USDA lifts quarantine on mum disease, sees little risk to Alaska's wild chrysanthemum

The U.S. Department of Agriculture is lifting its quarantine on a fungal disease that attacks chrysanthemums, the flowers often sold as mums, and will let chrysanthemum cuttings from 20 countries into the continental United States starting Nov. 9.

The agency says the change will not significantly affect the only chrysanthemum native to the United States, a coastal Alaska wildflower known as the Arctic daisy. It grows on beaches near the tideline, in salt marshes and on coastal tundra, according to the Flora of North America.

The Alaska plant came up because someone who commented on the proposal argued that the disease, called chrysanthemum white rust, should stay regulated to protect native chrysanthemums. Older federal import rules had listed the plant, Chrysanthemum arcticum, as a host of the disease. The agency answered that the plant's limited distribution in northern coastal Alaska, and the climate there, mean it will not be significantly affected. A 2022 study describes a wider range: populations on Alaska's southwest and western coasts and in the Aleutian Islands, and along much of Canada's coastline.

The agency said trying to wipe out the disease is no longer technically or economically justified. The fungus can spread through a plant without showing symptoms and survive winters in roots and other underground parts, it is likely already established in the country, and fungicides let growers manage it at a fraction of a plant's value.

The 20 countries include Colombia, Mexico, the Netherlands and Kenya. Under the agency's plan, each would sign a written agreement with it setting conditions for growing and monitoring the plants. Imports from Canada are covered under a separate protocol. The department's Animal and Plant Health Inspection Service announced the decision in an Oct. 7 program update and published it in the Federal Register on Oct. 8.