PHYLLOSTICITA 



411 



Apple blotch. Scott and Rorer have quite recently de- 

 scribed a serious disease attacking apples in the United 

 States. The injury is caused by Phyllostida solitaria (Ellis 

 and Everh.). The fungus forms cankers on the young shoots ; 

 irregular, light brown, yellowish, or whitish, quite small 

 patches on the leaves ; and blackish, irregular patches on the 

 fruit, the surface of which often cracks in consequence. 

 Minute black perithecia are produced in abundance on 

 diseased spots, both on twigs, leaves, and fruit. The first 

 spring infection is due to spores produced on infected twigs. 



Fig. 128. Phyllosticta prunicola. 1, apple leaves attacked 

 by fungus ; 2, section through a perithecium embedded in 

 the substance of the leaf; 3, conidia. Figs. 2 and 3 mag. 



Perithecia minute, immersed in the matrix, the mouth 

 alone rupturing the epidermis, appearing as minute raised 

 points ; conidia hyaline, broadly elliptical, continuous, sur- 

 rounded by a mucilaginous sheath which runs out at one end 

 of the conidium as a hyaline appendage, which is apt to be 

 overlooked, 8-ioX 5-6 /;.. 



I have repeatedly met with perithecia containing conidia 

 precisely similar to those described above, during the spring 

 months, growing from the stroma-like portion of Venturia 



