Matt from Wilmington, Nc writes
If safe, how to formulate mixture for backpack sprayer.
Yes, Crystal Blue Copper Sulfate can be used to kill lichen/algae on oak trees. You would use it at a rate of 8 oz. per 3 gallons of water per the product manufacturer. They also recommend mixing in warm water so the product can disolve the best.
Answer last updated on: 10/28/2016