Several clubroot-tolerant canolas could be available to Alberta and other western farmers next spring.
In the meantime, Manitoba authorities have stepped up their vigilance against the long-lived, soil-borne pathogen that can decimate canola yields.
Pioneer Hi-Bred’s 45H29, the first clubroot-tolerant canola in Canada, received interim registration in February at the Western Canada Canola/Rapeseed Recommending Committee (WCC/RRC) meeting. Now Monsanto has at least two clubroot-tolerant canolas under its Dekalb brand and will ask the recommending committee in December to grant interim registrations based on what company spokesperson Trish Jordan described as the “precedent,” set last year.
Normally two years of data are required before a new canola can be recommended for registration – one year of private company data and one year from public “co-op” trials. But the rules were set aside earlier this year and 45H29 was granted a three-year interim registration based on the emergency created by clubroot in the heavy-infested areas around Edmonton.
“We believe the presence of clubroot on Alberta farms is an ongoing emergency situation for growers and they need access to solutions that are widely available from as many seed suppliers as possible,” Cornie Thiessen, Dekalb’s brand business manager for Western Canada said in a news release. “Growers like to have choices when it comes to purchasing seed and we would like to see those choices become more readily available to them.”
Other companies are working on clubroot-tolerant canolas too and might also request interim registrations in December, said Neil Arbuckle, Monsanto’s western marketing lead for seed and traits.
Monsanto’s request for interim registrations could be moot if the Canola Council of Canada’s proposal to make interim registrations more available is approved by the WCC/RCC.
(See story on page 15.)
Clubroot, which was first detected in Alberta canola fields in 2003, has not been found in any commercial canola fields in Manitoba yet, said Anastasia Kubinec, Manitoba Agriculture, Food and Rural Initiatives’ (MAFRI) oilseed specialist. In 2005 infected canola was found, appropriately enough, in a disease nursery in Manitoba. Canola was not planted in the plot again and clubroot spores, which can survive up to 20 years, have not been found, Kubinec said.
Meanwhile, Agriculture and Agri-Food Canada and MAFRI expanded their canola disease survey this year, including taking random soil samples from 60 fields to look for clubroot spores. Surveyors didn’t spot any clubroot symptoms.
Clubroot was confirmed in Manitoba rutabagas in the 1920s and there were anecdotal reports of the disease in brassica vegetable crops in the 1980s, Kubinec said.
45H29 seed will be more widely available next spring, said Dave Harwood, Pioneer’s technical services manager.
“By all indications it is one of the best products in our lineup in all respects,” he said, noting sometimes a new variety with a specific disease resistance trait is weaker in other areas.
45H29, while tolerant to clubroot, can still be infected by the disease, Harwood said.
45H29 is a hybrid and resistant to the Roundup herbicide.
Monsanto’s (Dekalb) new clubroot-tolerant varieties are also hybrids and Roundup Ready.
While Pioneer and Monsanto’s varieties are generically modified, the clubroot tolerance was introduced using conventional plant-breeding techniques.
Presumably clubroottolerant canolas will cost more than ordinary canola so in most cases it won’t make sense to grow them in areas where clubroot is not a threat, said Derwyn Hammond, an agronomist with the Canola Council of Canada.
Where clubroot is a problem, farmers should still grow canola only once every four or five years.
“If you go back to tight rotations because you have the genetics, you create selection pressure for strains that may overcome the tolerance and we don’t want to lose that tool,” he said.
Clubroot, Plasmodiophora brassicae Woronin, was in the past classified as a slime mould fungus (myxomycete), but now it’s considered a protist – an organism with plant, animal and fungal characteristics, according to Alberta Agriculture’s website.
Symptoms vary with the timing of infection. Infection at the seedling stage causes wilting, stunting and yellowing of canola plants in the late-rosette to early-podding stage. Later infections cause premature ripening and seeds will shrivel.
Farmers shouldn’t assume premature ripening is caused by more traditional diseases such as sclerotinia. If they spot symptoms farmers need to check the roots.
Since the disease spreads through soil, farmers in infected areas are urged to clean equipment between fields.
Infected “clubbed roots” produce resting spores, which germinate in the spring producing zoospores that swim in soil water to root hairs, infecting the plant, Alberta Agriculture’s website says.
After the initial infection a second generation of zoospores reinfects the roots of the initial host or nearby plants and are able to invade the cortex (interior) of the root. Once in the cortex, the amoeba-like cells multiply or join with others to form a secondary plasmodium. As this plasmodium develops, plant hormones are altered, which causes the infected cortical cells to swell and make galls. These produce another generation of resting spores and the cycle repeats. Resting spores can survive up to 20 years in the soil.
Clubroot was first identified in Europe in the 13th century. It’s a serious problem in cole crops in British Columbia, Quebec, Ontario and the Atlantic provinces.