|Orange Cane Blotch. Picture Gina Fernandez.|
I first saw this about 10 years ago in southeastern NC, before the blackberry industry expanded through the state. The site was in the extreme southeastern part of the state. Without the benefit of a digital image, I had assumed it was the more common disease orange rust. However, when I saw the the plants, the symptoms were not what I was expecting. We finally determined it was Orange Cane Blotch.
This disease is now in many counties in NC. I see it most often in plantings with high plant density, lots of vegetation in alleys (weeds or cover crops) and when beds are not raised or do not have plastic. A simple way to tell the difference between orange cane blotch and orange rust is to lightly rub the infection site. When the orange felt colonies are rubbed, they cause a stain, but a light rubbing of an orange felt colony does not cause a stain on your fingers.
Dr. Phil Brannen prepared a circular on this disease, including suggestions for biological and chemical controls. Here is a link: