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of peas, caused by Erysiphe Polygoni DeCandolle; 
of lilac, caused by Microsphaera Alni (Wallroth) Winter; 
of bittersweet, caused by Phyllactinia Corylea Karsten. Besides 
the genera above represented, two more, Uncinula and Podosphaera 
are known, species of which occur on trees or shrubs of the yard 
and garden. Examples:—Podosphaera Oxyacanthae (DeCandolle) de 
Bary, on species of Crataegus, Prunus, Spirea and others; Uncinula Salicts 
(DeCandolle) Winter, on species of Salix and Populus. 
Life-history. The powdery mildew fungi exhibit such similarity in 
structure and life-habits that the same outline will serve for the study of 
the life-history of any of them. From this point the student will follow 
the outline as given for the Powdery Mildews of Trees and Fruits, p. 125, 
including the subject designated for the report. 
