Clara Henriette Hasse (1880–1926)

Clara Henriette Hasse was an American botanist whose research focused on plant pathology. Her paper "Pseudomonas citri, the cause of Citrus canker", published in the Journal of Agricultural Research in 1915, was the first to identify the cause of citrus canker and led to the development of methods for controlling the disease which saved the citrus crops in Florida, Alabama, Texas and Mississippi from being wiped out.

After graduating from the University of Michigan in 1903, she went to Washington, D.C. to take up an appointment as assistant horticulturist and botanist in the Bureau of Plant Industry at the U.S. Department of Agriculture under Erwin Frink Smith, the USDA's pathologist-in-charge. Hasse was one of the twenty assistants that Smith hired during his tenure at the USDA. She later worked at the Florida Agricultural Experiment Station. Hasse died at her home in Muskegon, Michigan, aged 46.