Chance rather than aspiration led John Hudson to a career in horticulture. A scholarship to New Mills Grammar School, Derbyshire, aroused his interest in physics but his science teacher advised him there was no future in the subject as “everything will shortly be known”. He left school at 16 to work in a small nursery garden venture begun by his father. Chance intervened with his parents' discovery of a one-year horticulture course at the Midland Agricultural College at Sutton Bonington, near Nottingham.

Hudson achieved his diploma with distinction and a recommendation he should read for a BSc in horticulture. After matriculating, he graduated with an external degree from the University of London. At the outbreak of war in 1939, he was the Horticultural Advisor to Sussex County Council and a Territorial Army sapper in the Royal Engineers.

He went to France with the 44th (Home Counties) Divisional Engineer Regiment RE of the British Expeditionary Force and was subsequently evacuated from Bray Dunes east of Dunkirk in June 1940. As an unconscious demonstration of an unusually fine memory, five years later he wrote a detailed account of the traumatic days he and thousands of others spent on the beach awaiting evacuation by small ships to England.

In the late summer of 1940, the Luftwaffe attacks on RAF fighter airfields and London turned to the main ports and industrial cities, with an increasing proportion of raids made at night. About 10 per cent of the high explosive bombs dropped failed to explode, either because they were fitted with delayed action fuses or because the basic mechanism failed.

After his return from France, Hudson was commissioned, trained in bomb disposal and assigned to a unit in Sheffield, which was severely bombed on December 12 and 15, 1940. The notes he submitted on his early defusing experiences led to him being called to London to join a tri-service team of scientific officers studying delayed action fuses and their antihandling devices. After the United States entered the war in 1941, he accompanied a team of experts to Washington to advise the US services on bomb disposal and in 1943 was appointed MBE (military) for his contribution to this vital work.

He returned to England just as a new type of fuse, fitted with batteries and three mercury switches, was discovered in ten bombs dropped on London. Although the batteries could be rendered flat if cooled by liquid oxygen, the cooling action was liable to crack the case and activate a tumbler device that would detonate the bomb.

Hudson was called to defuse a 500-kilogram bomb fitted with such a fuse near the Albert Bridge. After pouring the liquid oxygen, he withdrew until he heard the case crack. No explosion followed but the fuse could not be pulled clear by the attached line. He climbed down into the trench and twisted the fuse out, describing each move by hand telephone in case of a fatal result.

He was awarded the George Medal for this cool exploit. But he and other experts were soon to face a new threat: the German V1 flying bombs that intelligence sources gave warning should be expected in retaliation for the planned invasion of mainland Europe.

The first salvo of ten V1s was launched on the night of June 12-13, 1944, only seven days after the invasion of Normandy had begun. Two nights later 200 were launched, 144 travelled beyond the coast and 73 fell on Greater London. Hudson was assigned to defuse the warhead of one of the first to land without exploding. He found the bomb had three fuses, of which the third was of yet another new type. The citation for the bar to the George Medal awarded to him for defusing the V1 praised the technical excellence of his work and the observations he recorded under conditions of extreme tension.

John Pilkington Hudson was born in Chapel-en-le Frith, Derbyshire, the only son of the postmaster, Arthur Hudson. He was demobilised at the end of the war in Europe to take up an appointment with the Department of Agriculture in Wellington, New Zealand. (The account of his days on Bray Dunes was written on a train journey from Christchurch to Dunedin). He returned home in 1948, becoming head of the department of horticulture at the University of Nottingham in 1950, Professor of Horticulture in 1958 and Dean of the Faculty of Agriculture and Horticulture in 1965.

His professional career embraced three strands: education, research and the translation of research for the grower. He was seconded to the University of Khartoum from 1961 to 1963 to establish a department of horticulture there. He became the director of Long Ashton Research Station and Professor of Horticultural Science at the University of Bristol in 1967. He was appointed CBE (civil) in 1975 and received the Royal Horticultural Society's Victoria Medal of Honour the following year.

He served on the Joint Advisory Committee on Agricultural Education until 1973 and was the editor of Experimental Agriculture, 1965-82, contributing to a variety of scientific publications on the effects of environment on plant growth and productivity. An infectiously optimistic man, he had a serene temperament, as ideally suited to his chosen profession as it was to his tense wartime work with unexploded bombs.

His wife Gretta, née Heath, whom he married in 1936, and a son predeceased him. He is survived by his younger son, Richard Hudson, Emeritus Professor of Linguistics, University College London.

Professor John Hudson, CBE, MBE (Military), GM and Bar, bomb disposal expert and horticulturalist, was born on July 24, 1910. He died on December 6, 2007, aged 97