66 HISTORY OF PHYTOPATHOLOGY 



The discovery and establishment of the causal relation 

 of bacteria to plant diseases, made during the first years 

 of this period, was in many ways of even greater signifi- 

 cance and importance than the discovery of the fungi- 

 cidal value of copper. It is the greatest contribution to 

 phytopathologic etiology since the epoch-making dis- 

 coveries of de Bary and his contemporaries on the causal 

 relation of fungi to plant diseases. The credit for this 

 great discovery belongs to an American, Thomas J. 

 Burrill. In justice to our European colleagues it must 

 be recorded that working only a little later and inde- 

 pendently a Dutch plant pathologist, J. H. Wakker, 

 made a similar discovery (see footnote 2, page 61). Bur- 

 rill, however, published his discovery first. 



Thomas Jonathan Burrill, born in 1839 in Massa- 

 chusetts, was educated at Illinois State Normal School. 

 He held the honorary degree of Ph.D. from Chicago 

 University (1881) and later the LL.D. from the North- 

 western University. For many years he filled the chair 

 of botany at the University of Illinois, and from 1879 

 until his retirement in 1913 was Vice-President of the 

 University. He died in 1916. The discovery of the 

 bacterial nature of the fire blight of pears and apples is 

 but one. though unquestionably the greatest, of his 

 several contributions to American botany and plant 

 pathology. The details of his observations and experi- 

 ments on the cause of fire blight are to be found largely 

 in the papers he presented and the discussions in which 

 he engaged before the Illinois Horticultural Society during 

 the years from 1878-84 (see footnote 1, page 61). The 

 reports of this society for these years will repay perusal. 

 Of such great importance is this disease that following 



