Using Copper Sulfate As A Fungicide

29 Mar 2011

For many years, copper sulfate solutions have been used as part of a fungicide mixture on trees, shrubs and grapevines. It is very effective against fungi, algae, bacteria and viruses. However, there are some guidelines that need to be followed in order to use this product safely & effectively.

The mixing formula is one of the critical points. The traditional Bordeaux mix includes copper sulfate, hydrated lime and water. The copper sulfate and hydrated lime should be mixed into the water and dissolved completely. Copper sulfate should be mixed into the water first, dissolved, and then the hydrated lime may be added. The ratio of the ingredients should be:

3 tablespoons of copper sulfate with

3 tablespoons of hydrated lime into

1 gallon of water

The formula can also be expressed as 10:10:100 for larger mixes. This would be as follows:

10 pounds of copper sulfate with

10 pounds of hydrated lime into

100 gallons of water

Another consideration to reflect on is the timing. Because of the “burning” effect of copper sulfate, application should be done before leaf emergence in the spring or after leaf drop in the fall to insure that leaves are not damaged by the copper sulfate. If the solution is desired for application after dormancy has broken, use a 1:1:100 to avoid damaging the leaves. This lighter dose is as follows:

1 pound of copper sulfate with

1 pound of hydrated lime into

100 gallons of water

Hopefully this clears up any confusion regarding using copper sulfate as a fungicide on trees, shrubs and grape vines. For additional information on Sanco products contact us.