Jul 20, 2020
New cases of clubroot have been confirmed in Manitoba in 2018, with the latest distribution map for the province available at www.gov.mb.ca/agriculture/crops/plant-diseases/clubroot-distribution-in-manitoba.html. Plants with suspicious symptoms can be sent to the Manitoba Agriculture Crop Diagnostic Centre and soil samples can be sent to the Plant Surveillance Initiative Lab in Winnipeg (go to www.mbpestlab.ca for information on submitting a sample). Soil samples should be taken near approaches to fields where equipment would usually enter. These are also the same areas where the first plant symptoms are most likely to occur.
The resting spores of clubroot can survive for as long as 20 years in soil. Disease development is enhanced by moist conditions and soil temperatures in the 18 to 25?C range. Spores can survive in soils with pH from 4.5 to 8.1. Roots of infected plants form club-shaped galls which turn from white to brown as they mature. Above ground symptoms are characterised by wilting, stunting, yellowing and premature ripening.
Clubroot spreads through the movement of infested soil. Reducing soil movement on and between farms is crucial to limiting the spread of clubroot. Good sanitation for farm equipment should be utilized. A rough cleaning to remove loose and clinging soil is a good first step. A wire brush and compressed air will assist with cleaning. This will remove as much as 90% of soil, and an additional pass with a pressure washer will remove almost 99% of soil and debris. Spraying farm equipment with a 1% bleach solution is the most intensive level of sanitation. Working infested fields last, not working fields when the soil is wet, and asking custom operators to practice good sanitation will help reduce field-to-field soil movement.
A crop rotation of at least 3 years between canola crops and good control of alternate hosts such as wild mustard, stinkweed, and shepherd’s-purse will decrease the chances of clubroot establishing in a field. Clubroot resistant canola varieties add another tool to an integrated management plan for clubroot.
Please visit with your Shur-Gro agronomist for more information about clubroot and advice on management strategies.