92 IOWA ACADEMY OF SCIENCES. 



POWDERY MILDEW OF THE APPLE. 



BY L. H . PAMMEL. 



(Abst7-((ct.) 



The past season was very favorable for the development of the Powdery Mil- 

 dews. During the month of September Mr. G. W. Carver, a special student in 

 the botanical laboratory, brought in a fine lot of The Apple Powdery Mildew. An 

 Eri/siphe and the common Powdery Mildew of the cherry, Podosphaora oxyacan- 

 thce, have been reported on Pyrus mains* But our fungus does not belong to 

 either of these genera. It agrees with the descriptions given for Sphterotheca 

 mali (Duby) Burrill. It is easily recognized by its persistent perithecia, two 

 kinds of appendages. The long appendages come from the upper end; they are 

 straight or curved, rigid, usually septate, and occasionally forked at the end The 

 base is deeply colored. The rudimentary appendages are floccose and attached to 

 the smaller end of the pyriform perithecium. Prof. Burrill records this species 

 abundant at times in the Mississippi valley, and first referred it correctly to 

 Duby's Erysiphe mali. Bot Gall, p. 869. 



FURTHER NOTES ON CLADOSPORIUMCARPOPHILUM— VONTHUEMEN. 



L. H. PAMMEL. 



(Abstract.) 



This fungus was first recorded on the native plum (Primus americana), in a 

 short note presented to the Academy some years ago. 



I thought at first that the fungus on the plum and cherry might prove to be a 

 new species, but I cannot see how the fungus diifers materially from that found on 

 the peach. 



This fungus has become a source of considerable annoyance to the cultivation of 

 the americana plums, in many sections of the United States and Canada. Most 

 of the commonly cultivated forms of this specie are affected in Iowa. The DeSoto, 

 Rollingstone and Speer, being attacked with special severity. 



The Wolf plum, which is a variety of Primus americana, is but little subject 

 to the attacks of this fungus. Prunus anQustifoUa and Primus domestica are 

 not affected. Some varieties of Prunus cerasus are also affected. 



*Ellis and Everhart: North American Pyrenomycetes, p. 



