John Malcolm Hirst had a brother who was about five years older. Their father, who was elected a Fellow of the
Royal Geographical Society, died in 1928, thus causing a financial struggle for his widow and their two sons. Both of the sons were educated at
Solihull School. In 1944 he took command of a motor launch, giving assistance off the coast of Yugoslavia to partisan forces. for aerobiological research. Hirst thought of a new, more efficient method of aerobiological sampling, which he incorporated into what is now called the "Hirst spore trap". His design was presented to Casella Ltd in 1953 for commercial production. Hirst continually improve his design. Later, Burkard Ltd commercially produced a widely used, more advanced trap using Hirst's improvements. In 1955
Imperial College London awarded Hirst a Ph.D. for his studies on forecasting
potato blight. Hirst's research demonstrated the value of a detailed knowledge of spore dispersal in evaluating control procedures for plant diseases caused by fungi. In 1967 he was appointed head, as successor to Philip Gregory, of Rothamsted's plant pathology department. He continued to do research on the phytopathology of potatoes and cereal crops and also developed an interest in methods and systems of farming. In 1975 he left Rothamsted to become the director of
Long Ashton Research Station. His task as director was to convert the research station from an institute focused on horticulture and beverages to an institute devoted mainly to arable agriculture. He retired as director in 1984. At the University of Reading, J. M. Hirst met Barbara Mary Stokes, whom he married in 1957. She earned a B.Sc. in horticulture, and later an M.Sc. while working at Rothamsted Experimental Station. Upon his death in 1997 he was survived by his widow, their two daughters, and three grandchildren. ==Awards and honours==