{"id":103523,"date":"2025-08-28T16:05:12","date_gmt":"2025-08-28T16:05:12","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/103523\/"},"modified":"2025-08-28T16:05:12","modified_gmt":"2025-08-28T16:05:12","slug":"verticillium-may-undermine-canola-blackleg-resistance-2","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/103523\/","title":{"rendered":"Verticillium may undermine canola blackleg resistance"},"content":{"rendered":"

Emerging research suggests a troubling twist in canola disease management: When verticillium stripe is present in a field, the resistance to blackleg built into many canola cultivars appears to break down.<\/p>\n

\u201cWhat we have discovered very recently is that not only do these two pathogens cause disease, but they interact in such a way that the disease is increased, even when you grow a blackleg resistant canola variety,\u201d University of Manitoba plant science professor Dilantha Fernando said. \u201cIt appears blackleg resistance cannot be maintained in the presence of the verticillium.\u201d<\/p>\n

The finding \u2014 first seen in greenhouse trials and now being tested in the field in plot at Carman, Man. \u2014 suggests that even varieties carrying strong blackleg resistance genes<\/a> might suffer heavier damage if verticillium stripe is also present in the field.<\/p>\n

\t<\/p>\n

Read Also<\/p>\n

\"Kaeley<\/p>\n

Canola micronutrients under microscope<\/p>\n

Study aims to shed light on micronutrient fertilizer claims for lesser-known canola crop nutrients like boron, copper and zinc <\/p>\n

<\/a><\/p>\n

WHY IT MATTERS: Manitoba is ground zero for canola\u2019s verticillium stripe<\/a> issues in Canada. <\/p>\n

Fernando\u2019s research suggests that interaction between the two diseases could hurt yields more than either disease alone.<\/p>\n

\u201cThe work in the greenhouse has shown this interaction,\u201d he said.<\/p>\n

Other work has hinted at the same pattern. A recent study using blackleg-resistant hybrids (45H31 and CS2000) found that co-inoculation with the two disease pathogens increased blackleg severity and yield loss. In that case, the hybrids\u2019 resistance mostly held. Fernando\u2019s results point to a more complete breakdown.<\/p>\n

Double trouble<\/p>\n

Blackleg (Leptosphaeria maculans), a serious fungal disease of canola, has been spreading through the Prairies since it was first confirmed in northeast Saskatchewan in 1975. Genetics are a key tool keeping the disease in check, although experts in recent years have noted virulence changes complicating some of those resistance ratings.<\/p>\n

\"AA key indicator for blackleg is a distinct black wedge in the root cortex. If there\u2019s a grayish-hue and starburst pattern in the root cortex, then it\u2019s likely verticillium stripe. Photo: Canola Council of Canada<\/p>\n

Verticillium stripe<\/a> (Verticillium longisporum) is newer. The stem-degrading, yield-reducing disease was first found in Manitoba in 2014 and has since spread into Saskatchewan. There are no varieties registered as resistant to verticillium, although seed companies are playing with varieties that seem more tolerant, and recent Manitoba research may have a line on a physical plant trait that may make infection more difficult.<\/p>\n

Both diseases are common in Manitoba. Last year, the province\u2019s canola disease survey<\/a> found basal blackleg infections in 77 per cent of surveyed fields, stem blackleg infections in 58 per cent of fields and verticillium stripe in 60 per cent of fields.<\/p>\n

Greenhouse to farm<\/p>\n

While in the greenhouse, Fernando\u2019s team was able to methodically test the disease interaction with blackleg resistance genes commonly used in Canadian canola,<\/p>\n

So far, he said, his team hasn\u2019t seen a single Canadian R gene that performs well when verticillium is also present. And while Fernando admits the number of R genes in his collection is limited, he\u2019s certain about what he\u2019s been observing.<\/p>\n

\u201cIn a fairly confident way, I can say that the R genes that are available are not standing up well,\u201d he said.<\/p>\n

Still, greenhouse trials and the reality of the field are different things. Fernando wanted a real-world test.<\/p>\n

He got the chance this year. Since 2014, Carman\u2019s research station had enforced strict protocols to keep verticillium out \u2014 boot cleaning, washing equipment and avoiding suspect fields. \u201cThis was very well followed. But as a plant pathologist, I knew that that is not going to be clean forever,\u201d Fernando said.<\/p>\n

\"AA canola stem infected by verticillium. Often mistaken for blackleg, one identifying factor is the microsclerotia are much smaller than with blackleg.Photo: Canola Council of Canada<\/p>\n

