A STUDY OF MEADOW-CROP DISEASES IN NEW YORK 1 

 James G. Horsfall 



OBJECT OF THE INVESTIGATION 



A paucity of information, especially that which is easily accessible, led 

 to an investigation of meadow-crop diseases. In studying such a wide 

 range of diseases, the writer accumulated an extensive bibliography that 

 has made possible the bringing together of the important information 

 extant on the diseases of meadow crops. No claim to completeness of 

 bibliography is made since many papers, which for various reasons were 

 not found in indices, abstract journals, or other papers, are missing. 



Briefly, the objects of the work have been: (1) to study methods of 

 determining loss from foliage troubles, (2) to describe the diagnostic 

 characters for the diseases, (3) to untangle the nomenclature of the causal 

 organisms, (4) to make observations and experiments upon life history, 

 especially the factors governing spore germination, and (5) to determine 

 the effects of sulfur and copper dusts in combating these diseases. 



The pioneer work of Kightlinger (1925) and the later work of Greaney 

 (1928) and of others in controlling wheat rust successfully with fungicides 

 stimulated the investigation looking toward a similar control for meadow- 

 crop diseases. This study has centered around laboratory tests of the 

 effect of fungicides upon germinating spores, using methods long applied 

 in the laboratory of Plant Pathology at Cornell University and described 

 recently by McCallan (1930). The laboratory tests were supplemented 

 by greenhouse and field studies, although the latter was limited by the 

 facilities available. As McCallan has pointed out, the results of laboratory 

 tests may be used as reliable indicators of the efficiency of fungicides in 

 controlling diseases. Laboratory tests serve admirably to narrow the 

 scope of field work which, of course, will furnish the ultimate criterion of 

 the value of the fungicides. 



The diseases of the three clovers, red clover, Trifolium pratense L., 

 alsike clover, T. hybridum L., and white clover, T. repens L., and of timothy. 



1 Also presented to the Faculty of the Graduate School of Cornell University, February, 1929, as a major 

 thesis in partial fulfillment of the requirements for the degree of doctor of philosophy. 



Author's acknowledgment. The author wishes to express his appreciation for many helpful 

 criticisms and suggestions to Professor H. H. Whetzel, who suggested the problem and under whose im- 

 mediate direction the work was done. He wishes also to acknowledge the assistance rendered by Professor 

 M. F. Barrus and the other members of the staff of the Department of Plant Pathology, Cornell University, 

 who hare rendered assistance of various kinds. 



