'I, 
WISCONSIN HORTICULTURE 
159 
June, 1917 
disease for the growing season will 
be in a great measure controlled, 
the full benefit of fungicidal appli- 
I cations can only be secured by their 
| early use in the spring, guarding in 
'! this way against the recurrence of a 
disease of the previous season. 
Fungicides to be recommended 
for rose diseases are Bordeaux mix- 
ture, lime-sulphur, potassium sul- 
phid, and ammoniacal solution of 
f| copper carbonate. The lime-sul- 
phur has proved very valuable, es- 
, pecially in controlling mildew, as it 
does not injure the foliage of even 
delicate tea roses. 
Powdery mildew. — Powdery mil - 
j dew is extremely common, few gar- 
<J dens being entirely free from this 
I most destructive of all rose diseases. 
R Wild as well as cultivated roses 
I suffer from it, crimson ramblers be- 
1 ing especially susceptible. The 
1 fungus frequently appears very 
I early in the season on young buds, 
I leaves, and young shoots causing 
I the appearance of a delicate white 
I mildew that becomes mealy after 
I the development of the summer 
I spores. If the attack is severe, the 
1 normal development of the succu- 
I lent voung shoots is arrested, the 
I leaves become curled and deformed, 
I falling prematurely, and complete 
I defoliation sometimes results. Lat- 
1 er in the season the winter spores 
I develop. These spores are capable 
I of persisting through the winter 
I and setting up a new infection in 
I the spring. 
Pose rusts . — Rose rust appears as 
I conspicuous, orange-colored swell- 
I ings on the green parts of rose 
K bushes in the spring or early sum- 
I mer. Later these take a deeper 
I shade and become powdery. Small, 
1 circular spots may occur on the 
I leaves. 
Anthracnose. — Anthracnose at- 
tacks principally the leaves, but 
also, to some extent, the branches, 
causing the appearance of blotches, 
which later discharge a pinkish 
mass of spores. The affected leaves 
are dwarfed and fall. 
Leaf-spot. There arc several 
leaf-spot diseases of roses. In most 
cases the spots have a more or less 
brownish center with a purplish 
border. 
Leaf -blotch. — Leaf -blotch, which 
is also known as black-spot, ranks 
next to powdery mildew in frequen- 
cy of occurrence. Bush roses are 
more susceptible to this trouble 
than climbing roses and the attacks 
are most severe in wet seasons. 
The first symptoms of the presence 
of the parasite are irregularly 
shaped blackish spots without def- 
inite borders on the upper surface 
of mature or nearly full grown 
leaves. These spots may grow to- 
gether so as to cover almost the en- 
tire leaf. 
Practically all these diseases re- 
quire the same treatment, which 
consists, in general, of careful 
spraying for control during the 
growing season and the cutting out 
of diseased portions of the plant in 
the fall, followed by more spraying 
of the shortened plant. The dis- 
eased wood removed, together with 
the old leaves and debris under 
bushes, should be burned. In case 
of attacks by rusts and leaf spots, 
the diseased wood or leaves should 
be removed and burned even dur- 
ing the growing season. 
For powdery mildew, the control 
sprayings should be with lime-sul- 
phur or potassium sulphid. After 
cutting back in the fall, a similar 
spray should be made use of. The 
control spraying for rusts should be 
ammoniacal copper carbonate. The 
fall spraying should be with a 
strong Bordeaux mixture. For 
leaf-spot and leaf-blight, the con- 
trol sprays may be either Bordeaux 
mixture or ammoniacal copper car- 
bonate, and the fall spraying 
should be with the former. 
Another disease to which roses 
are subject is canker. A wholly 
satisfactory method of control has 
not been worked out for this dis- 
ease. The early symptoms are the 
appearance of small reddish patch- 
es on the green parts, generally of 
1 -year-old growth. The disease is 
caused by a fungus classed as a 
wound parasite, that is, the spores 
gain entrance to the bush through 
certain mechanical injuries. These 
may be slight ones made upon the 
young branches by the thorns of the 
bush itself when one branch has 
been blown against another, or by 
insect punctures. Such infected 
areas may increase until the entire 
stem is surrounded and may extend 
tor several inches along the branch. 
The only advice to be given is to 
cut away rigorously all diseased 
branches, and it may be necessary 
to cut back entire bushes if badly 
infected. Cover the exposed sur- 
faces made by this cutting with 
paint or tar. This diseased mate- 
rial must be pruned and the dor- 
mant bushes sprayed with strong 
Bordeaux mixture in both the au- 
tumn and early spring. At the first 
appearance of the disease, cut away 
and destroy all the branches show- 
ing infection. Then spray about 
every 10 days, first with Bordeaux 
mixture and later with ammoniacal 
copper carbonate, as spraying has 
no disfiguring effect upon the foli- 
age, an appearance to be avoided 
when blossoming time is near. It 
is possible that by such careful at- 
tention the bushes may outgrow the 
disease. 
Insect Enemies of Roses and How 
to Combat Them. 
In the path to easy success with 
roses lie numerous insect pests 
which, unless prevented, will de- 
vour leaves or suck juices, thus 
