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Disease Prevention Tools for Greenhouse Growers

The Tomato Magazine
August 2006

A recent outbreak of bacterial canker in British Columbia, Canada, left greenhouse growers looking for answers. While unable to provide a cure, Seminis responded to this outbreak by sending Dr. Kevin Conn, a senior scientist from Seminis’ plant pathology lab in Woodland, Calif., to visit with growers and provide them with more information about bacterial canker, its epidemiology and control measures.

“Bacterial canker is the kiss of death to a seed lot,” Conn said. “Our varieties were not suspect, but we wanted to offer support, now and later on, to the growers. We’re concerned; we want growers to be successful.”

Along with Seminis sales manager Joep van de Burgt, Conn visited four greenhouses in the Delta area, some of which had recent problems with the disease and others looking for more information about prevention.

Conn visited with grower Gert Van Straalen at Millennium Pacific Greenhouse Partnership. While the producers had not encountered problems with bacterial canker in their greenhouses, they were pleased to have more information about the disease.

“It was an extremely useful visit,” Straalen said. “Kevin’s brain is full of information. He showed me some things about bacterial canker that I had never seen before. He made us more aware of the problem and was very helpful.”

A real concern for growers, bacterial canker, caused by Clavibacter michiganensis subsp. Michiganensis, can survive for up to three or more years in infected plant debris. It can also survive on weeds, volunteer tomato plants and seed. This disease can be spread by splashing water and the use of contaminated equipment and tools in pruning, clipping and transplanting operations. Moderate temperatures and greater than 80 percent relative humidity favor disease development.

Conn recommended many control measures including, but not limited to, the following:

• Only use seed from certified seed lots that have been assayed for the presence of bacterial canker.
• Wash hands and arms thoroughly with soap and water before working with plants.
• Workers should wear freshly laundered clothing each day.
• Remove all plant debris.
• Check plants frequently. Suspect and infected plants should be removed and burned.

“There’s no silver bullet, no real answer in this outbreak,” Conn said. “The growers here run such clean operations that it’s hard to imagine where the bacterium are hiding. I’m very impressed; these are the most sophisticated growers I’ve met.”

For more information about bacterial canker or to request a copy of Seminis’ Tomato Disease Guide, contact your local Seminis representative.

© 2006 Columbia Publishing

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