Question
I had a large wound on a Citrus (orange) tree where a limb broke off late last year. It was coated with copper sulfate by a local person. Now it looks as if the tree is dying. Would the copper sulfate cause this. The tree is only 8 years old. Fruit was very small this year. last year the tree was beautiful

Answer
Hi Bob, I do not cover the wounds of my trees.  I checked around and this is what I found, hope it helps. Seeing the way to make the solution may help to know if it was made properly, so that your question may be answered.  

The copper sulphate should first be dissolved in the water, which should be done as follows: Place the copper sulphate in an earthen or wooden vessel (do not use metal), and pour on the water occasionally until the blue crystals are dissolved. Slake the lime in 3 or 4 gallons of water; stir well, and when cooled off, strain through a fine sieve or cheese cloth into the vessel prepared for the mixture. The copper sulphate solution should always be poured into the lime. Do this carefully, that nothing may pass through the strainer which might stop up the nozzle of the sprayer. Add sufficient water to make 5O gallons of solution, and it is ready for use. Then to this add one quart of any kind of molasses, which will make it more adhesive; then dissolve to a pasty substance one-quarter pound of Paris green and add to above. mixing all thoroughly together. This is an efficacious mixture and one that can be used advantageously at all seasons for spraying.

The first spraying should be done in the early Spring, just as the buds begin to swell; the second spraying as soon as the blossoms begin to fall. This is the most important spray of all, its principal purpose being, of course, to destroy the codlin moth, and in addition it is intended to have it cope with any other insects, or fungous diseases. It is also desirable as well as beneficial to make a third spraying about two weeks after the second. Should the leaves of your trees show rust or mildew at any time, spray at once with the Bordeaux Mixture (without the addition of the Paris green). The spray can be applied to the trees so that it may fall upon the limbs, leaves and fruit. The style of spray pump to use will depend entirely on circumstances and your requirements. For large orchard spraying the barrel pump will be the best and most economical, while for scattering small plantings and for general purposes on the private place or small diversified fruit farm, the knapsack sprayer would be the most desirable and satisfactory.   kathy