Clubroot is a serious issue threatening canola production on the Canadian prairies. The disease is caused by the soil-borne protist Plasmodiophora brassicae.
Early detection of clubroot symptoms is an important aspect of management because undetected infections can lead to very high populations of resting spores in soils, which then become extremely challenging to manage or remediate.
However, soil-borne organisms, such as P. brassicae, primarily cause symptoms on roots underground which cannot be seen without destructive sampling. As a result, the number of roots that can be evaluated is limited by the time and effort required to dig them. The fact that only a tiny percentage of roots can be evaluated in a field means that most infestations are undetected until above ground symptoms appear, which is too late to prevent high resting spore populations.
A better approach to detection would be a method that allows rapid scouting of fields for below ground symptoms without destructive sampling. Canine detection of hidden substances has been used by humans for centuries. Today even skin and lung cancer can be detected by dogs. The discriminatory capacity of dogs is astonishing, detecting odors in the parts per million or even less. Remarkably, some can even detect samples previously thought to be odorless. Additionally, dogs can move through fields more rapidly than humans, can work happily for long hours in many environmental conditions, and do not require monetary compensation.
Successful examples of detector dog / dog handler teams locating items by scent include, explosives, buried victims, human remains, gas leaks, dangerous animals (snakes), termites, contraband food or products, accelerants, drugs, and money. Detector dogs have even been used to detect infections, pests or diseases by their unique scents. For example, cancers, gypsy moths, screwworms, Laurel wilt disease in avocado, bark beetles, and huanglonbing in citrus. It is reasonable to assume that this amazing ability of dogs to detect unique animals, cells and volatile compounds could be put to use in detection of clubroot.
Full breakdown of project objectives
|Select appropriate dogs for training|
|Clinically train a dog to detect clubroot using clubroot-infected materials|
|Field testing and training to confirm the dogs ability to detect clubroot in a canola field|
|Perform matrix testing - to ensure the scent is detected in many environments and conditions|
Full breakdown of project methods
Training dogs to detect clubroot
Animal selection and acquisition. Reputable dog breeders with a history of success will be considered. Specifically designed behavior/response tests will be performed to accurately measure the potential of working dogs. The end goal is an agile, confident physically fit dog needing little maintenance or correction. Brain development in dogs is complete by 42-50 days of age and selections can be made after that time. Physical development of the dog is also important to ensure that they are comfortable and capable of working in the environments required.
Acquisition of scent training materials. Clubroot infested materials will be provided from canola roots collected in the 2018 Alberta canola survey (note that pathotype 3 and 5 will be collected, but that detection of individual pathotypes is not in the scope of this project).
Clinical training with scent materials (3 months). Primary needs of the animal are taught through repetitive exercises that ensure both short and long term memory acquisition. Additionally, basic obedience is taught, but not at the expense of "scent location at all costs". This training will take place at a dedicated 3200 square foot dog training facility in Shediac, New Brunswick
Matrix training. The scent must be detected in a variety of locations and amid a broad range of other scents. For this reason, the target scent must now be mixed with other scents and detection be positively reinforced repeatedly. This process also allows discrimination training whereby the dog learns to avoid distractions and attractive scents and focus solely on the target scent.
Practical training (2 week). On location training must include various climate conditions and multiple locations.
|Percent success of alerting to clubroot|
|Time to alert to target scent|
We have successfully met all objectives described in the application. Objective 1 was to select appropriate dogs for training. Two successful canines were selected based on age and energy level. Josie was a very athletic 2 year old Belgian Shepherd that had some scent work experience. The second dog (Adi) was a very exuberant 1 year old Golden Doodle that was a rescue animal, and a novice with respect to scent detection.
Objective 2 was to clinically train the animals to recognize the scent of clubroot galls, and alert the trainers to its presence. This was successfully done at Grimmer's Canine College in Shediac, NB. Adi was trained to dig and paw at the target scent and Josie was trained to bark at target scent detection. The third objective was to perform scent matrix training where training was done in multiple environments and/or with many distractions and distractor scents. This was successfully performed at Grimmer's Canine College in Shediac, NB.
The final objective was field training to confirm the dogs ability to detect clubroot on canola in multiple locations and soils. The field training was successfully performed in Alberta (County of Newell ≥ 2 fields, and Leduc County ≥ 2 fields). In September of 2019, the dogs and trainers visited Alberta and training in canola fields was done.
Searching for target scent (in a canister) was successful in the first two fields. Detection of excavated galls was successful in the second field. Detection of in situ galls was successful in the final two fields. The dogs were successful at detection of clubroot galls in dry brown soil, wet black soil, and dry black soil. Detection of galls in wet brown soil and in grey wooded soil was successfully done in a clinical setting.
|Fig 1. Percent success of alerting to clubroot for two canines|
|Fig 2. Time to alert to target scent for two clubroot detector canines in various scenarios|
|Fig 3. Canine detecting clubroot in canola stubble.|
|Use clubroot resistant cultivars|
|No host crop for at least 2 years (prevent/maintain)|
|Sanitize equipment to prevent spread|
|No host crop for more than 2 years if disease pressure is high|