Ron Howard, plant pathology research scientist for Alberta Agriculture’s Crop Diversification Centre in Brooks, was one of several guest speakers offering insight at the April 2 clubroot workshop, held at Club Alouette in Falher.

The emergence of clubroot – Plasmodiophora brassicae – is becoming a serious cause for concern among agricultural producers in central Alberta. And the province’s department of Agriculture & Rural Development is hoping that education, combined with preventative reinforcement, will go a long way towards stopping the aggressive soil-born plant pathogen dead in its tracks. That was the message stemming from a clubroot information meeting April 2 at Club Alouette in Falher which attracted an estimated 60 people from around the Smoky River region. “Clubroot occurs worldwide where crucifers are grown,” says Ron Howard, plant pathology research scientist for Alberta Agriculture’s Crop Diversification Centre in Brooks, AB. “Principal hosts are typically cole crop vegetables, canola, mustard and cruciferous weeds.” Howard was one of two guest speakers invited to share their expertise about clubroot last week. Joining him for the afternoon information session was Dr. Habibur Rahman of the University of Alberta, and Erin Brock from the Canola Council of Canada. Of significant interest to Howard, Rahman and other experts in the past couple of years has been the spread of clubroot from major areas of infestation including Ontario, Quebec, the Atlantic region and British Columbia into Alberta. The first real sign of a clubroot problem in the province came in 2001 when a rather heavy infestation was observed in cabbage at a market garden in the Leduc area. Two years later, in 2003, it was found in 12 fields northwest of Edmonton in Sturgeon County. That figure grew to 41 fields in four central-Alberta counties by 2005 and 113 fields in six counties the next year. By last year clubroot expanded once again, this time to include 171 fields in 11 counties in central and southern parts of the province. And that fails to account for an additional 79 infected fields reported by Agricultural Fieldmen. “A grand total of 250 canola fields in Alberta were clubroot infested in 2007 based on disease surveys. Clubroot was added as a pest to the Agricultural Pests Act (APA) in April of 2007. The APA is the foundation legislation for enforcement of control measures dealing with designated pests in the province. Clubroot gets its name from the formation of club-like multi-lobed root galls which form on roots and contain large quantities of resting spores that infect plants. Resting spores germinate in the spring, producing zoospores which swim in soil water to root hairs. These resting spores have a half life span of about four years but can survive for up to 20 years. After the initial infection through root hairs or wounds, the pathogen forms an amoeba-like cell which quickly multiplies and joins with others to form a plasmodium. The plasmodium divides to form secondary zoospores that re-infect the plant, and can also move into nearby plants. As the secondary infection develops, plant hormones are altered causing the infected cortical cells to swell into clusters called “clubs” or galls. These clubs essentially starve the plant by significantly reducing the roots ability to transport sufficient water and nutrients to the plant parts above ground. When the secondary plasmodium matures, it divides into millions of resting spores which remain in the soil, waiting for susceptible plants to infect. The expanding presence of clubroot in Alberta has resulted in the development of a province-wide management plan to try and put the brakes on the disease. “The purpose of the plan is to minimize the build-up and spread of clubroot and reduce the risk of yield and quality losses in host crops,” says Howard. That process starts with an effective farm equipment sanitation program which involves removing soil and plant debris from equipment, cleaning dirty surfaces by washing and/or using compressed air as well as applying a disinfected to the clean surfaces. Howard adds that since clubroot infestations are still not widely distributed in Alberta, various precautionary measures should be taken by producers to curb the spread of this disease. “Growers need to be vigilant to prevent the introduction of clubroot to clean fields because few economic options currently exist to control infestations in canola,” Howard explains. “At this time, clubroot cannot be eradicated and must be managed,” says Howard, adding that education and prevention is the key in terms of limiting future damage to Alberta crops. Producers are urged to use longer rotations between successive crops of canola, mustard and cruciferous vegetables when addressing clubroot infestations. That includes a three to five-year rotation for light infestations or six to eight years for moderate to heavy infestations. Producers in the Smoky River region are also urged to regularly scout their fields and be on the lookout for signs of clubroot. “Most heavily infested fields in Alberta have generally occurred in canola-canola and canola-cereal-canola-cereal rotations,” Howard explains. Dr. Habibur Rahman of the University of Alberta outlined the breeding research he is involved with which is trying to introduce clubroot resistance into canola. The U of A is implementing several breeding programs involving related plants such as rutabaga, turnip and winter canola, where clubroot resistance already exists. The hope is that resistance will be introduced into commercial spring canola varieties within five years. Erin Brock, Agronomy Specialist with the Canola Council presented on the devastation she had seen from the disease while working for Parkland County (west of Edmonton) coordinating their clubroot inspection & awareness program. The Falher meeting was the first of four meetings held in the Peace Region by Municipal Agricultural Service Boards and their Agricultural Fieldmen. A meeting was also held in Rycroft the evening of April 2, with Fairview & Grande Prairie holding meetings April 3. The A.S.B’s and Agricultural Fieldmen of the Peace region hope the area farmers view clubroot as a potentially devastating disease, and take measures such as sanitizing equipment brought in from outside the region and ensuring contractors and construction equipment is cleaned before being allowed on their land. For more information on clubroot contact your local agricultural fieldman or log on to the Government of Alberta’s website at: www1.agric.gov.ab.ca