Latin names: Arthuriomyces peckianus

Common name: Orange Rust

Plant family: Brambles

Date/Location of specimen: On wild blackberries on property May 2011

Description: Orange rust is a fungal disease that occurs only on brambles, particularly blackberries, dewberries, and black raspberries. This is a systemic disease. Once the plant is infected, the entire plant is infected for life … When the orange spore pustules mature and break open in June or July, the spores are spread to other plants by the wind. The fungus enters the plant through the leaves and grows internally through the canes, crowns, and roots. Newly infected plants seldom show symptoms until the following spring.1
Orange rust does not normally kill plants, but causes them to be so stunted and
weakened that they produce little or no fruit.2
Arthuriomyces peckianus occurs primarily in the northeastern quarter of the United States and is the causal agent for the disease in Ohio.

Control: No chemical control is known for this disease. Some blackberries, specifically Ebony King, Eldorado, and Raven, are reported to exhibit resistance.1 When diseased plants first appear in early spring, dig them out (including roots) and destroy them before
pustules form, break open, and discharge the orange masses of spores. If plants are not removed, these spores will spread the disease to healthy plants.2

References:
1 http://extension.psu.edu/plants/gardening/fphg/brambles/diseases/rust
2 http://ohioline.osu.edu/hyg-fact/3000/pdf/HYG_3010_08.pdf

Collection Sample #5 of 5 DISEASES

Master Gardener Class Horticulture Portfolio