SPHAERIALES 



269 



and germinate in spring, producing conidia of Ramularia Hieracii 

 (Klebahn, 1918). 



Of Cercosphaerella, M. millegrana on leaves of Tilia cordata, forms 

 conidia of Cercospora microsora and, further, the imperfect form of M . 

 cerasella, a leaf spot of cherry, is Cercospora cerasella (Aderhold, 1900). 



As has been indicated, the extent of the imperfect forms of Myco- 

 sphaerella is by no means exhausted in the three sections above; e.g., 

 of the forms important in phytopathology, M. pinodes, causing a spot 

 of pods of beans and peas, has Ascochyta Pisi (Vaughan, 1916) and M . 



Fig. 179. — Sphaerulina intermixta. Its growth forms known as Dematium pullularis. 

 1. Ascus with mature spores. 2. Ascospores developing sprout mycelium in nutritive 

 solution. 3. Sprout cells. 4. Sprout cells developing in groups. 5. Hypha forming 

 sprout cells. 6. Sprout cells changing to chains of gemmae. (X 350; after Brefcld.) 



tabifica causing dry heart rot and leaf spot of beets and sugar beets, has 

 Phoma Betae, on the roots, and Phyll osticta tabifica, in the leave as its 

 imperfect forms. 



In the remaining purely "sphaerial" Mycosphaerellaceae, only four 

 pathogenic genera are discussed: Venturia (ascospores, as in Myco- 

 sphaerella, divided into two equal cells, perithecial hairy, paraphyses 

 present), Guignardia (ascospores divided into two unequal cells), Dilophia 

 and Sphaerulina (ascospores multicellular). Venturia inaequalis causes 

 apple scab; its imperfect form is Fusicladium dendriticum. Guignardia 

 Bidwellii causes black rot of grapes; it forms micro- and macroconidia in 



