Manitoba’s canola crop is off to a good start — so good, Angela Brackenreed doesn’t want to jinx it.
“In general I would say we have a really good looking canola crop across much of the province,” Brackenreed, the Canola Council of Canada’s Manitoba agronomy specialist, said during Manitoba Agriculture’s Westman Crop Talk webinar June 15. “It makes me nervous saying that it is really a nice-looking crop, so knock on wood.”
Canola staging varies but most is in the rosette to cabbaging out stage, she said.
On the whole Western Canada’s canola crop is also looking good, she added. The crop is most advanced in southern Alberta, followed by Manitoba and then the rest of the West.
Canola reseeding was minimal in this province and confined mainly to the south-central and northwest regions, Brackenreed said.
“In south-central it was a combination of factors — frost, high wind and flea beetles and potentially some poor establishment just because of dry conditions,” she said. “We do have some variable stands… Producers seeded a little deeper trying to hit moisture… or seeded shallow hoping for moisture and it took some time for the moisture to finally come.”
Cutworm feeding was behind some of the canola reseeding in the northwest, she said.
Many canola crops have advanced enough that flea beetles are no longer a threat and the first in-crop herbicides have been applied. But there are things to be looking for, Brackenreed said. One is the potentially yield-robbing fungal disease blackleg. Often the damage isn’t noticeable until swathing time.
“The reason I wanted to talk about it now is an early season fungicide (application) is one option for control or reduction of this disease,” she said.
“I am a little bit afraid that some spraying has taken place a little bit too late to be as effective as it potentially could be. For best control… a fungicide application has to be very early.”
To reduce application costs consider spraying combing a fungicide application with a herbicide.
“The worst loss comes from an infection (blackleg) that happens at the cotyledon to three to four leaf stage,” Brackenreed said. “So that application needs to be done at that time or prior to. The cotyledon to the two to three leaf stage would be ideal…”
Before spraying consider whether it will pay. That means assess the risk versus the cost. With a fungicide, not including the cost of application, costing $10 to $15 an acre yield must be increased by a couple of bushels an acre to breakeven.
“I would say for most of Manitoba blackleg is on the rise and has been steadily for the last number of years,” she said. “We know the risk (in Manitoba) is high.”
A lack of calm days has challenged crop sprayers this spring, Ideally herbicide spraying should be done in winds of 20 kilometres an hour or less.
“If you have to spray with winds of 20 km, gusting up to 30, you really need to know what’s downwind because that is getting a little bit risky,” Brackenreed said. “Low drift nozzles can help.”
Reducing ground speed, adjusting pressure and water volumes and lowering sprayer booms can help.
“The problem if you get too low with the booms is you may not get as good coverage.”
Root rot is a perennial problem. There might be a bit more this year due to deeper seeding.
“Unfortunately there is no real solution after-the-fact,” Brackenreed said. “But I think it is important to take note of it out in the field.”
Shallower seeding into warmer soils could reduce the problem in future years.
“Unfortunately the fungal complex that causes these root rots are so ubiquitous in our soils that rotation probably isn’t going to be all that effective, but it certainly could help to reduce that pathogen load in the soil if you were too widen out your rotation.”
Applying herbicides to a stressed canola crop can stress it even more. Plants hit twice due to spray overlap can even die. Recent rains are stressing some canola crops, especially in low areas.
“If this is a situation on your farm you may want to try and let that crop recover a little bit, although if you are trying to target your first in-crop (herbicide) application, which is really important for yields and your weeds are really getting out of control, it could potentially be worth a little bit of crop damage to get those weeds controlled,” Brackenreed said.
Water-stressed canola turns yellow because the roots are starved for oxygen, preventing the crop from taking up nutrients, including nitrogen. In most cases the nitrogen is still there and will be available when the soil dries. As a result in most cases applying more nitrogen in-crop isn’t going to help much, she said. However, it can be where the nitrogen has either leached or volatilized. But application timing is critical.
“The three to five leaf stage is when we want to be applying (nitrogen) to make sure that it is available when the crop needs it,” Brackenreed said.
Urea, liquid UAN and ammonium sulphate can all be applied to canola as a top dressing.
Urea is the most volatile form, followed by UAN and ammonium sulphate, she said. There are products that can stabilize urea and UAN.
“All these products need rain to get to the root zone,” Brackenreed said, noting canola doesn’t absorb nitrogen through its leaves.”
“if you are going to use a product like urea to top dress — and there is certainly nothing wrong with that — you want to make sure the leaves are fairly dry to try and limit those urea prills from staying on the leaf surface and causing leaf burn. With liquid actually the opposite is ideal…”