Obituary: Professor J. M. Hirst

J. M. HIRST was the inventor of the "Hirst Spore Trap". The pollen counts broadcast in the media for hay-fever sufferers during our summer months are in large measure a direct legacy of his work.

In 1950, when Hirst joined the staff of Rothamsted Experimental Station in Harpenden, Hertfordshire, the Agricultural Research Council was still much concerned with increasing home food production. His task was to study the spread of potato blight to find better disease control; when or how far spores of the fungus could spread was still conjecture. To monitor spore dispersal he developed a new air sampler. In it a small pump sucked air through a slit to impact spores on to a microscope slide that was moved, by clockwork, slowly past the slit over 24 hours. Microscopic examination of the slide gave a ready picture of the time when spores had been in the air.

It became apparent from the other spores and pollen being caught that there was a distinct and recognisable air-flora. Spores or pollen could be identified by species and their prevalence in the air could be linked to environmental conditions or seasons. The information helped to explain the onset of plant diseases or allergic reactions in susceptible human patients and greatly increased the growing interest in aerobiology. The sampler became known as the "Hirst Spore Trap" and soon was being used to study both the spread of fungal pathogens and the changing airborne concentrations of human allergens. Further modifications have been made to the Hirst trap but its essential nature and use continue to this day.

Jim Hirst was of the generation whose academic careers came to an abrupt halt with the outbreak of war in 1939. He was born in 1921 in a small village near Birmingham. He attended Solihull Grammar School and in 1939 was awarded a Warwickshire County Major Scholarship to go on to university but almost with the award came his mobilisation papers. Hirst's father had died when he was young so the straitened family circumstances meant that holidays were spent with farm worker relatives on the north Norfolk coast. Here he spent nearly as much time with the coastal fishermen as on the farms so that he developed a keen interest both in farming and the sea. For war service he enlisted with the Royal Navy.

He elected to train for Coastal Forces. Part of the training was at Roedean School (which with some foresight had been vacated by its young ladies). Hirst would not often speak of his wartime experiences but occasionally in convivial evening conversation he would lightheartedly introduce "when I was at Roedean".

He joined 31st Motor Launch (ML) Flotilla as a junior officer when it began duties in the Mediterranean. Initially the flotilla was engaged on anti- submarine patrols but then were escorts for landing craft during the invasions of Sicily and mainland Italy. As the Allies advanced the MLs became increasingly engaged in mine-clearance duties, their wooden construction making it easier for them to avoid detonating magnetic mines.

Hirst had a number of commands before being sent early in 1945 to command ML480 in a group given the task of clearing a path to Trieste. To counter the wooden-hulled MLs the magnetic mines were by now fitted with long, floating snag lines attached to their detonators. Except in the calmest water these were difficult to spot and could easily be dragged by propeller or rudder, so clearing such mines was very hazardous.

Early on the first day of the approach to Trieste the lead boat suffered severe damage, and the second boat went to its aid, so ML480 was now the lead. The following day they worked into Trieste, being the first Allied ships to enter. After the war ended Hirst was retained in minesweeping for some months, helping to co-ordinate the clearance of the approaches to the Baltic Sea. His last command was ML155 and in later years his wife, Barbara, was able to buy the ship's bell as a present for him.

In 1946 Hirst entered Reading University to study Agricultural Botany. (It was here he met Barbara.) The 1948 summer vacation he spent as a "voluntary worker" in the Plant Pathology Department at Rothamsted to work with P.H. Gregory, who was beginning his extremely influential work in aerobiology. This vacation was a determining time in Hirst's life, for it was to Rothamsted that he returned in 1950 on gaining a first class degree.

His first published research paper described the new air sampler, the Hirst Spore Trap, and Hirst went on to extend his spore-trapping techniques to other problems, eventually building up a team of associates working on a wide range of diseases. In 1967 he became head of Plant Pathology and in 1970, for his outstanding work in aerobiology, he was elected a Fellow of the Royal Society.

In 1975 Hirst was appointed Director of the Long Ashton Research Station at Bristol. The station had, since its inception as a cider and apple research centre, always been associated with fruit growing. Hirst was charged with re-orientating its research to arable cropping, to match the greatly increased arable area in the west of England. It was not easy for the staff there to absorb the extent of the necessary changes. As orchards, fruit plantations and hedges were grubbed out and cereal crops took their place, it was clear that the end of an era had come. It is a tribute to Hirst's quality of leadership that in his early years as director the transition was achieved successfully.

Then, in the early 1980s, he had to turn his energies to retaining Long Ashton as an Institute, again with success, when several were being closed. As one tribute to Hirst, on his retirement, a new building put up during his time at Long Ashton was named the Hirst Laboratory.

In retirement Jim Hirst gave much time to international agriculture, travelling widely for many organisations. He was a strong-willed, determined but likeable, approachable man.

Alex Bainbridge

John Malcolm Hirst, aerobiologist: born 20 April 1921; DSC 1945; staff, Rothamsted Experimental Station, Harpenden 1950-67, Head of Department of Plant Pathology 1967-75; FRS 1970; Director, Long Ashton Research Station 1975-84; Professor of Agricultural and Horticultural Science, Bristol University 1975-84 (Emeritus); married 1957 Barbara Stokes (two daughters); died Bristol 30 December 1997.