While there will be no getting around spraying for sclerotinia, Pioneer Hi-Bred’s sclerotinia tolerant Roundup Ready hybrid canola 45S51 proved in 2008 that it can at least make spraying more effective or buy you some wiggle room on the decision.
The summer of 2008 marked the first full field-scale testing of 45S51 in anticipation of its commercial launch for 2009. Ellis Clayton, Pioneer Hi-Bred’s technical product manager, likes what he sees in the data sets coming off the field. “We put 45S51 up against 45H26 in the trials, and the sclerotinia tolerant hybrid performed very similar to 45H26 under no sclerotinia pressure,” he says.
The choice of hybrid to compare with 45S51 is important, explains Igor Falak, research scientist with Pioneer Hi-Bred. “Because sclerotinia infects canola during a specific portion of the growth cycle, it was important to choose a hybrid with similar flowering and maturity timing,” he explains. “45H26 is a very competitive hybrid and widely used, but more importantly, for our trials, its growth closely mirrors 45S51.”
Kristin Hacault is the agronomy research manager for Pioneer Hi-Bred’s Canadian business unit, and has been combing through the yield and tolerance data from this summer’s trails. Right off the hop, it’s apparent that 45S51 significantly reduces the level of sclerotinia severity in the field. Fieldscale plots were rated to determine sclerotinia field severity and found that unsprayed (no fungicide) 45H26 showed a 21.6 per cent infection rate (per cent of plants ripening prematurely) compared to 45S51’s 7.2 per cent, she says.
But what does that reduction in visible infection translate to for yield? “Roughly 3.8 per cent more yield,” Hacault says. “When we compared the two hybrids under high levels of infection and didn’t spray a fungicide, 45S51 yielded 3.8 per cent more.” In this particular year, that translated to a two-bushel advantage for 45S51 without spraying. When the hybrids were sprayed while under high levels of infection, the yield difference between the two narrowed to less than a bushel, however both showed a more than two-bushel per acre yield improvement when sprayed. In 2008, both hybrids yielded roughly 50 bushels per acre across six locations in Manitoba and Saskatchewan where disease levels were high and a fungicide was applied.
Hacault relates 45S51’s tolerance of sclerotinia to a MR rating for blackleg. “The hybrid isn’t resistant; it’s moderately tolerant to the disease, meaning you will see some infection, but likely significantly less than any other hybrid out there. Most hybrids rank in the susceptible category to sclerotinia,” she says.
Sclerotinia tolerance comes from several sources, Falak says, and was created using traditional breeding methods. “It’s not that we haven’t tried other methods, or that other companies aren’t trying, but we were making improvements with traditional breeding so we continued.”
The original trait was picked up through germplasm banks in rapeseed material. From there, breeders then worked to improve the quality of the trait, breed the trait into canola lines and then finally into competitive, marketable canola lines. It’s been over 15 years, but Falak is pleased with the level of tolerance in this hybrid.
As for the dreaded yield drag normally associated with a selecting for a specific trait, Falak says, and Clayton’s data would attest, that 45S51 is still a competitive yielder. “This hybrid is not going to be the top yielding hybrid, no, but yields are very similar to 45H26 with no sclerotinia infection,” Clayton says.
Don’t skip a spray
What most farmers want to know of course is whether or not seeding 45S51 means they can leave the sprayer in the shed. In short, no. “This hybrid is not resistant to sclerotinia. It only has an enhanced tolerance to the disease. But it’s a great new management tool, especially for those with a lot of acres to cover or crops that are just on the edge of spraying or not. This hybrid should buy you a bit of time in making that spraying decision, or could protect some of your yield potential while you’re out there getting all the other fields done,” Clayton says.
Clayton doesn’t recommend farmers seed the hybrid on every field, but instead use it on some fields, perhaps those with a higher than average risk to heavy infection. “We don’t recommend one hybrid for any farm. Using several different varieties across the farm is just a good management tool in general,” he says.
Anastasia Kubinec, business development specialist — oilseeds, with Manitoba Agriculture, Food and Rural Initiatives, agrees with Clayton’s assessment of how 45S51 might be used in managing for sclerotinia infection. “Anything that might decrease the level of infection and amount of inoculum in the soil is a good thing,” she says. Reducing the amount of inoculum is especially important with sclerotinia because it attacks so many crops. Canola, beans and sunflowers are all susceptible to the same pathogen, Kubinec says, “We even saw sclerotinia infection on flax this year.”
Fungicide options for canola, while pricey, are relatively effective, but Kubinec is happy to see a new tool available for managing the disease. “Rotating away from canola and other susceptible crops really does have an impact on disease levels in the years following. I can’t stress the importance of crop rotations enough,” she says. She also recommends choosing a variety with good lodging tolerance, as sclerotinia loves a humid environment. The more airflow through the crop canopy the better.
As with any disease, knowing what to scout for and when to scout can make all the difference in how prepared you are to combat infection. Sclerotinia spores can be carried on the wind once released from apothecia in the soil, Kubinec says. She suggests scouting wheat and especially winter wheat, as it’s usually grown on canola stubble, in early June for apothecia. “If you’re finding a lot of apothecia then, you’ll get a sense of just how much of the disease is out there, waiting to be spread. It’ll give you a sense of what pressure adjacent fields may be under once blooming starts.”
Lyndsey Smith is a staff writer with Farm Business Communications.