7 
By month this gives for— 
Inch. 
April. 1. 22 
May. 4.55 
June. 2.40 
July. 4.17 
Inch. 
August. 2.54 
September.16 
Total. 15. 04 
It will be noticed that while in 1887 there were only three rains of over 
an inch in the growing season, during the past year the record shows 
seven. The most marked difference was in May, when 4.55 inches of 
1888 stands in contrast with 1.39 inches of 1887. It should be kept in 
mind that May is the time when rains, if not in excess, do the greatest 
amount of good, as vegetation then is in a condition to profit most from 
showers. The amount in June remains about the same, but that for 
July and August is nearly double. The species of Peronosporece are 
taken up one by one, as this seems the best method of exhibiting the 
contrasts. 
Phytophthora infestans, DBr. Three years ago, after an aver¬ 
age season, there was much complaint of the rot iu all parts of Iowa, 
and housed tubers contained the parasite in abundance. The potato 
crop for 1888 was very heavy, and no rot has been seen by or reported 
to me. The two very dry years, viz, 1886 and 1887, doubtless have 
greatly reduced the number and vitality of the rot spores, and done 
more than an average season to rapidly develop the rot. 
Peronospora viticola, DBy. None of this mildew of the grape 
was found last year, although the search for it was frequently made, 
and in places where two years before the wild canes of Vitis riparia , 
were dwarfed and covered with a thick white felt down to the earth’s 
surface. No signs of the mildew could be found in the large col¬ 
lege vineyard, where many sorts of cultivated grapes and a few scat¬ 
tered vines of native wild species are grown. The vines were iu every 
way healthy, and flourished when all vegetation about them was suffer¬ 
ing with drought and heat. This season the cultivated vines suffered 
severely from the mildew, and nearly every leaf was more or less 
affected and the crop much injured. 
Peronospora Halstedii, Farloav, is the most wide-spread species 
in Iowa. Its hosts are numerous, the leading ones of which are several 
species of Heliantlius , Silphium , Eupatorium , Bidens , and a long list of 
other genera all of the order Composite. In 1386 this mildew was mod¬ 
erately common, but last year it was found only upon those composites 
which were in wet places. It was rare upon Helianthus ; not found at 
all upon Ambrosia artemiskefolia , Solid ago Canadensis , or Eupatorium 
and Silphium species. In short, the genus Bidens was the only one 
which could furnish any considerable supply of specimens. B.frondosa , 
B. chrysanthemoides , and B. connata , var. comosa , all were infested, but 
these hosts grew in beds of streams where plenty of moisture reached 
the rank succulent plants. This year there has been a fair quantity of 
the Compositce mildew upon the high ground plants, especially about 
the middle of June, which may be accounted for by the May rains. 
