State and federal agriculture officials are battling a fungal disease that can severely damage most types of chrysanthemums.
A nursery owner contacted the Michigan Department of Agriculture on Aug. 5 after noticing mums obtained from outside the state apparently were infected with chrysanthemum white rust. The MDA and U.S. Department of Agriculture have been working with the owner to properly dispose of the plants and oversee sanitization of equipment that came in contact with the affected mums.
Chrysanthemum white rust, a disease native to eastern Asia, may be recognized by small white to yellow spots, up to four millimeters wide, on the upper surface of the leaf. Pustules form on the underside of the leaf beneath the small spots, which become brown over time.