Chrysanthemum White Rust to Lose Quarantine Status
The USDA will shift to a systems-based management approach for the fungal disease starting on December 9, 2026.
Updated on Oct. 20, 2026 in Botany
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Effective December 9, 2026, the USDA will remove chrysanthemum white rust from its status as a quarantine pest in the United States. This regulatory change follows an economic assessment concluding that an eradication-based strategy for the fungal disease is no longer justified.
Why it matters
The decision marks a shift from total eradication to containment, acknowledging that the pathogen is already established within U.S. borders. This allows the agency to streamline import protocols for chrysanthemum products while shifting the burden of management to existing industry-standard fungicide practices.
The APHIS policy transition impacts import requirements across 20 countries, replacing quarantine-based eradication with a systems approach. The protocol relies on existing industry-standard fungicides to manage Puccinia horiana, the fungus responsible for white rust, in place of previous entry prohibitions.
The players
APHIS
The Animal and Plant Health Inspection Service, a USDA agency tasked with protecting U.S. agriculture from pests and diseases through regulatory oversight.
The details
Chrysanthemum white rust is a fungal disease caused by Puccinia horiana that manifests as pustules on the undersides of leaves. Because the pathogen is now considered established in the U.S., APHIS is moving to a systems approach—a series of integrated measures for pest risk management—rather than exclusion. Growers will continue to use approved fungicides and standard horticultural practices to manage the disease within their operations.
Timeline
November 9, 2026: Official publication of regulatory changes.
December 9, 2026: Regulatory changes become effective 30 days after notice.
The Tech Race
This policy change updates the regulatory framework established under 7 CFR 319 Subpart P-Cut Flowers to reflect the reality of established pathogen populations. It aligns domestic standards with the current operational necessity of managing, rather than excluding, Puccinia horiana.
Beginning December 9, 2026, importers will follow consolidated requirements for chrysanthemum species and cut flowers from 20 nations. The change simplifies the administrative process for florists and nurseries currently navigating quarantine-era documentation.
The takeaway
The move recognizes the endemic status of the fungus and pivots to industry-led management. Stakeholders should monitor updated protocols in the Agricultural Commodity Import Requirements database for specific shipment guidelines.
Further reading
For more on plant health and regulatory shifts, visit the Botany section.
More information
For official documentation on the rule change, visit the regulations.gov search for regulatory details.
Source note: This article includes information reported by Greenhouse Management.
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