Greenhouse Canada

Grower alert: Chrysanthemum White Rust

July 2, 2008  By Ohio Floriculture Association

July 2, 2008 – The OFA, the Society of American Florists and the American Nursery & Landscape Association are warning growers that it's never too early to begin thinking about the fall chysanthemum crop. The associations are joining together to design a free 'webinar' on chysanthemum white rust.

The OFA, Society of American
Florists and American Nursery & Landscape Association are warning
growers that it's never too early to begin thinking about the fall
chysanthemum crop. In fact, now, as you are getting your new cuttings started, is the perfect time to focus on protecting yourself, and helping protect the North American industry, against Chrysanthemum White Rust (CWR).
This disease has occurred in a limited number of growing operations in the Northeast, the Pacific Northwest, California, and Canada over the past few years, causing economic harm to those few growers who were impacted.
Because it is considered a quarantine significant pest by both the United States and Canada, it is particularly important for all growers to be aware of steps they can take to avoid having the disease in their mum crops. Federal and state governments are working with the major propagation and breeding companies to try to better understand and prevent these kinds of outbreaks – but participation of commercial growers in that effort is essential. You need to be aware of this quarantine disease and how to prevent it.
Exclusion and prevention are the first lines of defense.
Since CWR has never been traced back to reputable cutting producers, make sure you are buying your cuttings only from a reputable commercial source.
Never allow imported flowers or bouquet production in mum-growing greenhouses or headhouses. If you do allow imported flowers on your premises during mum-growing season, you must maintain strict separation from your production facilities, and must be sure that workers are not moving between the two areas and potentially carrying the disease on their hands, clothing, or equipment.
Scout your crops often. Maintain low humidity and dry foliage. Maintain clean growing practices.
Early detection and eradication are the second lines of defense.

If you do see this disease, because it is a quarantine-significant pest, you will need to inform your USDA, state, or county officials who will supervise the eradication and treatment process. Nonetheless, early detection and eradication will be much less costly for you than an unanticipated detection during the fall shipping season!
SAF and ANLA have joined together to design a free training session on CWR. The session is a "webinar" (a seminar conducted entirely online, from your computer). The seminar is approximately 30 minutes, has excellent photographs of CWR symptoms, and offers important advice on how to avoid it in your 2008 chrysanthemum crop.
The Webinar is available on SAF's website, on the top right hand corner under Grower Alert, and on ANLA's website,


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