The tiny microsclerotia on verticillium are as small as dust particles, and he suspects they could easily bypass biocontrol protocols by riding in on the wind.<\/p>\n

\u201cAll of a sudden last year, almost every field had verticillium,\u201d he noted. \u201cWe went and took samples and also collected DNA from soil. We found that the pathogen was present.\u201d<\/p>\n

It was \u201cthe best thing that could happen, happened, where now we have natural verticillium inoculum, we have natural black leg inoculum, and we can put the varieties that carry different R genes and now test for the interaction,\u201d the researcher noted.<\/p>\n

It would have been nearly impossible to run the experiment in the field if they had to inoculate plants themselves, he added. That would have required separate treatments for blackleg first, verticillium first, and then both in sequence. That approach works in the greenhouse. In the field though, natural inoculant provides a much easier way to study the interactions without researcher interference and under normal exposure pressures from a mix of pathogen profiles.<\/p>\n

The team proceeded to plant varieties with different R genes in plots where both pathogens occur naturally.<\/p>\n

The Carman station already had a qPCR (quantitative polymerase chain reaction) testing method \u2014 a DNA-based tool that can detect specific pathogens in plant or soil samples \u2014 for both blackleg and verticillium. That let Fernando\u2019s team quickly confirm that the two were often found in the same plant. They sent half the samples to an Alberta lab and kept half in Manitoba to further verify. They got identical results.<\/p>\n

They\u2019ll soon see official numbers from those field efforts. Fernando expects that by the end of August, when disease ratings are completed, they will learn whether any resistance genes were able to hold up under natural infection conditions.<\/p>\n

Caution from the canola council<\/p>\n

Chris Manchur, agronomy specialist with the Canola Council of Canada (CCC), was aware of Fernando\u2019s preliminary results.<\/p>\n

\u201cIt is too early to tell how significant of an impact this specific R-gene and verticillium interaction would have on yield in the field, but it underscores the importance of effective blackleg management to prevent any additive effects of both blackleg and verticillium stripe causing yield loss,\u201d he said.<\/p>\n

He added, however, that \u201cthese results are still early and I would look to waiting until results are replicated and verified through different tests before stating this as a significant development.\u201d<\/p>\n

Manchur advised farmers make sure they\u2019ve brushed up on their disease identification skills. \u201cBlackleg and verticillium can occur together, but the CCC has resources to help identify the diseases in the field. If you\u2019re still unsure, there are options to send samples in for DNA testing,\u201d he said.<\/p>\n

\"BlacklegBlackleg microsclerotia on a canola stem. Photo: Canola Council of Canada<\/p>\n

While there are limited tools for verticillium, he said blackleg can still be managed with cultivar choice, seed treatments, and foliar fungicides at the two-leaf stage.<\/p>\n

Looking ahead<\/p>\n

Fernando\u2019s work will continue through 2025 with more Carman trials, pathogen tracking and gene-expression studies. Assuming the team gets similar field results as their greenhouse trials, they face the future question of why the interaction is having such a result.<\/p>\n

They\u2019re already running tests in a controlled environment \u2014 inoculating with blackleg first, verticillium first, and both at once \u2014 and using fluorescently tagged strains to track how each pathogen moves inside the plant. They plan to use transcriptomic analysis (the study of all RNA messages a cell makes to see which genes are active at a given time) to see which plant genes are disrupted.<\/p>\n

Fernando is also interested in the potential of targeting what are known as susceptibility genes \u2014 plant genes that actually help pathogens infect. Knocking those out could make plants tougher, even without adding new resistance genes.<\/p>\n

\u201cIt is going to be one step at a time,\u201d he said, adding that, \u201cby the end of July next year, we should have a very good handle on what\u2019s going on.\u201d<\/p>\n

\"\"<\/p>\n

Crops, markets, industry and policy, livestock production news and information\u2014delivered to your inbox 6 days a week!<\/p>\n

<\/p>\n","protected":false},"excerpt":{"rendered":"Emerging research suggests a troubling twist in canola disease management: When verticillium stripe is present in a field,…\n","protected":false},"author":2,"featured_media":103524,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[59514,49,48,10748,53583,66,59515],"class_list":{"0":"post-103523","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-blackleg","9":"tag-ca","10":"tag-canada","11":"tag-canola","12":"tag-crop-disease","13":"tag-science","14":"tag-verticillium"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/103523","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=103523"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/103523\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/103524"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=103523"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=103523"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=103523"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}