Canada
March 11, 2009
Preliminary results from a cross-Canada potato leaf sampling
program show widespread presence of a mutation in the fungus
Alternaria solani, the cause of potato early blight. More than
80% of the 113 isolates collected tested positive for F129L, a
mutation that results in reduced sensitivity to strobilurins.
The results confirm what many experts expected – the reduced
sensitivity of strobilurins to early blight is a widespread
issue affecting many potato-growing areas of Canada. Reduced
sensitivity doesn’t mean strobilurins don’t work at all, they
just don’t work as well as they have in the past for controlling
early blight.
Early blight leaf tissue samples were collected during the
summer of 2008 in Alberta, Manitoba, Ontario and Prince Edward
Island through collaborative efforts of
Bayer CropScience
sales representatives and provincial potato specialists.
“Initial results confirm that mutant strains are widespread in
Alberta, Manitoba and Ontario, which is not surprising given the
widespread distribution of mutant strains of the early blight
fungus in the United States,” says Dr. Rick Peters, research
scientist with Agriculture and Agri-Food Canada in
Charlottetown, PEI who is overseeing the testing of the recent
samples. “To date, PEI is the only area that we’ve surveyed
where all samples were still sensitive to strobilurins, likely
due to the less frequent use of strobilurins in this province.”
The message to potato growers is clear, based on the results of
this recent sampling program. “Develop a sound fungicide
management plan to rotate product groups,” says Andrew Dornan,
Field Development Representative, Horticulture with Bayer
CropScience. “Strobilurins are very susceptible to resistance,
and we can’t reverse the effects of the level of reduced
sensitivity we are seeing with early blight, and growers need
new effective options for early blight control.”
“We’re putting our heads in the sand if we ignore this growing
issue with reduced sensitivity to strobilurins,” says Manitoba
potato pest specialist Dr. Tracy Shinners-Carnelley. “When the
risk for early blight is high, look at the tools available and
use them appropriately in a planned program. And if strobilurins
are part of that program, they must be tank mixed with a
protectant fungicide.”
With the widespread presence of early blight with reduced
sensitivity to strobilurins, potato growers need new options for
early blight control. Scala® fungicide can play an important
role as the only Group 9 fungicide registered for control of
early blight in Canada, with a mode of action that is unique and
different from strobilurins. And Scala is registered as a tank
mix with Bravo®, providing two modes of action for stronger
resistance management.
Bayer is a global enterprise
with core competencies in the fields of health care, nutrition
and high-tech materials. Bayer CropScience AG, a subsidiary of
Bayer AG with annual sales of about EUR 5.8 billion (2007), is
one of the world's leading innovative crop science companies in
the areas of crop protection, non-agricultural pest control,
seeds and plant biotechnology. The company offers an outstanding
range of products and extensive service backup for modern,
sustainable agriculture and for non-agricultural applications.
Bayer Crop¬Science has a global workforce of about 17,800 and is
represented in more than 120 countries. Further information on
Bayer CropScience Canada is available at:
www.bayercropscience.ca
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