1912. 
THE RURAL NEW-YORKER 
*30© 
HOP MILDEW AND ITS CONTROL. 
Life History of a Destructive Fungus. 
In a previous article in this paper reference has 
been made to a very destructive disease of hops in 
New York State, namely the “hop mildew'’ or “mold” 
caused by the fungus Sphaerotheca Humuli (Dc). Burr. 
The present article will deal more particularly with 
the symptoms of the disease, the life history of the 
fungus causing it, and results obtained in controlling 
it. 
The disease appears usually first on leaves near 
the ground as white powdery spots. These are at first 
round in outline, but grow rapidly and soon many 
spots run together, forming large, irregular patches, 
Fig. 269. These first few spots appear harmless 
enough, but once the rapid spread of the disease and 
its blighting effect have been experienced the first 
signs of the disease are indeed alarming. Often dur¬ 
ing the past season, where, nothing was done to 
prevent its spread, the leaves were completely covered 
in less than a week after the first appearance of the 
spots was noticed. In a yard where the attack of 
mildew is early, coming from the old leaves on the 
ground, the mildew spots appear first on the lower 
leaves, and from these rapidly spread to those higher 
on the vines. 
Where the attack is late and evidently caused by 
spores borne in by the wind from other yards, it 
often attacks only the upper leaves and the buds, 
blossoms or young hops. In such cases mildew is 
scarcely noticeable on the lower leaves at all, and 
therefore, such attacks frequently escape 
observation till much damage is done. 
On the leaves the damage to the plant 
is usually comparatively slight, except 
in a few cases where the attack is very 
severe. When the young hops are at¬ 
tacked, however, their development is 
stopped wholly or in part, so that it is 
in this way the greatest injury occurs. 
These mildewed hops appear at picking 
time as hard blackened mummies, or in 
cases of less severe attack only part of 
the hop is dwarfed in this way, Fig. 271. 
The life cycle of the fungus - causing 
this disease may be briefly traced as fol¬ 
lows : The fungus is carried over Winter 
by a thick-walled case containing a sin¬ 
gle-walled sac which contains eight spores 
A MILDEWED HOP LEAF. Fig. 269. 
checked here by application of sulphur. Large yards 
at Middleburgh that suffered severe losses* in 1910 
were sulphured six times, beginning about the last 
of June. These yards suffered no appreciable loss 
in 1911, although severely attacked in 1910, although 
the mildew had a slight start before the sulphuring 
A bove Dusted; 
Below Check; 
Bight Diseased: 
Middle Partly Diseased; 
Deft Healthy. 
RESULTS OF TREATMENT FOR MILDEW. Fig. 270. 
During 
the wet weather of the Spring and early Summer 
this fruit body absorbs water and the inner part ex¬ 
pands, developing a pressure which is sufficient to 
shoot the spores out into the air. Some of these 
are carried to the lower leaves of the plant, where 
they germinate, sending out long branching threads 
or hyphae. These fine white strands grow out in all 
directions on the surface of the leaf, sending short 
branches into the surface layer of leaf cells from 
which they obtain their nourishment. Before the 
hyphae have grown far, short, erect branches are sent 
up in large numbers. These are the conidiophores, 
on the end of which the spores are formed in long 
chains. Thus each spot bears a countless number of 
spores, which are freed with every movement of the 
leaf, and blown about to other leaves to cause further 
infection. This process is kept up throughout the 
Summer. 
In August the thick-walled cases begin to be formed 
again, which serve to carry the fungus over Winter. 
These are formed principally on the under sides of 
the leaves and on the dwarfed hops, where they are 
often several layers deep. These remain on the 
leaves and hops over the Winter scattered about the 
yard, where they are ready to cause infection the 
following Spring. It would thus seem that the more 
thoroughly the old vines were destroyed by burning 
at picking time the less liable the yard would be to 
an early infection in the Spring. This conclusion 
is borne out by the limited number of observations 
that have so far been made. 
During the past year the control of this disease 
was attempted on such a large scale that many inter¬ 
esting observations were made. Liquid spraying was 
practiced only in a few instances on a small scale. 
Potassium sulphide was tried out by one grower in 
the early part of the season, and he found that it 
seemed to check the disease for a time, but had to be 
repeated rather frequently. He later gave up this 
practice and adopted sulphuring as cheaper and more 
effective. 
One instance was of especial interest. A grower 
near Waterville applied dry sulphur to all of his 
yards except one part of about four acres, which was 
the part least attacked by the mildew the year previ¬ 
ous. This was the only part of the yard in which 
the mildew appeared at all in 1911, and was later 
was started in 1911, and although yards surrounding 
these suffered considerably from mildew. Many in¬ 
stances equally interesting might be added to these 
where favorable results were obtained by growers. 
