124 



MORTIER F. BARRUS 



The relation of growth of this fungus to acid and alkaline media has 

 not been studied by the writer, though he has observed that not as 

 good growth is secured when the fungus is cultured in a potato-agar 

 medium made acid by the addition of one drop of 50-per-cent lactic acid 

 to 10 cubic centimeters of medium, as when such acid is not added. 

 Edgerton (1910:28) records a fair growth of Colletotrichum lindemuthianum 

 at —16 Fuller's scale, excellent growth at +5, and only slight growth 

 at +20. Glomerella gossypii (South.) Edg. grew better than did Colleto- 

 trichum lindemuthianum in the more acid media. 



The ascogenous stage 



The ascogenous stage of many anthracnoses has already been found in 

 nature or produced in culture. Klebahn (1905) has shown that the 

 Gloeosporium causing sycamore anthracnose is a Gnomonia. He also 

 (1907:65) found the perfect stage of Gloeosporium ribes (Lib.) M. & D., 

 causing an anthracnose of currant leaves, to be a Pseudopeziza. Burk- 

 holder (1917:164) discovered the perfect stage of Gloeosporium venetum 

 Speg. on raspberries to be a Plectodiscella, which he named P. veneta 

 Burkholder. Genera representing perfect stages of other Gloeosporia that 

 have been reported (Stevens, 1913) are Glomerella, Gnomoniella, Gno- 

 monia, Trochila, Physalospora, and Calospora. Most of the anthracnose 

 fungi parasitic on fruits and herbaceous plants, including the one on bean, 

 belong to what is known as the Glomerella type, that is, their perfect 

 stage when found is of the type of the genus Glomerella. Even in their 

 imperfect stage they differ somewhat from the other forms. Edgerton 

 (1908:384) has pointed out the following important differences, among 

 others of minor importance: 



Glomerella type 



Gnomonia and Pseudopeziza types 



Spores oozing out as a pink mass 

 Appressoria produced in certain cultures under 



certain conditions 

 Mycelium in culture varying but little in 



diameter 



Spore mass white, cream-colored, or yellow 

 No appressoria observed 



Mycelium in culture varying in diameter 

 (at least in Gnomonia type) 



