DISEASES OF TREES 



INTRODUCTION 

 DEVELOPMENT OF THE STUDY OF VEGETABLE PATHOLOGY 



DURING the present century, and especially during the last 

 few decades, the forests of Germany have been threatened with 

 dangers of a magnitude formerly unknown. These have been 

 occasioned by the gradual relinquishment of natural regener- 

 ation, and by the substitution of pure even-aged woods for 

 woods consisting of trees of different species and of various 

 ages, but most of all by the displacement of broad-leaved trees 

 by pure coniferous woods. It is especially noticeable that 

 enemies from the animal and vegetable kingdoms find favourable 

 conditions for rapid development in our modern forests, so 

 that the complaints of increasing devastation of woods appear 

 to be by no means unfounded. The foresters of the last cen- 

 tury had already made themselves familiar with a large number 

 of the enemies and diseases of trees, as is proved by the 

 appearance in I/95 1 of a work which probably contains the 

 first compilation of the observations on plant-diseases scattered 

 throughout the older literature. We may assume from this that a 

 large number of diseases which have only been properly explained 

 during the last few years, e.g. the damping off of seedling 

 beeches, the resinous degeneration of pine-tops, the red-rot of 

 the spruce, &c., were known to foresters more than a hundred 

 years ago, though of course the explanation of the causes was 



1 Schreger, Erfahrungsmassige Anweisung zur richtigen Kenntniss der 

 Krankheiten der Wald- und Gartenbaume, &c. Leipzig, 1795. 518 pages. 



