Investigation of management strategies to optimize cover crop-based weed mitigation in Canadian sweet corn production.

Fall sown cereal rye (Secale cereal L.) has gained popularity as a cover crop
due to its weed-suppressive capabilities. When mechanically terminated with a
roller-crimper, this method of weed control makes an inexpensive enhancement
to an integrative weed management program. Research has shown that early
milk, occurring in mid-July, is the optimal stage for cereal rye termination via
roller-crimper. However, roller-crimping at this timing would cause significant
delays in cash crop planting, potentially compromising yields. Therefore, the
objective of this research was to identify an earlier maturing cereal rye cultivar.
Two cereal rye cultivars (early vs. standard maturity) were compared at three
seeding rates (150, 300, and 600 seeds/m2
) for their effect on rye biomass, weed
biomass, and marketable yield. The trial was conducted at Agassiz, BC,
Harrow, ON, and St. Jean-sur-Richelieu, QC in 2019 and at Harrow and St.
Jean-sur-Richelieu in 2020. Results thus far suggest that the early maturing
cereal rye cultivar reaches early milk two to seven days earlier than the standard
cultivar at Agassiz and Harrow. This suggests that earlier roller-crimping may
be possible at these locations. Cereal rye biomass was highest in the 600
seeds/m2
seeding rate but did not differ between cultivars. Additionally, rye
biomass was weakly correlated to weed biomass after crimping, however, the
strength of this relationship varied among locations and years and there was no
difference in weed control between rye cultivars at each location. Marketable
sweet corn yield was affected by cereal rye seeding rate but not rye cultivar.
Overall, cereal rye biomass, weed biomass after roller-crimping, and
marketable sweet corn yield differed among locations and years. These findings
emphasize the complexity of roller-crimping cereal rye for weed mitigation and
the importance of multi-site-year studies to draw regionally specific
conclusions.