The impact of row spacing, seeding rate, and
fungicide timing were assessed at seven Canadian spring wheat sites in
2019. Narrow and wide row spacings (RS)
were only set up at four sites. Seeding
rates (SR) of 200 and 400 seeds m-2 were used, while fungicide (Prosaro XTR)
timings included: check no treatment; at the start of anthesis (early); a late
application date 7-10 days after the start of anthesis (late); and a dual early
and late application. Leaf spot levels
were low at four sites, while low to moderate levels occurred at the remaining
three sites. Overall in 2019, RS and its
interaction with other factors generally had limited impacts on disease, crop
productivity and kernel quality. Seeding
rate and fungicide tended to have the most frequent impacts on leaf disease and
crop productivity. Higher seeding rates
(SR) at two of seven sites increased leaf spot severity. Seeding rate also impacted yield, and
thousand kernel weight (TKW) at four and three sites, respectively. Yield was increased with increased SR at
three sites and decreased at one site.
By increasing the seeding rate TKW was decreased at two sites, but
increased at the other. In 2019,
fungicide timing impacted leaf disease and yield at three and two sites,
respectively. Here the lowest leaf disease
levels were similar for all fungicide treatments, while the highest yields
occurred for early and dual applications.
Fusarium damaged kernel severity was decreased by the increased seeding
rate at one site only. Elevated
deoxynivalenol (DON) levels only occurred at one site and were significantly
impacted by RS, the interaction of RS and SR, and fungicide timing. At this one site DON was decreased with
increased RS and SR, although there was an interaction whereby SR differences
were only significant for the narrow RS.
These observed impacts were likely due to more head emergence
variability and perhaps a wider window for infection. Fungicide timing impacted fusarium damaged
kernel severity at three sites and DON levels at one site. Overall, FDK and DON levels were generally lowest for
the dual application treatment, intermediate for single early or late
applications and highest for the check.
Although dual post-head emergence applications did impact some
parameters this treatment may be less economical, while also not being
registered for use in Canada. The
funding of the Canadian Agricultural Partnership Canadian National Wheat
Cluster and Prairie producer/industry groups is graciously acknowledged.