In 1920, as a result of her research into grain rusts while completing her undergraduate and master's degrees at Macdonald College, she was offered a research position at the
University of Saskatchewan in
Saskatoon. She accepted, and from 1922 to 1925 was on
faculty as an
assistant professor in the Department of Biology, joining her former advisor W.P. Fraser, among which duties was included teaching. During this time, she conducted her doctoral studies at the
University of Minnesota, where under the supervision of
Elvin C. Stakman she was the first woman in Canada to complete her
Doctor of Philosophy (Ph.D.) in agricultural science in 1922 with the dissertation
Studies in wheat stem rust (Puccinia graminis tritici). Stakman had also been researching stem rust. She did this by spending six months in Minnesota, then six months in Saskatoon. In 1925, she was invited by
William Richard Motherwell, the federal
Minister of Agriculture, to help manage the newly opened
Dominion Rust Research Laboratory at the
University of Manitoba in
Winnipeg, established as a response to rust outbreaks in 1916, 1919, and 1921. She was appointed the laboratory's senior plant pathologist, a position she maintained until retirement, and brought with her former student Thorvaldur Johnson as her research assistant. She established an annual stem rust survey in Western Canada, discovering a diversity of
races in rust populations, which eventually enabled her to discover and catalogue the wheat species and cross-species resistant to stem rust. She published 45 scientific papers on stem rust fungi and 11 research summaries. In 1929, she became a
charter member of the Canadian Phytopathological Society and became one of the editors for the journal
Phytopathology. Newton identified physiologically distinct races of
Puccinia graminis and focused on determining their genetic structure, physiology, origin, and life cycle. She investigated
stripe rust on wheat and
barley and
wheat leaf rust, and the environmental factors on disease expression in wheat plants. She also researched the genetic structure of wheat rust pathogens. The research attracted global attention, particularly from scientists in grain-growing nations dealing with productivity losses from stem rust. She was by this time internationally regarded as an authority on plant rusts, and represented Canada at scientific conventions in the
United States,
Europe, and
Russia. Her research was economically significant, as it was used to develop rust-resistant wheat
cultivars and resulted in a "reduction of annual losses of wheat due to rust from 30 million bushels to practically none". Wheat rust is no longer a significant problem in Canada. In 1933 the
Government of the Soviet Union, worried about persistent crop losses caused by stem rust, invited Newton to
Leningrad at the behest of
Nikolai Vavilov to "train fifty carefully selected students in the problems of rust research". She was there for three months, during which she enjoyed a privileged status similar to a Russian official, and was shown every phase of plant research conducted at the
Lenin Academy of Agricultural Sciences. Vavilov had attempted to lure her to work in Leningrad in 1930 by offering a generous salary, technical support, and a camel caravan for travel. ==Retirement==