February, 1917 
WISCONSIN HORTICULTURE 
87 
cations, by turning under as many 
as possible by clean cultivation in 
the spring before the spores or 
seeds of the fungus are set free. 
Our studies of the fungus have 
shown that under Wisconsin condi- 
tions spores begin to be discharged 
into the air at about the time the 
blossom buds of the cherry break 
open ; so cultivation should precede 
this. Most Wisconsin growers cul- 
tivate at about this time anyway. 
Therefore, much may be gained, 
with little additional expense, by 
making the cultivation as clean as 
possible, instead of leaving unturn- 
ed strips or large blocks about the 
bases of trees. 
CONDUCTING SPRAYING EXPERIMENTS 
“During the past season spray- 
ing experiments were conducted 
with the following aims: (1) to 
find the time and number of appli- 
cations and the concentration of 
Bordeaux mixture necessary for 
most economical and efficient con- 
trol, and (2) to develop, if possible, 
a spray treatment which may be 
satisfactorily substituted for the 
Bordeaux treatment, should high 
prices of copper sulphate or other 
reasons make this desirable. While 
it is not possible to draw final con- 
clusions from this work until it 
can be repeated under the condi- 
tions of other seasons, the control 
of this disease is of such practical 
importance that the following 
brief statement of the more import- 
ant results to date seem desirable : 
“In connection with these re- 
sults, it is important to remember 
that leaf spot (“yellow leaf”) was 
unusually severe in its outbreak 
early in the season, but made little 
progress, even on unsprayed trees, 
after the hot dry weather came on 
in late July. At this time unspray- 
ed check trees in the same orchard 
with the experimentally sprayed 
trees had lost more than 60% of 
their leaves, and the remaining 
foliage was badly diseased. Counts 
made on one unsprayed tree on 
July 14 showed that it had al- 
ready lost over 95% of its leaves. 
Such trees failed to mature their 
fruit and went into the winter in 
very bad condition. While infec- 
tion was heavy throughout the sec- 
tion during early summer it was 
unusually severe in this experi- 
mental orchard, because the heav- 
ily infested leaves of the year be- 
fore were purposely left undisturb- 
ed to furnish an abundant source 
of infection, and to make the test 
of the sprays as severe as possible. 
“Time and Number of Treat- 
ments. Bordeaux mixture, 4-4-50 
(4 lbs. copper sulphate and 4 lbs. 
of lime in 50 gals.), was applied: 
(1) just before the blossoms open- 
ed, (2) just after the petals fell, 
(3) about two weeks later, and (4) 
just after the fruit was picked. In 
these and all other applications ar- 
senate of lead powder, at the rate 
of 3/4 lbs. in 50 gallons Avas added 
to the fungicide. On the trees 
which received all four treatments 
the disease Avas controlled excel- 
lently. Where the treatment be- 
fore the blossoms opened \\ r as left 
off, the control Avas as satisfactory 
as Avhere the full four treatments 
were given. Where the second or 
third treatment was omitted, the 
disease Avas not controlled, and 
much foliage) Avas lost. Where the 
last treatment Avas omitted, the re- 
sults Avere about as good as Avhere 
it was applied. It should be re- 
membered, hoAvever, that the dis- 
ease Avas checked by hot weather 
before this treatment Avas applied, 
and made little further progress 
even on unsprayed trees. 
“These results sIioav that, under 
the conditions of these experi- 
ments, the treatment before the 
blossoms opened Avas of little, if 
any, value for leaf spot control, 
and that the disease Avas Avell con- 
trolled by Iavo applications of Bor- 
deaux, 4-4-50, (1) just after the 
petals fell, and (2) about two 
weeks later. There is every proba- 
bility, however, that an additional 
application after harvest Avould 
have been needed, but for the 
checking of the fungus by the hot 
dry Aveather. 
“In timing the first treatment, it 
is very desirable to Avait as long as 
safety permits, in order to cover 
as much of the rapidly increasing 
leaf surface as possible. To test 
the effect of delayed applications, a 
plot Avas sprayed only tAvice Avith 
Bordeaux mixture, 4-4-50, (1) 
about 8 days after the petals fell, 
and (2) about three weeks later. 
At the time of the first spray, 
therefore, the trees Avere in practi- 
cally full foliage. The disease Avas 
controlled as well on this plat as 
where the four treatments were 
given. Again, hoAvever, it should 
be remembered that a treatment af- 
ter harvest might have been nec- 
essary under other seasonal condi- 
tions. 
“The Concentration of the 
Spray. Plats were sprayed com- 
paratively with Bordeaux, 4-4-50, 
3-3-50, 2-2-50 and 1-1-50. The 
3-3-50 formula gave as good results 
as did the 4-4-50, and the 2-2-50 
Avas only very slightly less ef- 
fective. The 1-1-50 formula Avas 
too weak for satisfactory results, 
but even that strength gave a fair 
control. It seems highly probable, 
therefore, that groAvers may be able 
to save spray material, Avithout loss 
of efficiency of the treatment. The 
3-3-50 formula appeal’s to be safe 
to recommend, but weaker for- 
mulas should be used only experi- 
mentally until further evidence is 
at hand. 
TRY SUBSTITUTES FOR BORDEAUX 
“In the attempt to find a treat- 
ment that might be substituted for 
(Continued on page 90). 
