Chrysanthemum White Rust (CWR), Puccinia horiana P. Henn., has been confirmed in one Pennsylvania nursery on September 17, 2004. As a result of trace forwards from that nursery, CWR has also been confirmed in one Delaware nursery.
A suspect CWR sample was collected and diagnosed positive on September 17 by the Pennsylvania Department of Agriculture (PDA) from a nursery operation in Chester County, Pennsylvania. This diagnosis was confirmed by United States Department of Agriculture (USDA) on September 22, 2004. Approximately 800 field grown chrysanthemum plants of several varieties exhibited symptoms at the positive Pennsylvania nursery. Upon the determination of the positive diagnosis, PDA provided the Delaware Department of Agriculture (DDA) trace forward information. DDA then sampled and submitted 22 suspect specimens to USDA for identification which were all confirmed positive for CWR on September 24, 2004. PDA and DDA are following the National CWR Management Plan for Exclusion and Eradication.
CWR, caused by the fungus Puccinia horiana P. Henn., is a quarantine pest for the United States. The importation of CWR host plants is prohibited from infested countries and regions due to the potential of this organism to be transported with the host plants. When CWR is found in the United States, the States and PPQ cooperate to eradicate it. CWR originated in eastern Asia. It is now established in Europe, Africa, Australia, Central America, and South America. There have been past outbreaks in the
United States, but the pest was eradicated in each instance. Disposal of infected plants and weekly fungicide sprays of myclobutanil are required to manage this disease as outlined in the CWR Management Plan for Exclusion and Eradication. If you wish more details on the Federal regulatory program, you may contact Staff Officer, Dr. Ved Malik at (301) 734-6774.