THE SCIENCE OF PLANT PATHOLOGY.* 



BY PROFESSOR FRANK LINCOLN STEVENS, PH.D.. 

 North Carolina College of Agriculture. 



From the time men first had interest in plants, knowledge 

 of their imperfections or premature death has existed, with- 

 out, however, definite conception that the imperfections in 

 question really constitute a condition of disease. 



The Bible and the early writings of the Greeks and Romans 

 contain references to what we now recognize as wheat rust, 

 fig blight, insect galls and other of the more strikingly con- 

 spicuous plant ailments. Such references are more abundant 

 in the literature of the seventeenth century, and in the latter 

 part of that and the eighteenth century a few papers giving 

 careful descriptions of malformations due to insect invasion 

 appeared. Even the law was invoked to aid in combating 

 the wheat rust in France as early as 1660. Prior to the nine- 

 teenth century, however, knowledge of plant diseases can 

 hardly be said to consist of more than mere observation of the 

 fact tha f such diseases occur, and the little real knowledge 

 that did exist was swamped by rampant superstition. 



It is natural that the first attempts to explain imperfections 

 were founded upon climatic and soil relations. Vestigial 

 beliefs prevail to this day throughout the country among the 

 untutored to the effect that the various blights, rusts, rots, 

 mildews, etc., are caused solely by untoward conditions of 

 weather, or the unpropitious position of celestial bodies or 

 some other occult influence. 



The significance of one great factor in the production of 

 plant disease, namely the parasitic fungi, remained quite 

 unrecognized until the second decade of the nineteenth cen- 



* Reprinted from The Popular Science Monthly, September, 1905. 



1905] 61 



