Sclerotinia always lets us down, doesn’t it? For a disease, it really is the pits.
For instance, you can’t see it in your paddock until it’s too late. You think you’re going okay, until it’s everywhere. And even when you’re doing the right thing and rotating your crops, those black sclerotia lumps can survive for up to 10 years in the soil, forever threatening future canola crops… such a pain.
At least today, we’re here to tell you there’s some silver lining to this disease. In a paper recently published in Molecular Plant Pathology (scroll down for link), CCDM researchers were able to confirm the pathogen causing sclerotina has the ability to infect more than 400 different plants.
While that might sound like a lot, CCDM researcher Mark Derbyshire says there is a positive side to this, because at least the disease has decided to stay well away from our cereals.
“Despite the fact it infects so many different species, it’s quite restricted in that it can only infect broadleaf plants such as canola, chickpea and lupins, and for some reason it doesn’t infect grasses like wheat, barley or oats,” Mark said.
“The research review also shines a light on the need to know which genes control resistance in canola plants. If we can work this out, and thankfully we’re getting much closer, we can really help growers manage this difficult disease by helping to create resistant varieties.”
Managing sclerotinia this season
Nutrien agronomist Kyran Brooks, based in Southern WA and also on the Crop Disease Podcast, said while growers are probably seeing more sclerotinia with increased plantings of canola, he didn’t think the disease had worsened in severity in his region.
“I wouldn’t say it is getting worse over time, but it is probably more noticeable with people looking for it more,” he said.
“Sclerotinia is difficult and needs a gut feel when it comes to managing it. It’s not a visual disease, when you see it it’s almost too late to act, which means you need to be on the ball and try to manage it early.”
Kyran said he would advise growers dealing with sclerotinia to become aware of what the risks of sclerotinia infection are within their rotations, and then monitor environmental conditions that are conducive to outbreaks.
“And if there is an outbreak, it’s definitely worth talking to the people who have managed it before who understand it and know the trigger points and when to pull the trigger, because it really is a decision that needs to be made prior to any visual symptoms becoming a real issue,” he said.
“Speak with researchers, read the articles, understand the key timings for applications of fungicide to manage it, and understand the high risk paddocks would be key areas I would advise growers to focus on.”
Will we ever have disease free canola?
According to Mark Derbyshire, the answer is probably no.
“Diseases are complex. If you eliminate one disease, eventually something’s going to take its place,” he said.
“And even then if you did produce sclerotinia-resistant varieties I don’t think there is a chance you’ll completely eliminate that disease, because over time it will evolve and adapt to whatever you’ve done to try and control it, and this goes for other diseases as well.
“But that’s why it’s important to continue doing the research, to try and keep up with disease problems in the field and manage them as they are at the time, and see what solutions you can put in place.”
Mark said there are currently no resistant varieties of canola in Australia, however his team are working to change this, developing better ways of breeding canola plants with sclerotinia resistance and using international collaborations to develop new resources that breeders can use to breed resistance into Australian varieties. So watch this space!
The sclerotinia review paper can be found here: https://bsppjournals.onlinelibrary.wiley.com/doi/10.1111/mpp.13221
To listen to the podcast episode on this, click here.