation. Some plants, including certain stone fruit cultivars, may show copper sensitivity - always check before use.
How to apply
- 1
Select an appropriate copper formulation (copper hydroxide, copper oxychloride, or copper octanoate) and dilute to the label-specified rate.
- 2
Check the weather forecast. Apply when no rain is expected for at least 4 hours to allow the spray to dry and bond to the leaf surface.
- 3
Spray all plant surfaces thoroughly, including leaf undersides, stems, and fruit where applicable.
- 4
Pay particular attention to new growth and recently opened flowers or wounds where infection is most likely to occur.
- 5
Repeat every 7 - 14 days during wet, disease-conducive weather, or after each significant rain event washes off the residue.
Used for
Garden, by Willowbottom recommends only organic, wildlife-friendly solutions. No synthetic pesticides, no harmful chemicals - ever.