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IOWA ACADEMY OF SCIENCE 
wide, appendages few, sometimes obsolete, very short, tortuous, pale brown, 
septate. Ascus 88-115x0-75 micra. Spores 8, 20-27x12-15 micra. 
On Rosa blanda Ait. Fayette, Aug., 1894 (Fink). 
On Rosa sp., Decatur Co., Nov. 18, 1905 (Anderson). 
This species has been much confused with S. humuli and S. mors - 
uvae. Bessey and Hitchcock report it on species of Ribes but S. 
mors-uvae was undoubtedly the species intended. S. humuli occurs 
on the leaves of roses. S. pannosa in its conidial stage often attacks 
the entire end of the growing shoot of Crimson Rambler roses and 
thus does much damage to this variety as it is very common here 
in Decatur County. I have not observed it as destructive to other 
varieties. I have found the colored mycelium and perithecia only 
on the stems. 
4. Sphaerotheca mors-uvae (Schwein), Berk and Curt. 
See Plate II. 
Sphaerotheca pannosa Lev. Bessey, Prel. List, Ames Flora; Hitchcock, Par- 
tial List Iowa Powdery Mildews. 
Sphaerotheca mors-uvae (Schwein), Berk and Curt. Bessey, The Erysiphei, 
Fink, Blight, etc., of Fayette. 
Mycelium abundant, at first white, becoming dark brown; forming dense 
patches on the fruit, stem and leaves. Perithecia mostly on the stem and 
fruit, gregarious, immersed in the persistent mycelium, 76-100 micra in 
diameter, cells 10-25 micra wide. Appendages few, pale brown, short and 
tortuous, rarely more numerous and longer. Ascus, 70-92x50-62 micra, rarely 
longer. Spores 20-25x12-15 micra. , 
On Ribes cynosbati L. Ames, July 3, 1876 (Bessey) ; Fayette, June 23 and 
29, 1894 (Fink). 
On Ribes gracile Michx. Ames, July 2, 1896 (Carver). 
On Ribes rotundifolium Michx. *Ames, July, 1886 (Hitchcock) ; *Fayette 
(Fink). 
On Ribes sp. Ames * (Bessey), 1894 (Carver); Decatur Co., June, 1904 and 
1905 (Anderson) . 
This species is easily distinguished from all others by the dense, 
dark brown, felted mycelium. It attacks both wild and cultivated 
species of Ribes and is frequently quite injurious, especially to 
some cultivated varieties. 
5. Sphaerotheca phytoptophila, Kellerm & Swingle. 
Mycelium evanescent or subper si stent, perithecia gregarious, 60-78 micra in 
diameter, cells small, about 10 micra wide, often indistinguishable; appendages 
short, more or less tortuous; pale to dark brown, sometimes obsolete or long, 
rarely branched; ascus 60-75x42-50 micra; spores 8, 20-25x12-15 micra. 
