The most important advance in prophylactic procedure came with the introduction of the Bordeaux mixture, a compound of lime, bluestone and water, by Millardet in 3885. Since that date the battle has waged fiercely with successive conquests for plant pathology. Now many of the most important diseases are well understood and many successful modes of treatment have been devised.
Some of these with their most significant dates are represented in Table I.
During the seventies there were only two or three investigators in plant pathology in America. This number rapidly increased until between 1888 and 1900 over 4,000 papers upon this subject appeared. Only a few dozen economic plant diseases had been even cursorily described prior to 1880, while to-day a total of over 500, more than 250 of them serious, have been investigated. Countless diseases of wild plants also are now known more or less completely.
To enable comparison of the real advance made in plant pathology with the advances made in the sister fields of veterinary medicine and human medicine, two tables are given summarizing the history of these two fields as regards a few of the most important diseases (tables 11. and III.).
That plant pathology has made such a relatively good showing notwithstanding her tardy start is due to the late influence of the germ theory of disease in all of these fields.
With the continual increase of plant diseases in both number and aggressiveness every effort of the plant pathologist will be required to increase the efficiency of treatment. So also is there great need of a public opinion favoring rational plant sanitation. The chief diseases now prevalent as well as those which are liable to invade any section in the near future should be known to all plant producers. Especially needed are laws properly enforced to restrict the migration of diseases.