Many fields were seeded in odd shapes because low spots could not be reached. Growers have a challenge to manage the weeds in these patches. Options include:
Chemfallow. The product you use on the canola crop will keep down weeds early in the season, but flushes will continue to come without crop competition to keep them down.
Cultivation. Getting the cultivator in a few times over the summer could trample crop if low spots are completely cut off from field edges.
Cover crop. Chronic wet low areas could be seeded back to a perennial such as alfalfa that could be cut for hay. Trampling crop remains an issue, unless the plan is to take just one cut after canola is swathed or combined. Alfalfa is also tougher to remove if this is only a short-term plan. Greenfeed such as oats or barley might be the better option. They will provide better weed competition for this year, and may even provide a harvestable grain crop if the fall extends long enough. Otherwise they make good silage or greenfeed.