Seed & Chemical
Committed to IRM compliance
Bt corn growers protect technology for future use.
November 13, 2007 By Top Crop Manager
Eastern Ontario corn producer, Dave Bryan is committed to protecting the technology
that has protected his crop from European corn borer (ECB) damage for almost
10 years. "I feel I can't afford not to. If we get to the situation where
we have resistance, it's going to get very expensive. I have to protect that
technology for the future," says Bryan who has been growing Bt corn since
its Canadian launch more than a decade ago. With several growing seasons of
Bt use under his belt, Bryan is convinced of its value and does not want to
risk losing its benefits. "It stands better, stays greener longer than
non-Bt, and subsequently yields better."
Fellow growers are continually discovering the advantages of Bt, too. According
to a recent study, the percentage of acres planted to ECB technology continues
to grow; it is up by 2.4 percent from 2003 and 10.4 percent from 2001. But an
increase in acres also means an increased commitment is required to protect
the technology for future use.
"I certainly hope that everyone is following the rules," says Bryan
who planted nearly half of his North Dundas farm to corn in 2005. "The
rules are there to benefit all of us – to protect the technology."
The rules Bryan is referring to are the insect resistance management (IRM)
principles every grower who plants Bt corn must adhere to. Planting a 20 percent
refuge of non-Bt corn within a quarter mile of Bt hybrids is at the top of the
list. Matching the maturity of the non-Bt hybrid with the Bt hybrid (within
100 to 150CHU) is key, as is scouting for ECB damage and keeping good records.
Finally, use of an ECB insecticide on the non-Bt crop is not permitted.
These resistance management practices help encourage the movement of adult
corn borers between Bt and non-Bt hybrids for genetic mixing to ensure that
resistance does not develop.
Study shows high level of compliance
A biennial study carried out by the Canadian Corn Pest Coalition (CCPC) in Ontario,
Quebec and Manitoba, shows that grower compliance with the principles is still
high. CCPC, made up of government, university and industry stakeholders, found
that during the 2005 growing season, 80.3 percent of growers using Bt technology
complied with the 20 percent refuge requirement. This marks a small decline
from the 2003 survey. When it comes to the refuge distance requirements, nearly
90 percent of growers complied, a slight increase over the previous survey.
The results are impressive, but what is keeping Canadian growers from scoring
perfect marks? Ironically, one of the factors could be the proven performance
of the technology – some growers are not willing to put any of their crop
at risk of ECB damage by being without it. "You can't predict an ECB infestation.
It can be severe in any given area in any given year," says Gary Bauman,
head of technology and agronomic services for NK Brand Seeds. "We have
documented value of more than eight bushels per acre return when managing the
pest by planting Bt-protected corn."
Combine the pests' unpredictability with the probability of getting an eight
bushel per acre yield advantage and it is no wonder that some growers are tempted
to plant their entire crop with Bt hybrids. Growers like Bryan, however, know
that in order to take advantage of the technology in the long-term they need
to use it responsibly in the short-term.
Putting principles into practice
Bryan's planting system makes it easy for him to comply with the principle of
keeping a 20 percent non-Bt refuge in close proximity to his Bt crop.
"We have a 16 row planter. We fill three or four hoppers with non-Bt corn
and the remainder with the Bt hybrid. This way we're assured a 20 to 25 percent
refuge and there is no chance of getting Bt and non-Bt seed mixed up."
According to Bauman, mixing the two can be an issue on some farms. "There
seems to be a practice with some growers for unintentional mixing because they
are not cleaning out their planters between Bt and non-Bt passes. A mixture
encourages resistance development," he warns.
Bryan's system has removed any chance of this happening with his planter. "I
don't see anything complicated about it at all. You can easily calculate the
20 percent refuge with our set-up. Guys with four row planters can't do it like
us, but they can plant their non-Bt on the headlands. Another way to ensure
that we have enough refuge is that when we buy our Bt corn from NK Brand, we
buy the required amount of refuge right off the bat," says Bryan.
While seed companies cannot insist that a grower purchase their non-Bt seed
at the time that they purchase their Bt hybrids, they do have an important role
to play in educating and monitoring stewardship compliance.
"We make a significant effort to support the technology," says Bauman.
This includes a NK Brand ECB scouting program with dealers and representatives
to monitor presence and damage in customer fields. "We conduct a phone
survey every year to review what they think of Bt corn and the stewardship principles.
In many cases, we go onto the farm, discuss the principles and answer any objections
A challenge some growers pose is the yield penalty that can be associated with
the non-Bt refuge. "We typically try to help them find the best genetics
for their fields or help them manage their planting schedule. Studies done at
NK Brand with growers have shown that the first planted or last planted shouldn't
be their refuge," says Bauman. "These things help to reduce some of
the headache and minimize broken stalks."
Room for improvement
While Canadian corn producers have consistently scored an 'A' on the refuge
requirements of the biennial compliance report card, there is still room for
improvement with other principles. "The study showed that 63.4 percent
of growers are keeping records and 30.6 percent are scouting crops for resistance.
These are areas that require continued improvement by growers and the industry,"
"We keep records of where everything is planted. In fact, we keep records
of everything we do daily," says Bryan, who understands it is fundamental
to know where and when he planted to be able to monitor for ECB. "We start
scouting in late August. We have yet to see any evidence of ECB in our Bt corn."
It is thanks to growers like Bryan and others who comply with the stewardship
principles that no case of resistance has been confirmed. But what will happen
in the event resistance becomes reality?
"A remediation program was recently set up by CCPC in case true resistance
is ever confirmed," says Bauman. "The resistant field will be quarantined
and additional monitoring of nearby fields will occur in an effort to contain
Bauman remains positive that the remediation program will never have to be
enacted. "The stewardship principles work and the technology is very sound.
It performs and produces value for growers. Bt has been one of the most valuable
tools for the corn industry in the last 10 years because of the yield that has
been protected. We have not seen any indication of resistance and I hope we
have at least another 20 years with the technology." -30-