COPPER SPRAYING FOR TREES
Fungal diseases plague several types of Olive and fruit trees. Many of the products that are effective against these diseases are for professional use only. One group of products that is readily available and effective against fungal diseases is fixed copper spray. These products can save a crop, and sometimes an entire tree, if used properly.
Copper spray is effective against a number of diseases that attack fruit trees. Peach leaf curl affects the shoots, flowers, foliage and fruit of peaches and nectarines. If left untreated for several years, you may lose the tree. Fire blight primarily attacks pome fruit trees, such as apples and pears, although it can affect other plants. Leaves and young twigs take on a scorched appearance, and the disease travels down the stems if the affected areas aren't pruned away. Brown rot causes the collapse of the flowers on a number of fruit trees, and a resulting loss of fruit. Bacterial canker is a citrus disease that causes fruit and leaf spots.
The active ingredient in copper sprays is listed on the label as metallic copper equivalent. Products with higher percentages of MCE are more effective. Other ingredients in the spray help the product stick to the sprayed surface and spread. The University of California Integrated Pest Management Program website warns that some copper sprays don't contain enough fixed copper to control leaf curl. The product you choose to control this disease should contain 50 percent copper. Copper spray should be applied thoroughly. Spray the tree until the product drips from the leaves and stems. To treat fire blight, use a weaker solution every few days until the end of the bloom season.
WHEN TO SPRAY
Copper spray is usually applied during the dormant season. For diseases that affect the blossoms and young fruit, apply copper sprays every few days to every two weeks, depending upon the disease and the fruit affected. This can result in as many as 17 applications over a season for some fruit. The package label is your best source of information about when and how often to spray. Heavy rains can rinse the product from the tree, so use it when you aren't expecting rain.
Using copper sprays over several seasons can cause a buildup of copper in the soil. The buildup eventually becomes toxic to soil organisms, including earthworms. It is also harmful to aquatic species if it moves into bodies of water. Skin exposure can cause pain and itching, and some people become sensitized and experience allergic reactions with repeated use. Wear protective clothing when using copper sprays avoid eye contact by wearing goggles. As with all garden chemicals, store copper sprays in their original container and out of the reach of children.