PHYCOMYCETES OF IOWA 
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Capsella hursa-pastoris (4), (6), (7). Hitchcock; Ames. 
"^Draba Caroliniana (6), (12). 
Lepidium apetalum (6), (7), (12). Ames, 1911. Pammel; Ames, May, 
1918. .... 
Lepidium Virginicum (2), (10). Hitchcock; Ames. 
Lepidium sp. Stewart and Pammel. Anderson; Decatur County, June, 
1904. 
^Radicula palustris (2), (4), (10). 
*Raphanus sativus (6) . 
. Sisymbrium canescens (4). 
Sisymbrium officinale (6). 
‘‘Brassica nigra and Radicula palustris were added to the list of hosts for 
Iowa in 1888. Another oosporic host, Lepidium Virginicum, also was 
added the same season. Oospores were first found that year, June 28 (2). 
“Abundant on leaves and stems of Lepidium apetalum and L. Virginicum, 
killing the hosts.” (6) . “Abundant in April and May on leaves of Lepidium 
apetalum, completely infesting the whole plant, giving them a yellow ap- 
pearance and stunted growth. It also occurred on Capsella bursa- past oris 
but less abundantly” (7). “Is one of our most common species upon var- 
ious cruciferous hosts. In ordinary seasons Lepidium Virginicum is much 
infested and has its branches strangely distorted. This year the pepper- 
grass has been quite free from attacks excepting the seedlings which for 
a few weeks were badly infested in the spring. This species lives over the 
winter in these seedlings and when spring comes the mildewed plants com- 
municate the trouble to other plants by means of the multitude of con- 
idial spores. The vigor of its attack upon the young pepper-grass makes 
this mildew one of the useful weed-destroyers. It deals in the same way 
with the shepherd’s purse. Of all its hosts it has been most abundant upon 
Radicula palustris. In some species examined the conidiospores were not 
more than one-fourth the normal size. Other parts of the same patch, 
however, showed all gradations and it may be observed that a leaf parasite 
may be dwarfed as well as its host.” (10). 
Peronospora effusa (Grev.) Rabh. 
*Cheno podium sp. (1). 
Cheno podium album (10). Dwigans; Ames, October, 1899. Hitchcock; 
Ames. Halsted found it 'on this host at Spirit Eake in 1885. Mature 
oospores were found on the leaves (5). 
Plantago major. Pammel; Ames, June, 1909. 
Peronospora sordida B. and Br. 
Scrophularia nodosa (4). Bessey; Ames, October, 1882. “Has been a 
good illustration of the influence of moisture on mildew. The host Scro- 
phularia nodosa is a common plant on the banks of streams, especially 
when the slope is steep and without sod. The peronospora was frequently 
looked for, but it appeared in its usual abundance in only one place and 
this was at the bend in a stream, where the host grew close to the water” 
( 10 ). 
Peronospora viciae (Berk.) D.By. 
Vida Americana. Hitchcock; Ames. “Abundant in the latter part of 
May and early June on this host.” 
Peronospora trifoliorum D.By. 
^Astragalus canadensis (4). 
Medicago saliva. Schultz; Postville, June, 1914. 
Vida Americana (1), (4), “Abundant early in summer. Unable to 
propagate well in 3 per cent sugar solution”. (2). “Has heretofore been 
a common species upon Astragalus canadensis and especially on Vida 
Americana. Upon the latter it was so abundant two years ago as to al- 
most destroy the host in whole patches. This year it was obtained only 
after a long search in the moistest places in which the vetch will grow.” 
( 10 ). 
