John Hubert Craigie

John Hubert Craigie, plant pathologist (b at Merigomish, NS 8 Dec 1887; d at Ottawa, 26 Feb 1989). Craigie discovered the sexual process in rust diseases of wheat. After military service (1914-20), Craigie joined the Dominion Rust Research Laboratory at Winnipeg in 1925 as its specialist in plant diseases. The laboratory was created that year to apply science to crop epidemics that threatened the whole prairie economy, based as it was on Marquis wheat. Earlier scientists assumed that wheat rust (named for its visible red spores) was a single disease that could be controlled by a single chemical or by breeding a naturally rust-resistant wheat. By 1916 it was discovered that rust comprised a whole family of diseases which affected different wheat varieties differently.

In 1927 Craigie made a fundamental discovery, that the rust organism reproduced sexually. It could hybridize - and thus produce new strains of the disease - every season. This breakthrough provided the intellectual basis for research that continues to this day. Wheat crops have to be monitored constantly to detect new strains of rust as early as possible, and the task of breeding new wheats that resist new rusts is never ending (see C.H. GOULDEN).

Craigie received many honours and awards for his discovery, notably fellowship in the Royal Society of London. He was director of the Rust Laboratory 1928-45 and subsequently Dominion botanist.