Knowledgebase

Blackberry Rust Spot? #230070

Asked March 08, 2015, 10:50 PM EDT

Hi! I noticed that my trellised trailing blackberries (I think they're marionberries) developed a fungus over the winter (see the attached photos of a front and backside of a leaf). I pinched off all of the affected leaves (which was 90% of them) and I was thinking of applying an organic or non-toxic fungicide. Do you think this is a good idea, and if so what would you recommend - copper sulfate? Neem Oil? Thanks so much for your help! Mike Christopher

Washington County Oregon

Expert Response

Glad you included both sides of the leaf as this is a rust fungus. I suspect it is the common rust and not anything exotic. Many growers have been seeing these symptoms this year. Removing leaves is fine. You can try a copper-based fungicide to protect the new leaves as they come out this spring. See what they might have available at your local nursery or supply store. More information can be found here:
http://pnwhandbooks.org/plantdisease/blackberry-rubus-spp-cane-and-leaf-rust

Jay W. Pscheidt, PhD, Professor Replied March 09, 2015, 6:24 PM EDT

Loading ...