Leendert, there is a description of these tests on page 3 of this link.
https://ufdc.ufl.edu/AA00026053/00001/1j
They describe the plane as a Waco floatplane.
"A Waco plane on floats and equipped with a spinner disk was used for the spruce budworm work at Kabonga, Quebec, which was conducted cooperatively by the Dominion Government and the Province of Quebec."
Not sure as to the model but possibly a UIC with floats or a YKS-6 or YKS-7 which are all very similar.
https://www.si.edu/object/nasm_A19791420000
or
https://www.jetphotos.com/photo/8824537
The supporting struts on the wings look the same to me between the two photos and the wing structures look the same.