Posts Tagged ‘clubroot’

Update on Clubroot in Alberta

Wednesday, February 15th, 2012

Clubroot first appeared in Alberta in home gardens in the 1970s. In 2003, the disease was found in canola in 12 fields in Sturgeon County, northwest of Edmonton. From that time, a number of surveys have been conducted to monitor this disease. To date, over 6000 canola and vegetable fields have been surveyed, and clubroot has been confirmed in at least 830 fields in the province. Maps showing the affected areas and the spread of the disease over the years have been uploaded to the Alberta Agriculture website.
“Clubroot is an endemic disease, certainly in central Alberta,” says Dr. Ron Howard, plant pathology research scientist with Alberta Agriculture and Rural Development. “The disease is spreading by a variety of mechanisms and management is difficult. The number of new cases in 2011 (265 fields), represents the biggest single year increase in clubroot confirmed fields since 2003. The abundant rainfall we received last year was no doubt a contributing factor that favoured infection and disease development. Weather conditions have a huge effect on this disease, so in years, such as last year, where conditions are very wet, the incidence of the disease increases.”

Clubroot is a significant economic threat to the canola industry and was included as a declared pest under the Agricultural Pests Act in 2007. The disease is very difficult to control once it becomes established in a field. It decreases yield in canola and also poses a risk to mustard and cole crop vegetables in the province.

Clubroot management strategies include:

  • removing soil and crop debris from equipment and machinery moving out of infested fields
  • using direct seeding or minimum-tillage cropping methods, which reduces the movement of soil during tillage operations and reduces stirring the soil and the spread of the disease
  • using long rotations between successive crops of canola to allow the pathogen population to decline in the interval
  • avoiding spreading straw, hay, greenfeed, silage crops harvested from clubroot infested fields onto clean fields because of earth tag which can carry the disease
  • NOT spreading manure from cattle fed with clubroot infested crops or forages on non-infested fields, as resting spores can survive passage through the gut of cattle
  • NOT using common, untreated seed harvested from clubroot infested fields because of the possibility of dust and earth tag that may contain clubroot spores, and certainly dirty seed should be avoided
  • regularly scouting canola, mustard and vegetable fields to discern the situation in the field and ensure that the disease isn’t spreading

“The advent of clubroot-resistant hybrids represents a major step forward in clubroot management,” says Howard. “The six products available seem to be standing up fairly well in clubroot infested areas. These varieties, while not completely resistant to clubroot, are not overwhelmed by the disease and yield is not reduced. It is very important to realize that even though a resistant variety is used, crop rotations of three years or more are still necessary to help slow the build-up of this disease in infested fields.”

Research is ongoing. Early on, there was very limited information on how to manage the disease in canola. Control strategies from vegetable growers were not that directly transferable. This prompted a whole line of research to look at disease management practices and to help understand the biology of the disease in canola. In 2009, the Clubroot Risk Mitigation Initiative was created using about $4 million in Growing Forward funding. This collaborative research has focused on pathology, breeding and disease management.

“An integrated approach is needed to manage this disease, including good stewardship of the resistant varieties of canola that are available,” says Howard.

Additional information on clubroot, including AgriFax and factsheets, is available on Alberta’s website at by typing clubroot into the search field.

Clubroot management: Equipment sanitation - Part 2

Thursday, December 29th, 2011

From Canola Council of Canada

Step 3: A 1% bleach solution will eradicate clubroot spores in cracks and crevices.

Step 3: Disinfection. Disinfect all openers, tires and wheels with a 1% bleach solution or surface disinfectant of equivalent strength. A 3-gallon backpack herbicide sprayer will work for this job. All areas should remain wet with the solution for 15 to 20 minutes. Step 3 alone is not effective. The first two steps are required if you plan to include the disinfection step. Time required: 2 hours or more. (Four hours or more for steps 1, 2 and 3.)

Recommendations for high risk areas

For growers in an area known to have clubroot, the following steps are recommended to reduce the risk of clubroot spread:

—Follow cleaning steps 1-3, or at least 1-2, above. This is especially important when leaving a field known to have clubroot. The more soil you clean from the unit and leave behind in the field, the more you reduce the risk of clubroot being spread.
—Work infested fields last. This reduces the risk of directly transferring contaminated soil from infested to non-infested fields and should have extra time to give drills and tillage equipment a thorough cleaning before being used again.
—Don’t work fields when wet. Wheels caked in mud are that much harder to clean.
—Ensure custom operators and anyone else entering your fields follow sanitation protocols. Don’t feel awkward about asking.
—Be responsible. Growers should tell local authorities and custom operators that clubroot has been discovered in their field. Some municipalities require this by law. In other areas, this is just a common courtesy. Consider posting “Do not enter” signs beside fields known to have clubroot.

