IOWA ACADEMY OF SCIENCE 
55 
During the present season 1908, we notice with particular severity and 
abundance the powdery mildew of the catalpa, plum, and cherry. The common 
powdery mildew of the knotweed has been particularly abundant here for a 
number of years and this season forms no exception to the rule. 
Rmts. The Ash rust was reported by Dr. Bessey as abundant in Iowa in 
1884. The same year it was observed in La Crosse, Wisconsin. Since then it 
has not appeared in these neighborhoods in epidemic form. There must have 
been a great deal of the teleuto stage of the rust. The Puccina pruni-spinosa 
was common in 1889 on a variety of Prunus Americana, the Chippeway in Ames 
and since has rarely been seen. 
Clover Rust. Clover rust upon red clover^® was not observed in Iowa until 
August, 1900, and then upon the “aftermath.” Later it was found quite 
abundantly on the College Farm, the diseased plants being seriously affected. 
How long the fungus has affected red clover plants in this country and in 
Iowa is not known, but it is reported on white clover by Arthur in 1884 and 
was common on this host in Wisconsin in 1883. 
HollyhocTc Rust. The hollyhock rust, native to Chili, was introduced into 
France in 1872, and in a short time became general in Europe. It found its 
way to this country in the year 1886, having been reported from Beverly, Mass. 
Prof. Farlow^® records its earliest appearance in the United States. Holly- 
hocks in the garden of Prof. C. L. Jackson were found to be affected with the 
disease which was introduced with the seeds imported from Europe. In 1887 
it appeared in the Boston Public Garden. A few years later in 1891 it was re- 
ported in New Jersey and New York. This was reported by C. E. Hunn^'^ in 
New York in 1889. The writer found it common on the Pacific coast in 1898. 
This disease has played havoc with hollyhock culture in some parts of the 
United States. 
Asparagus Rust. The Asparagus rust, native to Europe, was unknown to 
this country prior to 1896, when it was reported in the east. Halsted^® and R. 
E. Smith^® think that the rust started in an epidemic from the North Atlantic 
states during the fall of 1896. It is now a most destructive enemy to the 
culture of this plant. 
Downy and Powdery Mildews. The Downy Mildew of the grape was un- 
known in Europe before the introduction of the American grape vines to resist 
the attack of the Phylloxera. Mr. Salmon gives an interesting account of the 
spread of the gooseberry mildew in Europe which he thinks may be due to 
importation of American plants. 
The potato rot fungus infestans) was unknown to the botan- 
ists of Europe before 1845. This soon spread to many of the European coun- 
tries playing havoc with the culture of the potato. 
Apple Blight. Apple and pear blight was practically unknown on the Pacific 
coast until a few years ago. It was unknown according to Ralph E. Smith®® in 
central and northern California but it had wiped out the orchards in the south- 
■‘“lowa Agr. Exp. Sta. Bull. 13 ; 5 1-5 3. 
«Parlow, W. G. Bot. Gaz. ii:309-310. 
disease of the Hollyhock. Rep. N. Y. Agr. Exp. Sta. 1890:335. 
^®The asparagus rust ; its treatment and natural enemies. New Jersey Agr. Exp. Sta. 
Bull. 129:3-20. 
^^Asparagus and asparagus rust in California. Cal. Exp. Sta. Bull. 165:5-99. Rept. 
of Plant Pathologist July 1, 1906. 
50Univ. Cal. Exp. Sta. Bull. 184 :221. 
