CWR Adds Another State to the List

November 5, 2004 - 11:31

Early last week USDA confirmed the presence of Chrysanthemum White Rust (CWR) in nurseries and some residences in Pennsylvania, Delaware, Maryland and New York, according to the USDA’s Phytosanitary Alert System.

The Pennsylvania Department of Agriculture (PDA) collected and diagnosed a positive sample on Sept. 17, 2004, from a nursery operation in Chester County, Penn., and the USDA confirmed that diagnosis on Sept. 22, 2004. Approximately 4,000 plants have been destroyed at the positive Pennsylvania nursery according to the USDA.

“Upon the determination of the positive diagnosis, PDA provided the Delaware Department of Agriculture (DDA) trace forward information,” the Alert stated. “DDA then submitted 22 suspect specimens to USDA for identification; all confirmed positive for CWR on Sept. 24, 2004. Five retail nurseries and four private properties in New Castle County, Del., were determined to have infected mums.”

The next outbreak confirmations came on Sept. 24, 2004 when the Maryland Department of Agriculture received a suspect CWR infected sample collected at a nursery located in Montgomery County. The sample was confirmed positive by USDA on Sept. 29, 2004. Approximately 1,000 field-grown chrysanthemum plants of several varieties have been destroyed at the Maryland nursery, according to the Alert.

The most recent reported case came in on Sept. 27, 2004 from the New York State Department of Agriculture and Markets when it detected suspect CWR infected samples from two garden centers in Westchester County. The samples were confirmed on October 5 by USDA and on October 12 by Cornell University at the Long Island Horticultural and Extension Center, which is in the National Plant Diagnostic Network. A total of 771 chrysanthemum plants have been destroyed from both infected garden centers, according to the Alert.

At this time, there have been no connections established between the positive CWR finds in the four states, but currently, trace back and trace forward investigations are in progress, and the National CWR Management Plan for Exclusion and Eradication is being implemented.

“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,” the Alert stated.

“When CWR is found in the United States, the states and PPQ cooperate to eradicate it. CWR is established in Europe, Africa, Australia, Central America and South America. 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.” To learn more about the details on the Federal regulatory program, contact Staff Officer Ved Malik at (301) 734-6774.

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