A Study of Meadow-Crop Diseases in New York 15 



when associated with affected red clover (Bain and Essary, 1905:503). 

 Elliott (1917:457) reports successful inoculation of white clover and 

 alfalfa with a pure culture of Macrosporium isolated from red clover, 

 but he reports no reisolation of his fungus. Several others also have 

 reported red clover as susceptible to this disease in the field (Milburn and 

 Bessey, 1915:72; Westgate, 1908:42; Centner, 1918; Tehon and Daniels, 

 1925 : 714). Many of these writers undoubtedly have confused this disease 

 with a closely related Macrosporium leaf spot occurring on alfalfa. 



Gentner (1918) declares that Italian red clover is the variety most 

 susceptible to this disease. Hesler (1925:93) found no appreciable differ- 

 ences in the susceptibility of varieties. 



The disease 



Many writers have referred to this disease without giving it a specific 

 designation. Stakman (1922:248), however, called it large leaf spot. 

 Since this spot is not necessarily large, the name Macrosporium leaf spot 

 is proposed to set it off more definitely from other similar leaf spots, 

 especially Pseudopeziza leaf spot with which it is most likely to be confused. 

 Stevens and Hall (1913:390) use the term Macrosporiose to denote the 

 same idea. 



History and range 



Cavara (1890) first discovered this disease near Pavia, Italy, in 1890. 

 It was reported from Germany in 1897 by Tubeuf and Smith (1897:517). 

 Probably the first specimen collected in this country was found on clover 

 by May Varney at Manhattan, Kansas, in 1889 (Tehon and Daniels, 

 1925:714). The disease has been reported from England by Milburn 

 (1915:72). The trouble occurs in the eastern United States from Maine 

 to Louisiana. The first specimen from the vicinity of Ithaca deposited 

 in the Cornell Plant Pathology herbarium was collected in 1915. 



The most recent and complete treatise yet published dealing with this 

 disease is that of Krakover (1917:273-328). 



Symptomatology 



The lesions of this disease are limited almost exclusively to the leaf 

 blades, although they sometimes occur on stems and petioles, where they 

 appear as minute black streaks from 1 to 3 millimeters in length. Pctiolar 

 lesions cause the leaf to yellow prematurely. Milburn (1915:72) says 

 that the disease affects the seeds, which are shrunken and shriveled and 

 much darken- than healthy seeds. In young stages the leaf spots are minute 

 and light brown in color, but they enlarge rapidly, coalesce, and kill the 

 blade when approximately 20 per cent of its urea is affected. The char- 



