Copper spray has been used to treat fruit trees for many years and is considered a staple to prevent disease. Most forms, such as copper sulfate, are approved for organic growers and can be used on your organic fruit trees. Copper sprays are safe for most orchard applications when directions are followed.
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Ingredients and Effectiveness
Copper fungicides contain various additives and inert ingredients, but it is the copper that does the work .The letters MCE on the product label stand for “metallic copper equivalent” and refer to the amount of actual metalic copper in the product. Different products will contain varying amounts. Generally speaking, the more copper in the mix the better it will work to prevent diseases that attack fruit trees. However, weather conditions also play a role in the usefulness of copper because it can be washed off by the rain .
Copper spray is more effective at preventing disease if applied before a tree becomes infected. Common fruit tree diseases, such as brown rot, leaf curl, bacterial canker and blight, respond well to a spraying program that includes copper. To treat these diseases, all tree surfaces, including the underside of leaves, all branches and the entire trunk, must be evenly sprayed.
Know when and how often to spray. Some trees are sensitive to copper, and spraying while the trees are still dormant will ensure that you don't damage tender new leaves or cause spots on the fruit. Although copper is used on peach, nectarine and apricot trees, extra care should be taken with these varieties. Read labels and use the lowest amount of copper that is effective on your particular types of tree.
Although copper is organic, it is still dangerous in high concentrations to people and animals. Care should be taken to protect your skin and eyes when using copper spray, just as you would with any other household chemical. Read the label of the product you will be using and then carefully measure and apply. Try to do your spraying on a calm day. This will ensure that most of the copper goes on the tree and not on you and the surrounding area. Copper is especially toxic to fish, so be extra careful when spraying near ponds.
Copper sprays are an effective alternative to man-made synthetic chemicals, and when used properly are just as effective. Start spraying early in the season and keep to the schedule recommended by the spray's manufacturer. If copper is not washed off by rain or the sprinkler, it can remain on leaves for as long as two weeks. At that point, it may need to be reapplied. Copper can accumulate in the soil, so reapply only as often as specified and use no more than necessary.