46 Bulletin 313 



Mycosph^.rella sentina (Fr.) Schr. {-= Septoria piricola 

 Desm., page 92). — On the leaves of pear and apple. In conidial 

 stage causes angular spots of various sizes (depending on host) 

 with ashy-gray centers surrounded by brown or black zone and 

 sometimes an outer purple zone. These color zones are frequently 

 lost in older leaves. Pycnidia ovate, minute, black, on both sur- 

 faces of ashy-gray centers; conidiophores hyaline, conidia filiform, 

 usually curved, 2-septate 40-60 x 3-4 fx. Perithecia crowded, black, 

 numerous, on under side of dead spots of over-wintered leaves, long 

 ostiole, erumpent, 80-110 [x; asci colorless, clavate, frequently 

 slightly curved, base variable in form, 60-75 x 11-13 /*; ascospores 

 fusiform, straight or very slightly curved, 1-septate, cells equal, 

 26-33 X 4 /i. 



202. Infected leaf of pear. 203. Conidia, 1/12. 204. Perithecia, 1/12. 205. 

 Asci, 1/12. 206. Ascospores, 1/12. 



Pleospora hyalospora E. & E. — On the leaves of alfalfa.* 

 Causes brown to whitish, oblong or marginal leaf spots. Perithecia 

 scattered, depressed, hemispherical, papilliform ostiolum erumpent, 

 75-90 fi. Asci oblong, 75-85 x 35-40 /a. Ascospores oblong to ovate, 

 ends rounded, 3-6 sptate with one or more longitudinal septa, 

 slightly constricted at septa, 25-41 x 12-20 fi. 



Note : — It is well known that Alternaria is sometimes the conidial 

 stage of the species of this genus. We found an Alternaria con- 

 stantly associated with this species, but did not prove its connec- 

 tion by culture and inoculation. 



207. Infected leaves of alfalfa. 208. Ascus, 1/12. 209. Ascospores, 1/12. 

 210. Germinating ascospores, 1/12. 211. Perithecium, 1/6. 212. Cross-section 

 of leaflet showing Alternaria associated with Pleospora, 2/3. 213. Conidio- 

 phores of same, 1/12. 214. Conidium of same, 1/12. 215. Germinating spore 

 of same, 1/12. 



Physalospora cydoni^ Arnaud. — The perfect stage of SphcErop- 

 sis nialorum, page 78. 



*Apparently tlie same as P. Iiyalospora reported on Lathyrus sativns and 

 Pisum sativum. 



