anthracnose fungal disease, how to spray #732774 - Ask Extension

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anthracnose fungal disease, how to spray #732774

Asked October 31, 2020, 12:10 PM EDT

I have mature apple trees in my back yard severely affected with anthracnose. I know I will have to prune the trees severely and spray with copper. I know that copper solutions are very expensive. I know that copper phosphate is cheaper but you have to spray it as an emulsion as it will not dissolve in water. can you spray an emulsion in your sprayer just like a solution. or does it plug up your sprayer. What concentration do you use and how do you measure it out?

Washington County Oregon

Expert Response

Hi I'm not familiar with that formulation used as a fungicide. Copper ammonium, copper hydroxide, copper oxide, copper oxychloride, and copper sulfate are the normal forms used in copper products formulated for orchard use. Some emulsions are just fine in a sprayer, typically an emulsifying agent is used either in the product or it is added to the tank during mixing with water. For example, many insecticides come as EC formulations which stands for emulsified concentrate and these have an oil, a solvent and an emulsifier and they mix with water. Oil sprays are highly useful in orchard pest management and these typically contain emulsifiers to allow them to mix with water. Highly viscous emulsions can sometimes result from improper mixing of products in the spray tank and these spell big trouble for orchard sprayers. Mayonnaise consistency is problematic.
Nik Wiman Replied November 06, 2020, 3:25 PM EST

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