116 James G. Horsfall 



OTHER DISEASES 



Professor F. C. Stewart of the New York State Agricultural Experiment 

 Station at Geneva, New York, gave the writer a note regarding Rosen's 

 (1924) bacterial disease of foxtail, which he had found near Geneva in 1919. 

 He sent material to Rosen, who confirmed the diagnosis but remarked 

 that the spots are different from those usually found in Arkansas in being 

 larger and more regular in outline and somewhat more conspicuous in 

 color. The head smut of Setaria caused by Ustilago neglecta Niessl. is 

 common. 



The discussion of diseases of other grasses found incidentally in meadows 

 would occupy too much space in this paper in proportion to their im- 

 portance. Miss Sampson (Stapledon and others, 1922) has discussed the 

 diseases of miscellaneous grasses to a limited degree as they occur in Wales. 

 Although the writer has been unable to obtain the publication in the Cornell 

 library, there appears to be an extensive discussion of grass diseases by 

 Bunting (1928) as they occur in the Gold Coast of Africa. 



DISCUSSION AND SUMMARY 



This investigation was undertaken because of the lack of easily accessible 

 information concerning diseases of meadow crops in the State, crops which 

 have a greater total valuation than that of any other single crop in the 

 State. 



The chief contributions of this paper are: (1) the development of a 

 relatively simple technic for estimating loss in the field from leaf spots of 

 meadow crops; (2) estimates of losses induced by these leaf spots in New 

 York in 1928; (3) the symptomatological characterization of the various 

 diseases; (4) a review of the nomenclatorial tangles to determine the most 

 logical name for certain of the pathogenes; (5) observations and experiments 

 upon life histories; and (6) provisional determination of the possibilities 

 for field control of the diseases by dusting. 



When an investigator sets himself to work on the diseases of a crop, he 

 is confronted immediately with the desirability of knowing which are the 

 most important diseases and what the losses are that are caused by each. 

 To ascertain the losses from stem and foliage diseases is difficult but is of 

 peculiar significance where the foliage is the most valuable portion of the 

 plant, as is the case with most meadow crops. The method for determining 

 losses presented herein, and which is based upon an " index of infection " 

 procured from a careful survey of almost 200 fields in the State, gives some 

 measure of the absolute loss in addition to rating the diseases according to 

 their relative economic importance. The method, however, probably 

 gives too conservative an estimate of destructiveness because it does not 

 measure the subsequent effects which defoliation produces. With this 

 method, however, a measure of loss in individual fields based upon the 

 percentage of diseased leaves may be obtained. 



