Variety Registration
For seed to be legally sold in Canada, varieties of Brassica napus (canola and/or oilseed rape) must be registered with the Variety Registration Office under the authority of the Seeds Act. Candidate varieties are tested for certain merit criteria according to guidelines set by the various Canadian canola recommending committees. The Ontario Canola Recommending Committee (OCRC) is responsible for Brassica napus recommendations for registration in Ontario. More information about the committee can be found at www.GoCrops.ca. Although OCRC are authorized to recommend spring canola varieties for registration, most spring canola variety recommendation in Canada is pursued through the Western Canada Canola/Rapeseed Recommending Committee (WCCRCC).
The merit of a candidate variety is tested according to the recommending committee’s guidelines. Field trials must be conducted under specific criteria and inspected by the committee. Field trials are conducted to collect yield data as a part of the merit criteria, and to collect grain to test its quality. There are additional factors to consider, but in general a variety that meets the recommending committees yield and quality standards can be recommended for registration. Following these approvals, seed companies then seek registration with the Variety Registration Office.
Variety Selection and Traits
Seed dealers provide information on yield and traits of varieties available to Ontario spring canola producers. Performance trials are no longer conducted in Ontario or Western Canada.
Producers should select varieties with an appropriate maturity for their region. Aside from yield, other canola traits to consider include:
- herbicide system (e.g., Liberty Link, Roundup Ready)
- disease resistance (e.g., clubroot, blackleg etc.)
- resistance to pod shatter
- low percentage of green and brown seeds
Most canola grown in Ontario is tolerant to either glufosinate (Liberty) or glyphosate herbicides, or both. These varieties are transgenic (contain genetic material from an unrelated organism) and were developed by genetic modification technology. There are also varieties tolerant to imidazolinone herbicides (Clearfield – IMI tolerant), with imazethapyr, the active ingredient in Pursuit being the most common. IMI tolerant varieties were developed through natural selection of mutations from conventional varieties and are non-transgenic.
Select varieties genetically adapted to low green and brown seed count. The length of the growing season and weather stress during seed fill has the largest impact on green and brown seed, but genetics also play a role. If the seeds are green or brown inside (pale yellow is normal) when crushed the oil quality and ultimate market value of the canola are affected, so presence of green and brown seed can cause down-grading or rejection of canola.
Ontario is a small market for canola compared to other parts of Canada, and seed companies typically only make a few spring canola varieties available each season. Ontario producers typically select varieties with an appropriate maturity for their region that have clubroot resistance and pod-shatter tolerance.
Clubroot Resistance
Clubroot has been observed in canola crops or detected in soils in most canola growing regions of Ontario. Therefore, Ontario producers should select varieties with clubroot resistance. Clubroot spore levels in a field increase each time a susceptible host plant is grown in the field which makes future management of the disease more difficult.
While there may be a predominate pathotype in a field, the population of clubroot spores in a field will include different pathotypes or strains of clubroot. Resistant varieties are only resistant to specific pathotypes; there are no clubroot resistant varieties that are effective against all pathotypes. Pathotypes that are not controlled by a resistant variety will proliferate in a field where a resistant variety is grown. It is ideal to grow resistant varieties before clubroot spores appear in a field to avoid high spore loads developing and increasing the probability of pathogen shifts which can bypass resistant varieties. To preserve the effectiveness of resistant varieties they should be used in combination with other clubroot management practices, including:
- long crop rotations (canola once every 3 or 4 years)
- controlling volunteer canola and weed species from the Brassica family within 3 weeks of emergence
- limiting activities that introduce foreign soil into the field
- diligent scouting for clubroot
Canola varieties are labelled as resistant if they are resistant to the predominant pathotypes in Western Canada. Additional ratings are applied to note resistance to uncommon or new pathotypes. There are currently no commercial tests to determine the predominant pathotype in a field or detect new virulent strains. Producers do not have enough information to effectively rotate varieties with different genes with resistance to the predominant pathotypes in their field.
Clubroot-infected plants may be found sporadically in a field planted to a resistant variety. Bags of hybrid canola seed contain off-types that are not clubroot resistant, and volunteers may be present in a field. Off-types are a normal part of hybrid seed production. If clubroot-infected plants appear in a patch that is a good indication that there is a pathotype in the field that has overcome or bypassed the resistant variety.