How to Use Copper Sulfate As a Fungicide

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Things You'll Need

  • Copper sulfate

  • Water

  • Hydrated lime

  • Pump-up sprayer

  • Long pants

  • Long-sleeved shirt

  • Safety glasses


The best time to spay a plant with a copper sulfate fungicide is before leaf out in the spring or after leaf drop in the fall to prevent damaging the leaves. However, if you must spray during the growing season, use a diluted mixture of the fungicide as follows: 1/3 tbsp. copper sulfate to 1/3 tbsp. hydrated lime to 1 gallon of water.


Wear long pants, long-sleeved shirts and safety glasses when spaying the fungicide. Apply on a calm day to prevent overspray to undesirable areas. Promptly remove and wash all clothing when finished to prevent harm as the copper sulfate can be toxic.

Since fungi cannot make food of their own, they steal nutrients from plants. During this process they attack and kill plant cells, which leads to the decline and eventually the death of the plant, if the fungi is left uncontrolled. Fungi thrive in moist environments -- some in cold and moist environments and some in warm and moist environments. If fungi are noted on your plants, use copper sulfate to kill them. The proper mixture is crucial as too much is also toxic to plants.


Step 1

Prepare your copper sulfate solution. Add 3 tbsp. of copper sulfate to 1 gallon of water. Stir the mixture until completely dissolved.

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Step 2

Add 3 tbsp. of hydrated lime into the mixture and once again stir until completely dissolved.

Step 3

Pour the mixture into a pump-up sprayer. Spray the areas of the plant infected with the fungi until fully coated. Refrain from spraying to healthy parts of the plant.

Step 4

Repeat the process in two weeks if the plant is still infected with fungi.