While 40-metre booms are becoming more popular in Canada, they do create challenges as Canadian spray application expert Tom Wolf told delegates at the GRDC Updates
While Canadian grain growers have moved to the wholesale adoption of self-propelled spray units to combat weeds, pests and disease, spray drones are also emerging as a new technology in their arsenal.
In a presentation to the GRDC Grains Research Update – Perth in February 2025, Canadian spray application expert Tom Wolf provided an overview of spray application trends in western Canada.
Mr Wolf, from Agrimetrix Research & Training, Saskatoon, also spoke at other GRDC Updates across Australia.
He told the audience that self-propelled sprayers had fully replaced pull-type sprayers
in western Canada.
The best sellers were 6000-litre tanks, with the most common boom width 36 metres, although 40m booms were becoming more popular and two manufacturers were offering 48m units.
Spray unit challenges
The larger units do come with challenges, however. They can weigh up to 18 tonnes while empty, so need larger tyres to reduce compaction, which increases the amount of crop trampling.
A lack of boom stability and operation at heights of up to 90 centimetres and speeds of 25 to 30 kilometres per hour have also reduced the uniformity of chemical deposits and increased drift.
“We have not been able to document trends in drift complaints,” Mr Wolf said.
“But our research studies suggest that for a given spray quality, airborne spray drift has increased about twofold for a high-clearance sprayer travelling at 25km/h at a 90cm boom height.” This was compared with one travelling at 13km/h with a 60cm boom height, he said. “The increase in drift is attributed to the combined effects of boom height and travel speed, creating a trailing plume of drift that contains a larger proportion of the applied volume.”
Lower the boom
Mitigating strategies were to lower the boom and slow down. This could be enabled by improvements in logistics that allowed tanks to be filled more quickly, which created additional time for slower applications, he said.
“The alternative, to use a coarser spray, while also effective, will challenge coverage, particularly since the use of contact modes of action has become more important in the age of herbicide resistance.”
He said there was also plenty of room to improve boom stability, with European-made sprayers providing superior boom performance and spray tank plumbing than domestic models.
“Unacceptable boom sway and yaw remain as one of the inexplicable laggards in sprayer design,” Mr Wolf said.
Optical spot sprayers have not been adopted in Canada to the extent they have in Australia, primarily because of the reduced window for green-on-brown application in the pre-seed system.
Drone applications
There is growing interest in the use of spray drones. At a cost of about A$41,000, these are relatively cheap compared with spray units.
However, Mr Wolf said Canada’s Pest Management Regulatory Agency had determined that drones represented a significantly new pesticide application method and required a full and new risk assessment prior to labelling.
Currently, only four pest control products are registered for drone applications – none of them for agricultural use. Recent studies have highlighted significant challenges. These are related to the evenness of spray coverage and the ability to maintain effective swath width, with slight changes to wind speed and flight direction significantly impacting coverage.
More information:
