A New Pest Concern in New England:
Chrysanthemum White Rust
with updated images
October 2007

Chrysanthemum white rust (Puccinia horiana) was confirmed for the first time in Connecticut on September 12, 2007 in Fairfield and Hartford Counties.  Infected plants were found in nurseries and garden centers during visual inspections by Connecticut Agricultural Experiment Station staff.  The disease was confirmed by Sharon Douglas from the Experiment Station and a USDA APHIS laboratory.  The plants that tested positive last week for chrysanthemum white rust (CWR) were ‘Gretchen’ cultivars.  Although CWR has occasionally been reported in the U.S. and Canada, all previous outbreaks were eradicated successfully.  CWR is a regulated pest of quarantine significance, and steps are being taken by state and federal regulators to remove and destroy infected plants from the two confirmed sites.  Additional inspections are underway at nurseries and garden centers in Connecticut. 

Chrysanthemum white rust infects 12 species of chrysanthemum, including garden mums, pot mums, and Nippon daisies.  The disease was first found in Japan and China more than 100 years ago, and has since become established in Europe, South America, Central America, Africa, Australia and parts of Asia.  Infected plants may not show any symptoms of the fungus during hot or dry conditions until the weather turns cool and wet.  Symptoms of CWR on infected plants include raised pink or white pustules on the underside of the leaf and chlorotic spots on the upper leaf surface.  Severe outbreaks of CWR may result in total crop loss. 

Additional information is available via the following links: 

USDA - APHIS - Plant Health, Plant Protection and Quarantine

USDA, ARS Systemic Botany and Mycology Laboratory

British Columbia Ministry of Agriculture Food and Fisheries


Chrysanthemum White Rust - pustules.  Sharon M. Douglas image

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Chrysanthemum White Rust - Plant damage.  Sharon M. Douglas image

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images from:
Sharon M. Douglas, Ph.D., Plant Pathologist Head,
Department of Plant Pathology & Ecology
The Connecticut Agricultural Experiment Station
123 Huntington Street (zip code 06511)
P. O. Box 1106New Haven, CT  06504  USA

Donna Ellis
Extension Educator and State Survey Coordinator,
USDA APHIS Cooperative Agricultural Pest Survey (CAPS) Program
University of Connecticut
Department of Plant Science
1390 Storrs Road, Unit 4163
Storrs, CT  06269-4163
Phone (860) 486-6448
FAX (860) 486-0534

email donna.ellis@uconn.edu

 UConn Integrated Pest Management: www.hort.uconn.edu/ipm/


Information on our site was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.

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