In other instances where the sulphur was not applied 
early enough or less thoroughly, correspondingly poor 
results were secured. 
A four-acre yard near Deansboro was chosen for 
experimental tests of sulphuring. This yard was 
chosen because it was one of the first to be attacked 
by the mildew, and it was desired to carry out as 
severe a test of sulphuring as possible. The first 
sulphuring was done in this yard the first of July, 
when many of the leaves were already covered with- 
mildew. Sulphur was applied six times in all. 
The yard was divided into three portions, to one of 
which sulphur alone was applied, to the second, a 
mixture of sulphur and lime in equal parts, and, to 
the third nothing was applied. The hops on several 
vines in each of these sections were picked, graded 
and counted. Three grades were made of the hops, 
No. 1, including only hops not attacked by the mildew 
at all; No. 2, hops only slightly attacked which had at¬ 
tained nearly or quite their full growth; No. 3, hops 
stunted by mildew and mostly only dried-up mummies, 
entirely valueless. About 20,000 hops were counted 
in making up the following percentages (Fig. 270). 
No. 1 hops. No. 2 hops. No. 3 hops. 
Per cent. Per cent. Per cent. 
Dry sulphur applied. 61.2 28.8 10.0 
Sulphur and lime.12.3 29.4 58.3 
Check . 0.0 2.4 97.6 
From the above tabulation it may be seen that the 
hops on the check plat were ruined entirely by the 
mildew as nearly as the entire yard had been the 
year previous. Perfect control was not secured on 
the sulphured plat, although there were only 10 per 
cent unmarketable. This was not to be 
expected considering the large amount 
of mildew in the yard' when the sul¬ 
phuring was begun. There is every rea¬ 
son to believe that nearly perfect con¬ 
trol can be secured as indicated in in¬ 
stances previously cited: This experi¬ 
ment shows, however, that much may be 
done even after the attack on the 
leaves is severe. Growers should cer¬ 
tainly not wait as late as this to begin 
sulphuring as it was clearly shown last 
year in many instances that sulphur is a 
better preventive than cure. 
In the above tabulation the effect of 
adding lime to the sulphur is clearly 
seen. This effect of lime is such as 
would be anticipated considering the action of the 
sulphur to be due to the sulphurous and sulphuric 
acid formed from the sulphur, since the lime would 
neutralize the acid produced forming compounds only 
slightly soluble. 
The method used in applying the dry sulphur has 
been to blow the sulphur into the air, forming a cloud 
of sulphur which envelops the entire plant and set¬ 
tles on every part. The machine used is fitted with 
a revolving fan geared to the wheels. ' This machine 
is operated by one horse and a man and is capable 
of covering a large acreage per day; The advantage 
that this method has over liquid spraying is that with 
the present diverse methods of training the vines it 
is quite impossible without prohibitive labor expense 
to apply a liquid spray to the vines. This is because 
the hop poles are 20 to 25 feet or more high with 
strings across between the poles so that they could 
be sprayed thoroughly only by the use of spray rods 
operated by hand. As there seems to be little doubt 
as to the value of sulphuring for this disease, the 
work this year will be aimed principally at deter¬ 
mining what kind of sulphur is most effective and 
economical, the frequency of application necessary 
and amounts of sulphur necessary for each applica¬ 
tion. F. M. BLODGETT. 
Cornell University. 
HOP DWARFED BY MILDEW. Fig. 271. 
At the close of last year the property of the National 
Telephone Co., which was capitalized at $77,864,000 and 
gave employment to 18,000 persons, passed under Federal 
control, and by the transfer private telephone ownership, 
excepting a few isolated lines, ceased in the United King¬ 
dom. A night telegraph letter service was instituted 
January 1, 1912, between London and points in Scotland 
and Ireland at the rate of 12 cents per 36 words and 
one cent for every additional three words. Toward the 
end of last year a week-end cable service was inaugurated 
between the United Kingdom, the United States, and Can¬ 
ada at greatly reduced rates. Improved telephonic com¬ 
munication with the Continent was established by the com¬ 
pletion of the new channel cable. 
That is part of a report from Consul-general Grif¬ 
fiths. “Private telephone ozvnership ceased in the 
United Kingdom.” If you judged from the theory of 
government entirely you would say that a monarchy 
would be last to make such a statement possible and 
a republic first. Under a republican form of govern¬ 
ment the people are supposed to rule. Yet here is 
the English government taking public utilities out of 
private hands, while in America these private hands 
get nearer and nearer to the public throat. 
