Cause Melampsoridium alni and M. hiratsukanum are present in Curry County, Oregon. M. hiratsukanum has been reported in British Columbia. An unidentified, and sparsely occurring, rust was observed on leaves along the Mckenzie River in Oregon. It is not a very common or obvious problem around the region.
Symptoms Small yellow pustules (uredinia) occur on leaves in summer. Leaves later turn dark brown (telia). Alternate host is suspected to be a conifer.
Cultural control No cultural controls are listed.
Chemical control
- Eagle 20 EW at 6 to 12 fl oz/100 gal water. Group 3 fungicide. 24-hr reentry.
- Myclobutanil 20 EW T&O at 6 to 12 fl oz/100 gal water plus spreading agent. May observe a PGR effect. Group 3 fungicide. 24-hr reentry.
Reference Hantula, J., Nigel Stringer, R., Lilja, A. and Kurkela, T. 2012. Alder rust, Melampsoridium hiratsukanum Ito, identified from Wales, UK and British Columbia, Canada. Forest Pathology, 42:348-350.