Two years after Koch and Pasteur (in France) showed that the animal disease, anthrax, was caused by a bacterium, Jonathan Burrill (in Illinois) showed that fire blight disease of apple and pear was also caused by a bacterium.
Burrill began to study fire blight in 1873 and presented a paper on the disease in September of 1876. In this paper Burrill wrote that he had observed "oscillating corpuscles" in the diseased tissue when viewed under a microscope. He did not identify these things as bacteria.
Burrill's second paper on fire blight was presented in December of 1877, he again reported that the "cambium of the blighted branch...is filled with very minute moving particles, very similar to those known as Spermatia in fungi."
Burrill's third paper identified the "oscillating corpuscles" as " moving atoms known in a general way a bacteria". Burrill had introduced these particles into the bark of a healthy tree and observed that "in many cases" fire blight followed. By 1881 Burrill had described the bacterium, but it would not be named for two years.
