Alberta scientists are studying the hitchhiking habits of clubroot as part of the battle to control one of canola’s worst enemies.
They’ve set up “dust samplers” in the Brooks and Edmonton regions, are checking for clubroot spores in ditches along busy highways, and are using GIS mapping and computer simulations to track the spread of the disease.
“Although we see clubroot mainly in the Edmonton area, I’m understanding that a number of infested fields were found south of Leduc county and in Wetaskiwin county,” said Kelly Turkington, a plant pathologist at the Agriculture Canada research station in Lacombe.
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“So it’s something that is certainly spreading and it’s not confined primarily to the Edmonton region.”
Over the last two years, researchers collected samples from five locations within five fields in a clubroot-infested area north of Edmonton. The cropping histories of the five fields were obtained and researchers are looking for links between those practices and the “resting spore loads” of the clubroot pathogen.
“That may offer practical advice to producers for managing this,” said Turkington, part of a research effort involving the University of Alberta and Ag Canada in Saskatoon.
Soil collected from the five sites was analyzed in Saskatoon to identify variations of clubroot symptoms and disease severity. This analysis helped researchers determine that there is variation in clubroot severity in different areas of the same field.
“There are some significant clusters or gradients within the fields that we’re surveying,” said Turkington. “Conclusions based on whether you have clubroot within a field can be quite significantly affected by where you actually sample.”
Transferred by wind?
The use of computer simulations will help researchers identify regions in Western Canada with conditions conducive to clubroot, he said. One of the questions they want to answer is whether or not the spores which cause clubroot can be picked up by dust particles blown from one field to another.
“The biggest risk is with conventional tillage, where we are tilling the soil and getting some potential for soil erosion via wind,” said Turkington.
Researchers will examine soil samples for the clubroot pathogen and use modelling by soil scientists to see how soil is affected by different cropping practices. They want a better understanding of what soil particle sizes or types the clubroot pathogen might be associated with.
Water erosion potential is also being examined. In 2010, researchers collected soil from ravines, creeks or other areas of run-off in infected fields.
“This is a pathogen that will move with soil particles that are being eroded by either wind or water movement,” said Turkington.
Researchers will also be looking at soil-dispersal potential and will collect soil samples found on roadsides or traffic routes to see how easily clubroot could be dispersed via vehicular traffic. Sampling was done along Highway 2 between Calgary and Edmonton and will eventually be done between Edmonton and Lloydminster.
In 2011, the research effort will start to examine “microgradients” within fields.
“We’re thinking that in a row of canola you’re going to have the highest concentration of resting spores and that concentration will decrease as you get into that inter-row or mid-row space in canola,” said Turkington.
“That could have some implications if you’re looking at controlled traffic farming, wider row spacing or targeted applications of bio-control agents or chemicals to the area in the soil where the resting spore concentration is highest.”
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“Thisisapathogenthatwillmovewithsoilparticlesthatarebeingerodedbyeitherwindorwatermovement.”
KELLY TURKINGTON
PLANT PATHOLOGIST
