PLANTS OF IOWA 29 



Phyllactinia, Lev. 



292. P. suffulta, (Reb.) Sacc. 



Abundant on Fraxinus americana, August and Sep- 

 tember. 

 Uncinula, Lev. 



293. U. necator, (Schw.) Burrill. 



Common on Vitis labrusca, Concord, Worden and espe- 

 cially Roger hybrids (Agawam). 



294. U. adunca, Lev. 

 On willow leaves. 



295. U. ampelopsidis, Peck. 



On Virginia creeper leaves. Powder mildew of the 

 grape. 



296. U. americana, Howe. 



On grape leaves and pedicels. 



297. V. circinata, C. and Pk. 

 On Silver Maple leaves. 



298. U. clintonii, Peck. 



On Tilia americana, not very common. 



PERISPORIACE^E FAMILY. 



Podosph^era, Kunze. 



299. P. oxyacanthce, (DC.) DeBy. 



Abundant on cultivated Prunus cerasus and P. pumila. 

 Not common on U. americana; also observed on young 

 shoots of Cratcegus punctata, and C. mollis; July, 

 August and September. Powdery mildew of the 

 apple, plum and cherry. 



300. P. tridactyla, D. By. 



Abundant on the leaves of seedling cherries and apples. 



Microsphjsra, Lev. 



301. M. alni, (DC.) Wint. 



Abundant on Syringa vulgaris, S. persica, August and 



September. 



302. M. quercinia, (Schw.) Burrill. 

 On White, Burr and Pin oaks. 



