A Study of Meadow-Crop Diseases in New York 19 



if these could be made to produce mature ascospores, they probably 

 would be those of Pleospora herbarum, as described by Gentner (1918). 

 This fungus has been reported from a large number of herbaceous stems. 

 Ultra-violet irradiation, following the method used by Stevens (1928), 

 however, has not induced the perithecia to mature. The writer has 

 obtained single ascospore cultures of what he takes to be P. herbarum 

 from overwintered red-clover stems two seasons in succession. These gave 

 cultures identical in every respect with those of Macrosporium from lesions 

 on alfalfa leaves, including the production of perithecial primordia and 

 spiny conidia. Neither in morphological characters nor in cultural 

 reactions does this fungus correspond to M. sarcinaeforme as isolated 

 from leaf lesions on red clover. It is probable that the Macrosporium 

 from alfalfa and its possible sexual stage, P. herbarum, occurs on alfalfa 

 and red clover, but that M . sarcinaeforme from red clover is limited to 

 that suscept in nature. 



These observations indicate that Tehon and Daniels (1925) are not 

 justified in including the two pathogenes in the same species, especially 

 if the spiny character of the spore walls is constant. Elliott (1917:467) 

 remarks that " echinulation occurred at all times in all the species studied. 

 In some cases part of the spores from a colony were echinulate while others 

 were smooth." The author has found no evidence of variability in the 

 surface character of the conidia of M. sarcinaeforme from red clover. 

 Inasmuch therefore as M. sarcinaeforme Cav. was not described with 

 spiny spores, it cannot be incorporated as the type species nor even 

 included in the new genus Thyrospora. 



Since the original description undoubtedly refers to a smooth-spored 

 fungus on the leaves of red clover, the name Macrosporium sarcinaeforme 

 Cav. is reserved for that species. The purposes of this paper do not 

 warrant a comprehensive discussion of the systematic position of the 

 alfalfa organism aside from saying that it probably is not identical with 

 the one on red clover. 



Pathogenicity. Malkoff (1902:284) first attempted to show that 

 Macrosporium sarcinaeforme. ( av. was pathogenic by inoculating detached 

 loaves in moist chambers with spores. Characteristic spots appeared in 

 IV( mi five to seven days, but no reisolations are reported. Bain and 

 Kssary three years later (1905:503) say, "The Macrosporium disease 

 appears capable of destroying the clover plant unassisted by any other 

 parasite, though this statement is based only on inspection in the field." 

 Krakover completed Koch's rules of proof for the organism. The fungus 

 has been isolated a number of times by this author and has been grown in 

 pure culture. It was then inoculated onto healthy red-clover plants. 

 The typical spots were produced, and the fungus was reisolated, giving 

 cultures indistinguishable from the original. Spores from these reisola- 

 tions again produced the disease when inoculated onto other red-clover 



