IOWA ACADEMY OP SCIENCE 
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Grain Rust. There is every evidence that rusts, in particular Puccinia 
graminis and P. coronata are more common in very moist soils than in drier 
places. We have observed rust very severe in low fields, when on adjacent 
and higher ground there was less rust. The poorly drained fields always 
suffered more than the soils well drained. Mycological literature is abun- 
dant on this point. 
WEATHER AND FUNGUS DISEASES. 
The weather refers to the state of the atmosphere; it has reference to 
degrees of warmth, cold, moisture and drought. Certain conditions of weather 
are often responsible for wide spread epidemics of plant diseases. Where the 
organic matter of the soil undergoes rapid disintegration accompanied by 
humid, warm conditions the small grains are affected with rust. The warm 
humid conditions always lead to the attacks of downy mildews. Cool weather 
though accompanied by frequent rains is not conducive to the severe attacks 
of rust. 
Dr. Halsted^® reports that after an early spring of unusual cloudiness and 
precipitation in New Jersey in the year 1898, the hollyhock rust was very 
abundant and destructive; cedar apple fungus of great frequency; exoascus 
remarkably abundant; peach curl never before so wide-spread. 
The years 1891 and 1892 were dry ones in which there was no outbreak of 
fungous troubles; the year 1894 had a dry summer. The year was remarkable 
for a most widespread and destructive fire-blight. The month of May had 
unusual precipitation followed by a superheated period of ten days. Then 
came the blight, which seriously affected all pear orchards. In the same year 
cherry leaf spot disease are unusually abundant. 
The year 1896 was dry, with June and July rainy. During this time 
asparagus rust spread in Eastern United States to an alarming extent. 
Dr. Paul Sorauer®® in a discussion of the problems connected with the 
sensitiveness of plants with regard to parasitic fungi, notes that the attacks 
are due to the injuries of frost, etc., and that frost is one of the most potent 
factors in connection with the attacks of fungi. Plants that are variously 
colored or blanched are much more subject to diseases than the green plants. 
This writer considers that it is important to consider plant hygiene, to prevent 
disease by culture and to develop immunity. 
He states that in the winter of 1900-01, there was little frost in Germany, 
but from observations made by numerous persons in Germany it was found that 
where the eastern and the northern winds removed the snow that the plants 
on such places became more affected with rusts; furthermore that a heavy soil 
containing considerable moisture when grain was sown early was less subject 
to rust than other places. An experiment made with rye indicated that when 
the moisture is too great and the temperature too high that the plants were 
affected very much as with frost. 
Dr. A. B. Prank®^ in a paper on the subject of rusts gives as the character- 
istic influences of this disease the following; “That the spores of the rust 
^^The Influence of Wet Weather upon Parasitic Fungi. Bull. Torr. Bot. Club. 26 : 
381-389. 
3®Mitt. d. Deut. Landw. Gesellsch. 1900 :185. 
®^Nachrichten a. b. Klub d. Landw. 1898:388-389. 
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