Anton de Bary – the Father of Plant Pathology

Yesterday was the birthday of Heinrich Anton De Bary (1831-1888) – the founding father of plant pathology (the study of plant diseases). De Bary was a model scientist: an inspiring teacher – gifted with intelligence, thoroughness and vision. His extensive studies of fungi and cyanobacteria were landmarks of biology. He was the first to unambiguously demonstrate that microorganisms were the cause and not the consequence of plant diseases.

A botanist’s heart in a physician’s body

Anton De Bary was born 184 years ago, on January 26th, 1831 in Frankfurt/Main, Germany. His oddly French name originates from his Waloon ancestors, who had left Belgium in the latter part the 17th century for religious reasons. Anton’s father was a well-to do physician with a strong interest in plants. In those days physicians were often botanists, because the depended heavily on herbs to treat diseases. The elder De Bary had leased an island in the river Main where he set up his private botanical garden. Here, he taught his son what he knew about botany and encouraged him to join the excursions of naturalists associated with the Senckenberg Institute, who collected specimens in the nearby countryside. Encouraged by his father, Anton de Bary went to medical school in Berlin and received his medical doctorate Dr. med in March 1853, at the age of 22, although his dissertation title was a botanic subject “De plantarum generatione sexuali”.

Two days before he received his medical doctorate, De Bary published a book on the fungi that cause rust and smut disease in plants. Quickly, his interest for botany overrode the medical one. He liked to tell that diseases only interested him, until the diagnosis was sure, so after just two month – in the interest of the sick as he added jokingly – he gave up the medical profession and became Privatdozent for Botany at the medical faculty of the University of Tubingen in December 1853.

Two years later – not yet 25 years old – he accepted a position at the small university of Freiburg, where he married Antoine Einert, with whom he had four children. After a five-year stopover in Halle, de Bary succeeded the position of Professor Diederich Franz Leonhard von Schlechtendal at the University of Halle in 1867. As editor of the botanical journal Botanische Zeitung, he exercised great influence upon the development of botany. Finally in 1872, he became a professor for botany at the newly founded University of Strasbourg.

What causes plant diseases? De Bary’s work on wheat rust and potato blight.

Drawing of the potato blight pathogen in Die gegenwärtig herrschende Kartoffelkrankheit, ihre Ursache und ihre Verhütung (1861).

Drawing of the potato blight pathogen in Die gegenwärtig herrschende Kartoffelkrankheit, ihre Ursache und ihre Verhütung (1861).

De Bary’s major scientiftic achievement was that “he brought clarity to the study of fungi and fungal diseases in plants,”1. At his time, the origin of plant diseases was not known. A lot of crude theories lingered around: Microbes were considered to arise spontaneously on diseased or dead plant tissue and plant diseases were believed to be caused by either “the little people”, the devil (to mock people), God (to punish people), static electricity in the air or the weather (Since people became sick when the weather became cold and wet, why wouldn’t potato plants become sick?).

De Bary dismantled a lot of this shoddy science. First, he demonstrated that the spores of Puccinia graminis – the causal agent of wheat rust – were formed from fungal mycelium and not by spontaneous generation. Later, he combined thorough experimentation with microscopic observation to unravel the complicated life cycle of the wheat rust fungus. You may recall from the MEMF article on wheat rust that rust fungi produce not only one type of spores, but five different ones. Some of these spores are not able to cause infection of wheat. De Bary took into account the presence of an alternative host – the barberry plant – and carefully tested which spores could infect which plant by inoculating wheat and barberry plants with the uredospores, teliospores, basidiospores, spermatia and aeciospores.

During De Bary’s childhood, the potato blight disease – that caused the Irish potato famine – occurred in Germany too, but not so destructively. Following his work on the rust life cycle, De Bary in 1860 turned his attention to the potato blight pathogen. Again, he connected the dots of valid preexisting ideas by careful experimentation. He was the first to observe the swimming spores of Phytophthora emerge from their sporangia and penetrate leaves. Soon, he succeeded in infecting healthy potato plants with sporangia taken from diseased leaves. 15 years earlier, Reverend Miles Berkeley had published the revolutionary insight that the potato blight disease was “the consequence of the presence of the mould, and not the mould of the decay…”, but while his work was based on observation, De Bary demonstrated experimentally cause and effect.

De Bary laid the foundation for the study of plant diseases worldwide

Anton de Bary surrounded by students in Strassburg (before 1888).

The scope of De Bary’s work is astonishing. His textbook “Morphologie und Physiologie der Pilze”, published in 1866, marked the beginning of the modern study of fungi. Besides his work on fungal life cycles, De Bary asserted that blue-green algae were bacteria (they are known as cyanobacteria today), demonstrated that yeast are fungi, and coined the term “symbiosis” for “the living together of unlike organisms”. As a teacher, he encouraged his students to exact observation and independent, critical thinking – especially of themselves. “You can’t avoid mistakes during the observation, but you have to know them”, he said. Instead of giving his students a formulated topic, he gave them an object and let them find the study question themselves, because “the right question is already half the work”. He attracted and inspired scientist from all over the world and through his former students (Mikhail Woronin from Russia, William Farlow and Marshall Ward from the US and Schimoyama from Japan) established the study of plant diseases in the many countries.

De Bary died of a tumor of the jaw on January 19, 1888 in Strasburg.



James G. Horsfall 7 Stephen Wilhelm, Heinrich Anton de Bary: Nach einhundertfuenfizg Jahren, Ann. Rev. Phytopathol., 1982

Ludwig Jost, Zum hundersten Geburtstag Anton de Barys. Lebenswerk eines Botanikers des 19. Jahrhunderts. Jena. Verlag von Gustav Fischer, 1930

1 Nicholas P. Money. The Triumph of the Fungi. A rotten history. Oxford University Press. 2006


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