Building on the work of
Sir Alfred Daniel Hall, Cayley started investigating the phenomenon of "Tulip Breaking" – the formation of feather-like patterns on tulip petals. Through bulb-grafting experiments, she found that "Tulip Breaking" could be transferred from one plant to another, rather than being genetic in nature. She concluded that the infectious agent was a virus as the filtrate of an infected bulb did not cause "breaking", and that the virus was probably spread by aphids. Cayley described her findings in two articles published in 1928 and 1932. Cayley was also interested in other microbes. She worked on the diseases of peas and fruit, including the life history of the fungus that caused
apple ‘die-back’. She studied the growth and development of
slime moulds. She improved understanding of sexual reproduction in the
fungi. She also investigated
mushroom compost. == Career roles and service ==