Cane and Leaf Rust of Brambles
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Cane and leaf rust (Kuehneola uredinis) is a fungal disease of blackberry. Raspberry infections are rare. Symptoms resemble orange rust, but unlike orange rust, cane and leaf rust is not systemic; instead, infections are restricted to plant surfaces. Symptoms begin in mid-April and extend through summer. In spring, floricanes split and release yellow spores. These spores infect floricane leaves, and yellow pustules persist on undersides of leaves from harvest through autumn, infecting other leaves throughout the growing season when conditions are rainy. Defoliation can occur if infections are severe. A different spore type can infect primocanes and leaves. Overwintering occurs in infected canes.
Cane and leaf rust on blackberry cane (note orange-colored rust pustules).
(Photo: Yesica Cisneros)
Close-up of pustules on a cane.
(Photo: Elizabeth Bush, Virginia Tech., Bugwood.org)
Rust pustules on lower (left), and upper (right) leaf surfaces.
(Photo: OSU Plant Clinic, Oregon State University)
Rust pustules on fruit.
(Photo: OSU Plant Clinic, Oregon State University)
Management:
- Practice proper sanitation (remove floricanes after harvest; remove all diseased canes; destroy prunings or discard away from plantings).
- Increase air circulation to encourage drying of plant tissues (pruning, thinning, spacing, and managing weeds).
- Apply fungicides to protect healthy plants.
