Top Crop Manager

Features Agronomy Diseases
Fungicide’s arrival and performance welcome

Research backs industry expectations.


November 13, 2007
By Top Crop Manager

Topics

16aJune, fusarium head blight and fungicides. The three come together in a way
that tends to create a significant degree of anxiety in growers each year. In
the words of one researcher, 'the industry takes and holds a collective breath
in anticipation of the critical time for infection'. In 2006, early forecasts
for fusarium and its resulting levels of deoxynivalenol (DON) toxins gave rise
to taking that breath, as prognostication models moved quickly from green to
yellow, denoting a potentially hazardous shift. However, a hot and relatively
dry spell through much of June defused most concerns of a widespread fusarium
outbreak.

To help in the ongoing struggle with the disease, growers have had access to
Proline (prothioconazole), a sterol biosynthesis inhibitor, which makes it a
Group 3 fungicide. Newly registered for 2007, it boasts a protective, curative
and eradicative activity and its efficacy is considerably higher, according
to independent research from the University of Guelph.

Dr. David Hooker, who led the research work at the university's Ridgetown Campus,
conducted more than 500 comparisons measuring various parameters, including
average grain yield, optimum timing and application rates. The data were gathered
during a three year period starting in 2003 and continuing in 2004 and 2006.
Hooker measured the responses in different varieties and across different locations
in the first two years.

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In most fields and years, the application of Folicur and Proline increased
grain yields by at least 4.5 percent. Furthermore, there was little difference
between Folicur and Proline in yield response in low to moderate fusarium infection,
even though Proline produced numerically higher yields. For example, in 2003,
Folicur and Proline increased average yields by 4.5 percent versus 4.9 percent,
respectively, in 116 comparisons. In 2004, doing the same variety and location
comparisons, Folicur managed a 4.6 percent increase with Proline holding an
8.8 percent yield advantage across 136 comparisons.

In 2006, with 260 comparisons, Folicur managed a 3.8 percent increase while
Proline boosted yield by 6.5 percent. The responses in yield are not without
some variability. "The response across varieties and year actually ranged
from a zero percent yield increase on some varieties with others showing up
to 18 percent yield bump after a fungicide application, which is tremendous,"
says Hooker. "We didn't have enough trials out there to say what variety
is better than another."

In terms of reducing fusarium damaged kernels (FDK) and DON levels, Proline
consistently out-performed Folicur, with a general reduction of DON of about
65 percent, but with a range of 30 to 72 percent. That compared to Folicur's
10 to 45 percent reduction. As for early and late applications, Hooker's research
indicates that too early applications where the wheat heads were not emerged
meant no coverage, so no impact on fusarium and DON levels. With too late applications
(i.e. six to seven days after head emergence), there is the risk of reduced
control in general, but better timing and subsequent control on late tillers.

The fight against the disease is increasing
The good news from Hooker's perspective is the severity of the province wide
outbreak in 1996 actually spurred the effort in research into fusarium. "A
decade ago, little was known about DON and now a lot more is known that really
raises a lot of flags with health concerns and that's been gaining worldwide
attention," he says.

He adds that much more has been done through research to develop more tolerant
varieties to determine the impact of spray/no spray decisions, to learn more
about the disease and its effects, and on handling and marketing of infected
or contaminated grain. "As all of these gain more attention, more emphasis
is placed on research to manage the disease and reduce toxins."

For Luc Bourgeois, Proline's arrival may be viewed as long overdue even though
its registration only occurred in 2006. Bourgeois, lead researcher for Bayer
CropScience, began working with the fungicide in 1998 and the product has had
extensive use across Europe. "I've seen the product for a long time, and
it convinced me of its impact by the fall of 1998," he says, adding he
is confident it will become popular with growers as they begin to use it. "It
quickly convinced people like Dr. Art Schaafsma from the University of Guelph,
and it convinced the researchers that are part of the scab initiative in the
US and Canada."

Proline's registration is as significant to western Canadian canola growers
as it is to eastern Canada wheat growers. It will also benefit those with barley
and pulses. "On fusarium, it's definitely a step above," says Bourgeois.
"In terms of septoria, it also has a slight advantage, but where Folicur
still shines above the competition is on the rusts."

The best news for growers regarding fungicides is unlike herbicides, the research
and development pipeline is active. Bourgeois notes there is more work on newer
chemistries, with better products yet to come. "We are hoping in the near
future to have a better segmentation as well, to basically have a canola product
and a wheat product," he says.