GrainsWest Winter 2017

35 / 44

Winter 2017 35
Fighting Fusarium
The Alberta Fusarium graminearum Management Plan offers
several recommendations for combating F. graminearum:
• Always use healthy seed with no detectable levels of
F. graminearum to avoid introducing the pathogen into
your production area.
• Prior to planting, treat all cereal and corn intended for
use as seed in Alberta with a registered fungicide that
includes the genus Fusarium on the label list of fungi that
are controlled.
• Leave at least two years between host crops (e.g., all small
grain cereals, corn). Continuous or short-rotation cereals
or corn allow for a buildup of F. graminearum on infested
residues.
• Avoid corn in rotation with small grain cereals. Corn is
also a host of F. graminearum, where it causes seed rot,
seedling blight, root rot, stalk rot and ear rot. However,
ultra-susceptible classes of wheat like durum or individual
varieties can also greatly increase the risk of infested
residues.
• If practical, avoid planting small grain cereals immediately
adjacent to cereal or corn fields where elevated levels of
F. graminearum are known or suspected to occur.
• Increase seeding rates to promote a more uniform stand,
reduced tillering and a shorter flowering period for the
crop. This approach helps reduce the period the crop
is flowering, which is the growth stage most at risk for
infection.
• Stagger planting dates to avoid having all cereals on
the farm flowering synchronously and potentially being
exposed to weather conducive to disease development at
the same time. Humid weather during flowering (anthesis)
in wheat or heading in barley favours infection.
• Grow varieties with the best available levels of resistance.
• Producers growing small grain cereals under irrigation
may reduce the risk of head and seed infection through
careful water management.
• When an elevated risk of FHB is suspected, consider using
a well-timed fungicide application for FHB management.
• In mature crops where FHB has occurred, adjust combines
to blow out Fusarium-damaged wheat kernels (which are
lighter than other seeds) and infected chaff to improve
the grade and reduce toxin levels in harvested grain,
especially for wheat.
• Thorough chopping and uniform spread and distribution
of straw may encourage more rapid decomposition of
infested crop residue.
• Remove loose crop residue from all equipment before
leaving an infested field.
• Control volunteer cereals and grassy weeds on infested
land, including headlands.
from harvested grain. Nearly all management tools must be
implemented prior to seeing symptoms.”
Ultimately, producers must take an integrated approach that
employs as many tools as possible. “For diseases like blackleg
or scald, there are highly effective management techniques to
mitigate the risk,” said Turkington. “With F. graminearum, you
can use all the tools and still have significant yield loss, grade
reduction and mycotoxins.”
Durumdilemma
As if the basic challenges presented by F. graminearum weren’t
enough, the obstacles to effective management are even
greater when it comes to durum.
“Durum has historically been very susceptible,” said
Agriculture and Agri-Food Canada (AAFC) research scientist
Ruan Yuefeng.
“F. graminearum is generally assessed in terms of incidence
(number of spikes affected), severity (amount of spike tissue
involved with the disease) and the effects on the grain, which
we measure as a proportion of Fusarium-damaged kernels,”
added Yuefeng’s colleague, AAFC biotechnologist Ron Knox.
“Durum tends to be higher in all three aspects.”
Both men stressed the importance of selecting the most
resistant varieties of durum. “Even though they can get infected
as well, you want to reduce the favourability of conditions for
the disease,” Knox said.
Seeds of discontent
One sector being hit hard by F. graminearum is the seed
industry, which is being hurt by the disease itself as well as the
provincial regulations designed to control its spread.
“With current regulations having zero tolerance for
F. graminearum, samples must be treated and cleaned for the
disease, leaving less genetic material to go around,” said Kelly
Chambers, executive director of the Alberta Seed Growers.
“Even if the seed goes in clean, unless it’s a resistant variety
you likely have inoculants sitting in the soil,” she added.
“Under the right conditions, you will have F. graminearum
develop, and without the province recognizing that, it
impedes the education process.”
Consequently, Chambers said producers feel they don’t
have to worry about the disease and may manage accordingly,
causing it to spread more rapidly.
One of the best tools for controlling the disease’s spread is
the use of Fusarium-resistant varieties, but that is easier said than
done in Alberta’s regulatory environment.
“Unfortunately, it’s that chicken-and-egg dilemma. If we
stick our heads in the sand and say ‘zero tolerance,’ we won’t
open doors for genetics coming to Alberta that could offer
resistance,” she said. “It’s perceived that we don’t need
those genetics because we don’t have Fusarium here, so the
provincial stance is a big obstacle to combating this disease.”