Cause There are 8 different species of Puccinia reported from the PNW on Carex sedges. Sedges are the telial host while the alternate host is variable and dependent on the rust species. Uromyces perigynius is another rust reported from Oregon and Washington.
Symptoms Uromyces perigynius - The floral structures known as perigynia become dark colored before maturing. The pustules form globular patches on the outside and between the veins. Young leaves develop pustules on both sides that are generally 3 times longer than they are wide.
Puccinia - looks like long black rows on the leaves.
Cultural control
- Grow resistant cultivars.
- Destroy affected leaves or plants if practical.
- Avoid overhead irrigation or apply such that plants are not wet for extended periods of time.
Chemical control Many different fungicides are labeled for this disease but do not have Carex or sedges on the label but may legally be used. Test first on a small section before applying on the whole plant to evaluate possible phytotoxicity.
References Halsted, B. D. 1889. An interesting Uromyces. The Journal of Mycology 5:11.