Recommendations for low risk areas

For growers in areas where clubroot is not found:

—If in doubt, decontaminate. If using your own equipment and you know clubroot is not on your farm, decontamination may not be required.
—Ask custom operators, oil and gas company surveyors and anyone else entering your fields where they’ve been. Some of them cover wide geographic areas. If they have been in a clubroot-infested area, ask about their sanitation protocols and check that the machinery is clean.
—Make sure used equipment is clean. When buying used equipment, make sure it’s clean before it leaves the auction site or the farm it comes from. Also check that the transport truck is clean. As a precaution, you may want to pressure wash the equipment again when it gets to your farm.

Clubroot management: Equipment sanitation - Part 1

Wednesday, December 28th, 2011

From Canola Council of Canada

The most common way to transfer soil from field to field is on farm machinery and vehicle tires. The CCC has a new guide with tips to clean equipment and prevent clubroot’s spread. Click here for the full guide. The following article is a short summary of the guide. Visit for general information on clubroot.

Assess your risk

The following questions will help determine the risk of clubroot spread to your farm, or from field to field within your farm. Your answers will help you decide how much sanitation you need and when to use it.

—Do you already have clubroot in at least one field? If yes, thorough sanitation between each field may be warranted.
—Have you purchased used equipment that may have originated in clubroot infested areas? (Here’s the latest Alberta clubroot map.) If the equipment originates from a clubroot-infested area, make sure the equipment is sanitized before it comes to your farm.
—Has your equipment been used in fields in clubroot-infested areas? If so, it should be cleaned and disinfected before it comes back to your farm.
—Who has access to your land? Custom sprayers and seeders, oil and gas equipment and trucks, earth-moving and excavating machines, soil sampling trucks, fertilizer trucks, hunters, recreational vehicles and even agronomists can carry clubroot-infested soil on tires, machinery and shoes. Make sure they follow clubroot risk mitigation protocols.
—Do you use tillage? Tillage or any other farm practice that involves soil disturbance or results in frequent travel throughout a field will increase the risk of transporting clubroot-infested soil.

3 steps for equipment sanitation

Choosing a worksite. You should clean and disinfect the unit before leaving the field, and leave all contaminated soil in that field. A low-traffic grassed area near the field exit is an ideal place to sanitize equipment .

Step 1: Scraping and blowing can remove 90% of the soil on machinery.

Step 1: Rough cleaning. Use a hand scraper, wire brush or compressed air to remove loose and clinging soil and crop debris from openers, tires and wheels, and the frame. This should remove at least 90% of the soil from the unit. Time required: 1-2 hours for a 40 foot cultivator. Larger pieces of equipment, tractors and double disk units may take longer.

Step 2: Pressure washing can remove another 9% of soil.

Step 2: Fine cleaning. Use a pressure washer at 2,000 to 3,000 psi on all areas where soil can accumulate. Turbo nozzles are generally more effective at removing soil than regular nozzles. An industrial detergent may enhance the degree of soil removal. Steps 1 and 2 in combination should remove 99% of soil from the unit. Time required: 1-2 hours for a 40 foot cultivator. (2-4 hours total for steps 1 and 2.)

Clubroot Infested Areas in Alberta in 2011

Friday, November 4th, 2011

From Alberta Canola Producers Commission

Clubroot is a serious soil-borne disease of canola and is considered a declared pest under Alberta’s Agricultural Pests Act. It is not a new disease in Canada or Alberta; however, it is just in the last few years that it has been found in a number of counties in Alberta. Clubroot continues to spread and is a significant concern for Alberta producers.

download a printable pdf version of the map

for more information on clubroot visit

Additional information regarding Clubroot Disease of Canola and Mustard is available on-line from Alberta Agriculture

For more information about the content of this document, contact Alberta’s Provincial Oilseed Specialist Murray Hartman.

Cumulative clubroot infestations as of November 2011 from University of Alberta, Alberta Agriculture and county surveys. November 2011 map is preliminary since the survey compilation is not quite complete.

Spread residue evenly in fields planned for canola in 2012

Tuesday, October 18th, 2011

From Canola Council of Canada

Good canola stand establishment, especially in direct seeding situations, starts with straw and chaff management for the previous crop. Spreading residue evenly across the field is critical.

If the combine can’t spread cereal chaff and straw evenly across the width of cut, one option is to drop the straw and bale it. Another option is to use a heavy harrow to spread the straw. Delay heavy harrowing until the straw is dry enough to allow even distribution and minimize piling up and bunching of the straw.

