New National USDA Chrysanthemum White Rust (CWR) Eradication Protocol Released

This fall USDA, APHIS released a new Chrysanthemum White Rust (CWR) eradication protocol for nurseries containing plants infected with Puccinia horiana, the causal agent of CWR. The protocol can be found at http://www.aphis.usda.gov/ppq/ispm/cwr/cwrplan.pdf. This protocol provides a standard protocol for use by state and federal regulators to respond to new finds of CWR in nurseries in the U.S. This protocol was written to guide regulators in the successful containment and eradication of CWR, but it also provides information that may be of use to growers. The introduction provides background information on the pathogen including the history of CWR introductions in the U.S. and pathways for entry into the country. Appendix 1 “Management Practices for Growing CWR-free Chrysanthemums” lays out guidelines for excluding CWR from production areas, preventing CWR from establishing in nurseries and monitoring nursery stock for the disease. The remainder of the document serves to inform readers about what steps would be taken to insure successful eradication of CWR in an infested facility and the surrounding environment.

While chrysanthemum white rust is not established in the United States, it has been periodically found in the U.S. and subsequently eradicated. In 2004 CWR was reported in one location in Norfolk County, Massachusetts. The Massachusetts Department of Agricultural Resources worked with the grower to eliminate the disease from their facilities and surveyed the surrounding area to insure the rust had not spread. Early detection and reporting of potential CWR infections are critical to ensure that spread is contained and eradicated. In 2005 nurseries and retail outlets in Massachusetts were surveyed for CWR and found to be free of the disease.

This pest alert is from the Massachusetts Introduced Pests Outreach Project, a collaborative project between the Massachusetts Department of Agricultural Resources and the UMass Extension Agriculture and Landscape Program aimed at preventing the establishment of new pathogens and pests in Massachusetts. Visit the project website (http://www.massnrc.org/pests) for more information on chrysanthemum white rust or other emerging pests and to subscribe or unsubscribe from our pest alert list.