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Controlling Tree Fungus

14 Mar 2019

Copper spray has been used to treat fruit trees for many years and is considered a method to prevent disease.  Most forms, such as Sanco Industries, Inc.  Copper Sulfate Smart Crystal, 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.

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 metallic copper in the product. Sanco Industries, Inc. Copper Sulfate Smart Crystals has 25% MCE.  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.

To treat tree fungus you need to make a Bordeaux mixture which is a combination of copper sulfate, lime, and water.   This Bordeaux mixture is an effective fungicide and bactericide that has been used for decades to control diseases of fruit and nut trees, vine fruits, and ornamental plants. These natural minerals, when mixed in the correct order, provide long-lasting protection to plants against diseases.

Although there are many formulas for preparing Bordeaux mixture, generally a ratio of 10-10-100 works well for many disease-causing pathogens.

A more convenient amount for the home gardener would be a 1-gallon mixture of 10-10-100 Bordeaux, which would contain 1/10th of a pound of each of the dry ingredients, which would be 3 tablespoons of copper sulfate and 3 tablespoons of dry hydrated lime in 1 gallon of water.

When applying the first application of the Bordeaux mixture you will want to do so in early spring before the tree buds open.  It’s best to spray on calm day when no rain is in the forecast for 24 to 48 hours.  Wear gloves and spray the entire tree (trunk and branches).  You can also apply in fall and winter to manage Fire blight on pears and apples,  Leaf curl and shot hole on peaches and nectarines,  Downy mildew and powdery mildew on grapes,  Peacock spot on olives,  Walnut blight on walnut  and Black spot on roses.

For more information on Sanco’s copper sulfate contact us.