THE SPREAD OF PLANT DISEASES. 117 



MEETING FOE LECTURE AND DISCUSSIOK 



Saturday, March 27, 1897. 



A meeting for Lecture and Discussion was liolclen today at 

 eleven o'clock, the President, Francis H. Appleton, in the 

 chair. 



The following lecture was delivered on the John Lewis Russell 

 Foundation : 



The Spread of Plaxt Diseases — A Consideration of 

 Some of the Ways in which Parasitic Organisms are 

 Disseminated. 



By Dr. Erwik F. Smith, Assistant Pathologist, Division of Vegetable Physiology and 

 Pathology, United States Department of Agriculture, Washington, D.C. 



The subject selected for this address is a rather large one for 

 treatment in a single lecture. Parasitic diseases of plants are 

 disseminated in a great variety of ways. I shall not try to 

 cover the whole field. All I desire or expect to do at this time 

 is to call yonr attention in a plain, straightforward way to cer- 

 tain well-known facts, and to others not so well known, drawing 

 as I proceed certain inferences or conclusions which may be of 

 use to you hereafter in your daily work. This lecture will neces- 

 sarily be rather categorical, and not of much interest, I fear, 

 except to those who are actually growing plants as a means of 

 livelihood. I shall for the most part neglect the common and 

 well-known dissemination of parasites by wind and water, and 

 deal chiefly with methods of dissemination which are to a large 

 extent within our control. " The wind bloweth where it listeth," 

 and we cannot stop it, but there are certain dangers we may 

 avoid, and some of these I will endeavor to point out. I wish 

 particularly to show how farmers, fruit growers, florists, market 

 gardeners, and all who have to do with the growing of plants are 

 themselves not infrequently responsible for the spread of dis- 

 eases, which either destroy their crops outright or leave the bal- 

 ance on the wrong side of the ledger. If I can make this one 

 fact perfectly clear to you, your own reading and reflection will 

 do the rest, and I shall not have cast ray seed into stony places 

 or by the wayside. 



As you all know, our modern intensive cultivation of flowers, 

 fruits, and vegetables for market purposes is beset with many 



