In the past few years, chrysanthemum white rust has caused economic harm to growing operations in Northeastern states, the Pacific Northwest, California and Canada. All growers should be aware of steps they can take to protect their mums, especially because the United States and Canada consider the disease a quarantine-significant pest. Though federal and state governments are already working with major propagation and breeding companies to better understand and prevent outbreaks, commercial growers' participation is essential for success in these efforts.
To prevent CWR, buy your cuttings from reputable commercial sources, and don't allow imported flowers or bouquet production in mum-growing greenhouses. If you do, enforce strict separation of production facilities and make sure workers aren't moving between the two areas and potentially carrying the disease on their clothes or equipment. Scout your crops often, maintain low humidity and dry foliage, and practice clean growing.
If you do detect the disease in your crops, inform your USDA, state or county officials, who will supervise the eradication and treatment process.
View a free training webinar at www.safnow.org  or www.anla.org . This 30-minute presentation will teach you how to recognize and avoid CWR in your 2009 mum crop.
For more information on chrysanthemum white rust and its treatment and prevention, look for Syngenta Flowers' Jane Trolinger's article in the September issue of GPN.