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NEWS RELEASES - 2007
Canker Sores Cost Millions
(Guelph, ON – April 30, 2007) Bacterial canker is a very contagious disease in
tomatoes that the Ontario Greenhouse Vegetable Growers (OGVG) is hoping to
control or even eliminate through the promising results of a two-year research
project.
The disease is a significant problem in Ontario’s $210 million greenhouse tomato
industry as one infected seed can kill a grower’s entire crop. The bacteria are
currently controlled through the use of disease-free plants, hygiene and crop
rotation. However, these measures cannot control the disease once started. With
over 800 acres of greenhouse tomatoes being grown every year in the province,
it’s a problem worth addressing.
Over the past two years, the OGVG has undertaken a research project designed to
better understand how the disease spreads, determine how long spores live, how
they travel, optimum growing conditions, preference/life span on different plant
materials in different temperatures, and new methods by which farmers can
control or even eliminate the disease. Caused by the Clavibacter michiganense
bacteria, the disease causes the leaves on the plant to discolour, wilt and even
drop off, halting its ability to photosynthesize sunlight. In other words, the
defoliated plant can’t feed itself and dies.
Under the leadership of the now retired Dr. J.C. Tu, at Agriculture and Agri-Food
Canada’s Greenhouse and Processing Crops Research Centre in Harrow, Ontario, a
team of researchers monitored tomato plants at all stages of growth for the
presence of the canker bacteria. Data was recorded on the incidence and severity
of the disease, when the disease was first spotted, how it spread, and how it
was managed. Tools, benches, troughs, soil, compost, plant debris and even the
actual building materials of greenhouses were tested to determine how long the
bacteria could survive on each material. As well, various disinfectants were
tested for their ability to kill the bacteria.
After a year of work, the results are in. It was discovered that the bacteria
could survive on all of the tools and surfaces in and around the greenhouse. On
plant debris however, bacteria could survive for more than six months and
remained highly infective. Spores also seemed to stick better to plastic and
survived longer in warmer temperatures. It was also noted the severity of the
disease was directly related to the concentration of the bacteria, and when
inoculated with the bacteria, younger plants died quicker than larger, more
mature ones.
In regards to disinfection, it was found that two compounds were effective on
controlling the bacteria on tools and surfaces, but less so on plant debris.
What does this mean for the industry? Unfortunately disinfecting tools is not
very practical on a production scale. Even if it only takes two seconds to dip a
tool into disinfectant, when multiplied by thousands, it’s too long.
One of the more promising results lies with the use of a micro-filtration
system. Greenhouse tomatoes are grown in a hydroponic or soil-less environment.
Fertilizer is added to the water, providing the plant with all the nutrients
necessary for it to grow and produce. For both environmental and financial
reasons, this nutrient solution is recycled and reused. It was discovered that
the canker bacteria was also being recycled, allowing the disease to easily
spread from contaminated to healthy plants. Researchers discovered that the use
of additional filters in the recycling system were able to trap and therefore
halt the spread of the bacteria. These micro-filters are now being tested on
more greenhouses to verify these positive results.
This project is funded in part through contributions by Canada and the Province
of Ontario under the Canada-Ontario Research and Development (CORD) Program, an
initiative of the federal-provincial-territorial Agricultural Policy Framework
designed to position Canada’s agri-food sector as a world leader. The
Agricultural Adaptation Council administers the CORD Program on behalf of the
province.
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For more information:
Nadine Armstrong
Communications Manager
Agricultural Adaptation Council
Ph: 519-822-7554
E-mail: narmstrong@adaptcouncil.org
Website: www.adaptcouncil.org
