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71. Podosphaera' oxyaoanthae (DC.) De Bary. 
On Prunus americana Marsh, P. avium L., P. besseyi Bailey, 
P. eerasus L. Often does some damage to the cherry. Is 
quite common. 
72. Podosphaera leucotricha (Ell. & Ever.) Salmon. 
On Mai us malus (L.) Britton. This species injures young trees 
and sprouts, etc. 
73. Erysiphie polygoni D C. 
On Astragalus carolinianus L., Brassica nigra (L.) Koch, 
Clematis virginiama L., Falcata pitcheri (T. & G.) Kunze, 
Pisuin sativum L. ; Polygonum aviculare L., P. erectum L., 
Ranunculus abortivus L., Thalictrum purpurascens L. This 
species often proves very destructive on the pea. 
74. Erysiphe cichoracearum D C. 
On Ambrosia artemisiaiefolia L., A trifida L., A trifida integri- 
folia (Muhl.) T. & G., Aster laevis L,, Carduus discolor 
(Muhl.) Nutt., Galium circaezans Miehx., Helenium aut- 
umnale L. ; Helianthus grosse-serratus Martens, H. tuberosus 
L., Phlox divarieatia L., Plantago major L., P. rugelii Dec., 
Verbena hastata L., V. stricta Vent., V. urticifolia L., Ver- 
besina alternifolia (L.) Britt. This is a very abundant 
species but as most of the hosts attacked are weeds it cannot 
be considered as causing damage. 
75. Erysiphe graminis DC. 
On Poa pratensis L. Quite common. 
76. Erysiphe taurica Lev. 
On Heliopsis scabra Dunal. Common. 
77. Microsphaera alni (V T allr.) Wint. 
On Corylus americana L., Lonicera sullivantii A. Gray, Ostrya 
virginica (Mill.) Willd., Quercus rubra L., Syringia vulgaris 
L. Very common, especially on the lilac. 
78. Microsphaera alni vaecinii (Schwein.) Salmon. 
On Catalpa speciosa "Wardr. Destructive but not very common. 
79. Microsphaere alni extensa (Cooke & Peck) Salmon. 
On Quercus prinoides Willd. Not very destructive. 
80. Microsphaera diffusa Cooke and Peck. 
On Meibomia canadensis (L.) Kuntze, and Symphoricarpos 
vulgaris Miehx. Common. 
