Blackberry disease/pests

Asked June 14, 2018, 9:57 AM EDT

I recently put in about 60 ft of blackberry and raspberry plants. I noticed that several of my blackberry plants are having some difficulties. Some have lighter edges on the leaves, and others have orange "scabby" looking patches on them and look sickly. Wondering what the cause could be and what the recommendation for treatment would be. Thank you! 517-775-0280

Shiawassee County Michigan

1 Response

The oddly colored leaves look like a magnesium deficiency. You might try a spray of Epsom salts about a teaspoon in a gallon of water. Spray on the affected plants and then pour the rest on the soil around the plants.
The orange sporulation on the blackberries is orange rust. This disease infects blackberries and black raspberries but not red raspberries.
There is no cure and infected plants should be removed.
Here are some links to some MSUE articles.
These articles reference commercial fungicides for preventing the spread of the disease but the treatment window has passed.
There is a homeowner formulation of myclobutanil available. Look for Spectracide Immonox Multi-purpose Fungicide which can be used in the early spring to prevent infection. Examine the label closely as there are several formulation of Immunox available and you want the one that is only a myclobutanil fungicide and not a mix to insecticides and a different fungicide. I am not aware of other homeowner myclobutanil products but they may be out there.