Murphy, Paul Aloysius (1887–1938), plant pathologist, was born 22 February 1887 at Ballybur, Cuffesgrange, Co. Kilkenny, son of James Murphy, farmer, and Julia Murphy (née Mackey). He attended St Kieran's College, Kilkenny, before attending the Albert Agricultural College, Glasnevin, Dublin (1906–7) and the Royal College of Science, Dublin where he obtained his diploma (1910) and degree (BA, 1913). He acted as temporary assistant (1911–13) to George H. Pethybridge, director of the seed testing station and plant disease division of the Department of Agriculture and Technical Instruction (DATI), and began working in plant pathology, particularly on the potato blight fungus, Phytophthora, at the Clifden summer field station, Co. Galway. His first paper with Pethybridge, ‘A bacterial disease of the potato plant in Ireland’, was published in the Proceedings of the Royal Irish Academy (1911). Two years later he described for the first time the production of spores of the potato blight fungus under laboratory conditions (Scientific Proceedings of the RDS, 1913). In recognition of his work he was awarded a development commission scholarship and travelled to study at the Imperial College of Science and Technology, London, and the Biologische Reichsanstalt, in Berlin-Dahlem. Leaving Germany in 1914 and being rejected on health grounds for military service, he completed his scholarship at Cornell University, USA. After this he accepted a post as the first officer in charge (1915–20) of the newly established plant pathology laboratory, Prince Edward Island, Canada. There he developed a programme for the investigation of plant diseases and headed the newly-formed seed potato inspection service founded (1914) by H. T. Gussow for Prince Edward Island and Nova Scotia. He developed a particular interest in the potato mosaic virus, and was the first to point out the extent of potato losses caused by this virus (1917). Through his researches he elucidated the complex nature of the disease, and showed that it was, in fact, a series of diseases due to distinct viruses. He also began investigating the role of viruses in the ‘degeneration’ of potato stocks whereby, over a number of years, vegetatively propogated potato plants lost their vigour and original cropping power.
Returning to Ireland in 1920, he continued similar work with the Department of Agriculture and Technical Instruction. After Pethybridge moved to England (1923) to become chief plant pathologist to the Ministry of Agriculture, Murphy became director of the plant disease division of the DATI, the seed-testing section passing to H. A. Lafferty. In 1926 the University Education (Agriculture and Dairy Science) Act became law, and on 1 October that same year the Albert Agricultural College, Glasnevin, comprising 150 acres of buildings and farms, passed to UCD and Murphy was appointed to the newly created chair of plant pathology. He developed an active research school and, with his colleagues, continued the work on potato viral diseases as well as investigating a wide number of plant pathogens including onion mildew, swede dry rot, sugar-beet crown rot, and American gooseberry mildew.
The degeneration of potato varieties in Ireland and elsewhere had been a particular problem for growers for many years. Murphy and his co-workers established that several different identifiable viruses were causing the problem. A method of producing virus-free stocks of pure potato varieties was developed and resulted in the establishment of the Irish potato-seed certification programme. Ireland was the first country to do this and Irish-certified seed potatoes gained an international reputation. The technique became standard practice for potato production worldwide. In 1927 Murphy discovered for the first time the resting spores of the potato blight fungus in nature, a development from his earlier work in 1913. As a consequence of his work in potato husbandry the college received an endowment from the potato marketing board, through which it was able to construct laboratory buildings at Glasnevin and fund the salaries of research assistants.
In recognition of his contribution to plant pathology Murphy was awarded several honours during his life: Sc.D. (NUI, 1922), the John Snell memorial medal (1927) by the National Institute of Agricultural Botany, and the RDS Boyle medal (1932). He was a member of the RDS (where he was a committee member), the Phytopathological Society of America, and the Agricultural Research Council's committee on virus diseases in plants. At the time of his death he had contributed over fifty papers to national and international journals. A list of his papers up to 1932 is found in Proceedings of the RDS, xx, no. 37 (1930–33), 548–9. Murphy's rigorous and detailed work also contributed to the establishment of several new principles of virus biology, particularly on the nature and transmission of viruses, as well as on the practical applications to agriculture.
An extremely hard worker, he was a pioneer in his field, but is also remembered as a stern man and a stickler for timekeeping. He is known to have stood with his watch noting arrival times of students. He was married and had two sons, one of whom worked as a zoologist in the department of agriculture, Nottingham University. After an illness of a few months he died 27 September 1938 at the early age of 51 in a nursing home in Dublin. Robert McKay (qv), his colleague, succeeded him as professor of plant pathology.
In 1979 the Albert Agricultural College closed and in 1980 the National Institute of Higher Education, Dublin, latterly Dublin City University, opened on the same site, the Albert College Building being the only significant building remaining.