PHYCOMYCETES OF IOWA 
285 
Cystopus tragopogonis (Per). Schr. 
^Ambrosia artemisiifolia. “Abundant in June and early July.” Hal- 
sted (10) reports the presence of the disease in 1888 on the above host, 
saying that this species of the fungus is the least common of the whole 
genus and was comparatively rare during the past two years. 
^Ambrosia psilostachya (3). 
Artemisia biennis. Reported by Halsted on this host in 1885 (13). 
^Parthenium integr.i folium (3). 
Peronosporaceae 
Phytophthora infestans (Mont.) D. By. 
Solanum tuberosum (3). Stewart; Greenfield, 1903. Griffith; West 
Point, 1903. Halsted (2), (10) reporting this disease in 1886 says “it is 
the cause of potato rot. It has not been as prevalent as last year. The 
season has been dry and unfavorable to the development of the rot. Po- 
tatoes stored in cellars and pits where tubers rotted last winter are be- 
ginning to decay.” Again in 1888 he reports that “there were no signs 
of the disease last season.” “Past two seasons dry. Two years ago many 
complaints from all parts of the state. More than half of the potatoes 
in some sections rotted either before they were dug or in storage.” 
Phytophthora omnivora D. By. 
Panax quinquefolium. Melhus. 
Sclerospora graminicola (Sacc.) Schroet. 
Setaria Itaiica (3). Pammel; Ames, August, 1889. 
Setaria viridis (2), (3). Ames, August, 1889. Pammel; Ames, 1890, 
August, 1891. Combs; Ames, August, 1894. Pammel; Turin, September, 
1894. Pammel; Jefferson, July, 1895. Pammel; Steamboat Rock, Sep- 
tember, 1901. Pammel; Ames, 1911. Melhus; September, 1916. “Abun- 
ant during the latter part of May till middle of June, destroying large num- 
bers of young plants of the above host. In whole patches it prevented 
the maturing of seeds.” (4). “Not as common as in 1892. That year it 
took away whole patches of that miserable weed. After the fall rains in 
August the fungus increased somewhat.” (8). “Common throughout the 
state in 1899.” (9). Halsted (10) reported the presence of the disease in 
1888. Less common that particular season. 
Plasmopara viticola (B. and C.) B. and DT. 
Vitis sp. Bakke ; Ames, September, 1907. 
Vitis labrusca (3) . Bradford; Ames, 1911. Pammel; Boone, September, 
1912. 
Vitis vulpina (3). Bakke; Ames, September, 1907. “The frosty grape 
mildew has not been found on the cultivated grapes in this vicinity this 
season. In the spring the violent form of this fungus was discovered upon 
the leaves and canes of the common wildgrape (Vitis vulpina). Canes 
were dwarfed and covered with a white coat of conidial spores. Could 
not be propagated on the cultivated forms.” (2). Halsted (10) in 1888 
reports that two years previous to this date the canes of Vitis vulpina 
were dwarfed and covered with a thick coat of white, down to the earth’s 
surface. None was found in 1887. Bessey (1) reports this disease in 
1884 as follows. “Common from mid summer to autumn on leaves and 
young twigs.” Destructive in 1902-03. (3). So abundant in 1892-93 as 
to threaten the cultivated grape (8). 
Vitis bicolor. Pammel; McGregor, Iowa. June, 1920. 
Psedera quinque folia. Pammel ; Ames, Cedar Rapids. 
Plasmopara Halstedii Farl. B. and T. 
“On many composites” (1). 
Ambrosia artemisiifolia (3) (6). 
^Ambrosia trifida (6). 
^Bidens cernua (6). 
^Bidens chrysanthemoides (6). 
