Caption

Agnes Quirk (1884-1974), US plant pathologist. In 1901 Quirk joined the United States Department of Agriculture's Bureau of Plant Industry as an assistant to the senior plant pathologist. She became head of one of its main laboratories in 1928, where she oversaw the culturing of bacteria. Quirk studied hydrogen ion concentrations in crown galls and culture media, and the mechanism of begonia plants' immunity to the tumour causing bacterium Agrobacterium tumefaciens, co-authoring a number of papers on the topics.