viii Minnesota Plant Diseases. 



It is to be regretted that a systematic survey of the plant diseases of the state, 

 sufficiently thoroagh to determine the full extent of the damage due to these diseases, 

 has not been possible. The Minnesota Agricultural Experiment Station has never 

 employed a special plant pathologist, and the records of the station on plant diseases 

 are therefore only fragmentary. The author has, in the pursuit of his studies on the 

 fungi of Minnesota under the Geological and Natural History Survey of the state, be- 

 come more or less acquainted -with many of the plant diseases, and this volume is in 

 part the result of such observations as were made in that work. 



The omission of some diseases is naturally unavoidable, and on the other hand 

 it has been deemed advisable to include many diseases which are doubtfully of much 

 importance in this state. These have been added either because their prevalence is 

 to be expected on account of tfieir existence in neighboring states, or on account of 

 their general importance in other parts of tlie country. While not wishing to bori-ow 

 trouble from the future, it is well to be forewarned. The old adage, "a stitch in time 

 saves nine," is peculiarly appropriate. Again, plant diseases are here described which 

 are economically of minor importance, but which are illustrative of certain impor- 

 tant classes of diseases, and, as it has been pointed out that this work pretends to be 

 chiefly educational, such diseases become, secondarily at least, of considerable im- 

 portance. 



I w^ish to express my thanks to the following for assistance in various ways, as 

 in the use of plates, photographs, material or literature : Mr. F. K. Butters, Profes- 

 sor E. W. D. Holway, Mr. H. Cazaet, Professor F. L. Washburn, Miss D. Hone and 

 Dr. H. L. Lyon of the University of Minnesota ; Mr. C. J. Hibbard of Minneapolis; 

 Dr, Francis Ramaley of the University of Colorado; Professor G. F. Atkinson of 

 Cornell University ; Professor R. S. Macintosh of the Alabama Experiment Station ; 

 Dr. G. P. Clinton of the Connecticut Agricultural College; Professor H. Marshall 

 Ward, F. R. S., of the University of Cambridge; Professor Roland Thaxter of Har- 

 vard University; Professor F. C. Stewart of the New York Experiment Station; Mr. 

 F, J. Seavers of the University of Iowa; Mr. M. A. Carleton of the United States 

 Department of Agriculture ; Professor H. L. Russell of the Wisconsin Agricultural 

 Experiment Station ; Professor B. M, Duggar of the University of Missouri; Mr. S. 

 A. Sirrine of the New York Experiment Station ; Professor J. C. Blair of the Illinois 

 Agricultural Experiment Station; Mr. C. G. Loyd of Cincinnati; Dr. J. C. Arthur of 

 Purdue University; Dr. W. A. Kellerman of Ohio State University; Professor H. L. 

 BoUey of the North Dakota Agricultural College ; Professor B. D. Halsted of Rutgers 

 College; Professor B. O. Longyear formerly of Michigan State Agricultural College; 