One exception to this strategy for managing crop residue may be fields where a small patch of clubroot has been identified, as heavy harrowing may move enough infested soil to spread those clubroot spores throughout the field.

Click here for the library of residue management articles from the Reduced Tillage Linkages website.

Planning for next year

Monday, September 26th, 2011

Harvest is a good time to assess your canola results and prep fields for canola in 2012. If yields were disappointing given the large biomass of the crop, take time now to check for clues as to why.

From Canola Council of Canada

What was your plant count? Determine the average number of canola stalks per square foot or metre to get a better sense of the plant population that survived to swathing. Low populations may have led to bigger, branchier plants. In this case, many of these side branches may not have matured completely leading to smaller seed size or shriveled seeds that were blown out the back of the combine.

Did the crop run out of nutrients? The crop may have used up available nutrients to build biomass, especially with good rains early, and didn’t have enough left to meet seed yield potential. A fall soil test will help answer this question. If the soil is drained, consider higher nutrient rates for canola fields next year, based on soil test residual levels plus fertilizer applications.

Are all pods present and filled? Take a look at the plants before or during combining. A large swath doesn’t necessarily mean a high number of pods were produced or that they were filled properly. Missing pods could indicate environmental stress (heat blast, frost), stress from delayed herbicide applications or insect damage to pods or flowers. Short or poorly filled pods could be more likely to result from nutrient deficiency later in the season, although environmental stress could be a factor as well. Smaller seed with reddish seed coats are often a sign of late season heat and drought.

Look for disease. Clubroot, sclerotinia and blackleg can be responsible for yield losses. Clubroot severity seems fairly high this fall in traditional clubroot areas and higher than expected in some newer areas. This suggests that the disease has been present in some of these “newly infected” fields for at least one previous canola rotation, maybe two. Symptoms are not always evident above ground. Random surveying in high risk areas uncovered clubroot galls on plants that looked healthy. Growers with previously unaffected fields in regions bordering areas known to have clubroot should take a close look at their canola fields, including a thorough inspection of the roots for signs of clubroot galls. Growers in all regions should include a regular inspection of their canola’s roots as part of their regular scouting program. Discovering clubroot early will help prevent or delay its spread throughout the farm. A combination of machinery sanitation, crop rotation and variety selection can limit its spread and impact on future canola crops in affected fields. In wheat fields planned for canola in 2012, look for clubroot galls on volunteer canola or related weeds.

Clubroot galls can be found on plants that don’t show above-ground signs of disease.

For general information on clubroot and some good examples of galls at various stages of development check out this video.
For tips on identifying possible clubroot affected areas in fields and sampling techniques click here.
For tips on scouting for clubroot during or following swathing click here.
For tips on using resistant varieties as part of your clubroot management strategy click here.

Look for cabbage seedpod weevil holes in pods. With the expansion of the range of the cabbage seedpod weevil eastward in Saskatchewan, some growers may be encountering the weevil for the first time. A survey conducted annually in Saskatchewan provides approximate areas of weevil presence and level of infestations, but it is not possible to sample all fields. At harvest time, look for exit holes caused by larvae emerging from canola pods. Presence of these holes should be a warning for growers to scout for the weevil next year. See the photos below. Click here for the 2010 map.

Look for cabbage seedpod weevil holes and larvae in canola pods. If you find them, remember to scout for adults next year. Photo credit: Saskatchewan Ministry of Agriculture

Issues of the week

Friday, September 9th, 2011

From Canola Council of Canada

Warm days forecast for the coming week will give later canola crops a good chance to ripen further before swathing. If growers have a lot of canola to swath and feel they must swath something, go with the most mature crop first. On hot days, swath in the evening to give plants time to dry down slowly and let the green clearing processes function properly.

Swathing is a good time to flag large weed patches. If these patches surprise you, consider what contributed to these escapes. Are these particular species a challenge for your preferred herbicide tolerance system to control? Could they be resistant to certain herbicide groups? Or did stressful conditions contribute to reduced efficacy or poor crop competition for later emerging weeds? Identifying and recording the location of these weeds at swathing will help you with a management plan for next year.

Swathing is also a good time to scout for disease outbreaks. Clubroot incidence seems to be increasing this year, and spotting the disease now will give growers a chance to implement containment strategies.

When combining in hot conditions, put canola on aeration right away to cool it down. Also check any canola that was binned hot in the past few weeks. It should also be on aeration. Even canola at 8% moisture can start to heat if stored hot.

