By the late 1890's Erwin Smith had identified a number of bacterial pathogens, but he soon learned that plant bacteriology had not gained full acceptance in the scientific community, especially Europe. Alfred Fischer, a Botany professor at the University of Leipzig, published in 1897 a collections of well-respected lectures in which he stated that "no single example is yet known of bacteria which can insinuate themselves into the closed living cells of a plant". In 1898 Smith prepared a reply which was published in 1899 in the presitgious journal Centralblatt fur Bacteriologie with the title "Are there Bacterial Diseases of Plants?". The introduction was "It is seldom in a genuinely scientific book that one finds so many unwarranted assumptions and serious mistatements in the space of a single page." Smith went on to name at least eight bacterial pathogens that were the cause of plant diseases (he had personally worked on 6 of these)--the eight--cucurbit wilt, brown rot of potato, black rot of cabbage, bacteriosis of bean, yellows of hyacinth, pear blight, soft rot of hyacinth, and olive tuberculosis. Smith chastised Fischer for speaking on a subject without being "familiar even with the readily accessible literature in his own language".
Fischer published "The Bacterial Disease of Plants: Answer to Dr. Erwin F. Smith" to argue that his original presentation on bacterial diseases of plants "was completely adequate for a book of the moderate range of my lectures". Fischer also replied that he did not mention Smith's literature because he did not feel it worthy. Fischer felt that the experiments were not rigorous enought to prove indisputably that the bacteria that been found in the diseased plants were the cause of the symptoms rather than a researcher's misinterpretation or contatmination due to poor laboratory technique. Fischer stated that "he was obliged to show why I hold Smith's own work to be unsatisfactory. As long as Smith does not submit to carry out and prepare his experiments satisfactorily with all the necessities of experimental pathology he has no subsequent claim that his work will be evaluated as well guaranteed and certain achievements of science."
Smith's reply was in an article published in Centralblatt entitled "Dr Alfred Fischer in the Role of Pathologist". He rebuted the criticism of Amercian work on fire blight (Fischer had commented negatively against J. C. Arthur's famous fire blight studies) and Smith also questions Fischer's credibility to pass judgement on the work of plant pathologists. "The positive statements of a pathologist who has spent five years industriously studying these special diseases ought to be worth considerably more than the negations of a man who is not a pathologist, and who has not seen a single one of these diseases, much less critically studied one of them."
In 1901, Smith publised the "nail in the coffin" of this debate. He publised a detailed discussion in three parts of his own work, complete with pictures to illustrate his points. He detailed the criteria for proving the pathogenicity of any causal organism. This finally closed the debate.
Information from "The Formative Years of Plant Pathology in the United States" by C. Lee Campbell, Paul D. Peterson, Clay S. Griffith.
