Canola benefits from both early seeding and early weed control. The solution: Work through seeding and spraying operations simultaneously. Have the seeder working when it can. Meanwhile walk fields to get an indication of weed pressure. Fields with large numbers of winter annual and perennial weeds should get a pre-seed burnoff. While spraying that field and waiting 3 days to seed, other fields that don’t have serious weed issues can be seeded and then sprayed after emergence.
The top graph from AARD in Alberta uses crop insurance data from 2002 to 2011 showing the relationship between seeding date and yield. Click here for graphs from other soil zones.
The bottom graph is based on MASC Manitoba crop insurance data, showing the relationship between seeding date and relative yield for multiple crops. Here is more Manitoba seeding date data on canola specifically. Given the rapid change in weather over the past week, canola growers may be encouraged to know that Manitoba growers have seeded 42% of the canola crop in a single week, given good conditions.
Manpower is an issue on many farms, especially when finding a way to seed and spray in the same small window. In that case, there may be good return on investment to hire a custom sprayer to take care of pre-seed burnoff in fields that clearly need it.