Crack open pods before swathing

Tuesday, September 6th, 2011

From Canola Council of Canada

Just because pods look dry and mature does not mean the seeds are ready for swathing. Sunscald and diseases such as blackleg, sclerotinia and clubroot can make plants look mature but the seeds may still be green. (Click here for an audio interview with more tips.) The opposite can also happen where pods look green but the seeds inside are ready for swathing. When assessing a canola crop to see if it’s ready, crack open pods on a number of plants throughout the field. Swathing timing is based on seed color change, not pod color. (Click here for a video description.)

Odd maturity patterns. Some growers have found canola with mature seed in pods at the top of the main stem but green seeds in pods at the bottom of the main stem. (See the photos below.) This is backwards. This reversed progression could be a response to moisture stress or some other environmental factor, such as hail damage. In this case, look at whole plants before making the swath timing decision. Don’t swath too early.

Base the decision on what is best for highest yield. Look where your yield is coming from. Is it the main stem or side branches? Is it those early ripening upper pods or the ones lower on the main stems and branches? Once that is determined, hold off swathing as long as possible to let more seeds in those areas firm up and turn color. By waiting, you may sacrifice some yield in mature pods but the highest yielding parts of the plant have a chance to finish. The final consideration is frost. If frost is forecast, you may need to swath now to preserve what’s there.

Seeds in top pods are more mature than in bottom pods on main stem. Source: Devin PendreeA wider shot showing more pods from the same main stem. Source: Devin Pendree

A wider shot showing more pods from the same main stem. Source: Devin Pendree

Tips to prepare for harvest

Monday, August 8th, 2011

From Canola Council of Canada

Many crops are nearing the end of flowering or podding. Harvest decisions should be contemplated in the coming weeks. The following are tips to consider during the lead up to harvest.

1.    Scout for disease prior to swathing. Assess levels to determine if premature ripening or pod damage is due to diseases like blackleg, sclerotinia stem rot, clubroot, or alternaria and may necessitate swathing earlier than normal – before seed shatter starts. It is important to determine which of these diseases is present in your field for future rotation planning. If blackleg or clubroot is found, then rotations should be lengthened to prevent the disease from building up and threatening neighboring fields and the effectiveness of our genetic resistance. If the disease is sclerotinia, then an assessment of the % of infected plants will help determine the yield loss and an estimation of whether fungicide applications would have been warranted. Click here for the disease assessment card.  Fields with lots of diseased plants will be poorer candidates for straight cutting due to the increased shattering risk.

2.    Hail damage can cause crops to mature unevenly. When swathing a hailed crop, assess the seed-colour change at the earliest and highest-producing parts of the field, especially if the delayed maturity creates a high risk for fall frost damage.

3.    Check weed pressure. Green biomass in the swath will extend the curing time, and weed seeds and green plant material can be starting points for heating in storage. Fields with high weed counts may benefit from a pre-harvest spray to dry them down.

4.    When to swath. The best timing for yield and quality is when 50% to 60% of seeds on the main stem are turning from green to brown. Click here for a time of swathing video.

5.    Lay swaths parallel to the direction of prevailing winds to reduce the odds of cross winds flipping swaths. This reduces the risk of swaths blowing and pods shattering.

6.    Set the roller low enough to anchor swath into standing stubble with slight pressure. Use a roller that tucks swath edges down into stubble.

7. Large dense swaths tend to take longer to condition and cure canola before combining. Thin swaths lying flat on the ground may also take longer.

8. Straight combining tends to work best on thick stands with plants meshed together to prevent whipping in the wind.

9. Tune up the combine with lots of tips from the recent combine clinic in Alberta.

How much canola is too much?

Wednesday, March 24th, 2010

With disappointing prices for cereal grains, many producers in the prime canola growing regions are struggling with whether to tighten their canola rotations. Some producers grow canola every fourth year and that would be in line with recommended agronomic practices. Other producers have a third of their acres in canola each year. Some producers have half of their acres in canola and a few producers actually grow some canola on canola stubble. With canola returns likely to be substantially higher than wheat, barley or oats, there’s a strong incentive to throw agronomic guidelines out the window. As producers tighten their canola rotations, are they flirting with more disease issues? Clubroot in Alberta has been a major scare for the industry. As well, there are worries that more virulent strains of blackleg will be promoted. Canola breeding was able to respond quite quickly with varieties that have resistance to clubroot and so far blackleg resistance has held. Producers who have followed recommended rotational guidelines have watched their neighbours tighten rotations without many adverse effects. Expect more producers to take that path this year. I’m Kevin Hursh.

If you have questions about crop rotation, ask a DynAgra Agronomist for answers. 1-800-941-4811 or visit