476 
THE GARDENERS' CHRONICLE OF AMERICA. 
dens being entirely free from this most destructive of 
all rose diseases. Wild as well as cultivated roses 
Milter from it, crimson ramblers being especially sus- 
ceptible. The fungus frequently appears very earlv in 
the season on young buds, leaves, and young shoots, 
causing the appearance of a delicate white mildew that 
becomes mealy after the development of the summer 
spores. If the attack is severe, the normal develop- 
ment of the succulent young shoots is arrested, the 
leaves become curled and deformed, falling prema- 
turely, and complete defoliation sometimes results. 
Later in the season the Winter spores develop. These 
spores ' are capable of persisting through the winter 
and setting up a new infection in the Spring. 
Rose rust appears as conspicuous, orange-colored 
swellings on the green parts of rose bushes in the 
Spring or early Summer. Later these take a deeper 
shade and become powdery. Small, circular spots 
may occur on the leaves. 
Anthracnose attacks 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. 
There are several leaf-spot diseases of roses. In 
most cases the spots have a more or less brownish 
center with a purplish border. 
Leaf-blotch, which is also known as black-spot, ranks 
next to powdery mildew in frequency 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 
definite borders on the upper surface of mature or 
nearly full grown leaves. These spots may grow to- 
gether so as to cover almost the entire leaf. 
Practically all these diseases require the same treat- 
ment, 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, fol- 
lowed by more spraying of the shortened plant. The 
diseased 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 during the 
growing season. 
For powdery mildew, the control sprayings should 
be with lime-sulphur or potassium sulphide. After 
cutting back in the Fall, a similar spray should be made 
use of. The control spraying for rusts should lie am- 
moniacal copper carbonate. The Fall spraying should 
be with a strong Bordeaux mixture. For leaf-spot and 
leaf-blight, the control sprays may be either Bordeaux 
or ammoniacal copper carbonate, 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 disease. The early symptoms are 
the appearance of small reddish patches 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 cer- 
tain 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 for 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 
surfaces thus made by this cutting with paint or tar. 
This diseased material must be burned and the dor- 
mant bushes sprayed with strong Bordeaux mixture 
in both the Autumn and early Spring. At the first ap- 
pearance of the disease, cut away and destroy all the 
branches showing infection. Then spray about every 
10 days, first with Bordeaux mixture and later with 
ammoniacal copper carbonate. 
T l 
WHAT HOUSE PLANTS REQUIRE. 
HERL is no home to which some plant is not adapted, 
and while conditions for its growth may not be 
ideal, its culture is not impossible. Ignorance of cultural 
details even in a proper environment has resulted in the 
elimination of many house plants which otherwise would 
have endured and become a source of attraction and of 
pleasure to their owner. Plant culture demands the ap- 
plication of intelligence. Commonsense methods are 
necessary for success. 
Negligence in cultural details is likewise a derogatory 
factor. The rooms must not be stuffy, the windows must 
on favorable occasions be opened, the blinds should not 
be drawn until dark, or left down too long in the morn- 
ing. A fairly even temperature must be maintained. At- 
mospheric humidity must lie created by placing pans of 
water on the radiators, stoves, furnaces, or near the re- 
gisters. Cleanliness is also essential, neglect of this will 
result disastrously. Plants breathe through the pores of 
their leaves, one-half of their food material is absorbed 
in this manner (carbon). They should, therefore, be 
sprayed or sponged to remove the dust which clogs the 
pores, remembering at all times that it is as necessary 
to clean the under surfaces as the upper surfaces of the 
leaves. The surroundings must be cleanly and whole- 
some. The dictionary indicates that surroundings are 
but the environment. The scientist says environment gov- 
erns or influences development and growth. To neglect 
the foregoing conditions must be to court failure, as these 
are the things which constitute environment. 
Having chosen your plants, observe the following sug- 
gestions. Learn them by heart. Light is essential to 
green plants in that through its influence they are alone 
able to assimilate their food. Plants can only perform 
their functions within certain limits of temperature. Keep 
an eye on the thermometer, there is a temperature called 
the potimum, at which the absorption of food materials 
and consequent assimilation ( under the influence of light ) 
and growth proceeds more rapidly than at any other time. 
The most favorable average temperatures are 55 to 60 
degrees F. by night, and 60 to 70 degrees F. by dav. 
Fresh air is necessary, for from it the plant extracts 
its carbon and some of its oxygen (carbon dioxide); 
without oxygen it cannot perform its life functions. Do 
not forget this, but when opening the windows do not 
create draughts which chill. It is better for cold air to 
be warmed by contact with that of the room ere it reaches 
the plants, therefore, ventilate carefullv. Keep the at- 
mosphere charged with moisture; it prevents excessive 
transpiration of water through the plant cells, especially 
at night. Transpiration should be reduced to a minimum 
at this time, as only during daylight is it of great im- 
portance in promoting growth. 
Plants rest at night, and while resting their food is di- 
gested, the starch they have formed by day is changed in 
the leaf cells to sugar, this being the first step in the 
formation of organic food material. Pay careful atten- 
tion to the many details of potting, watering, spraying, 
and fertilizing; it is worth while, as it will lead you to a 
study and eventually to a love of your plants. You will 
soon understand their requirements, and learn from ex- 
perience much more than can be taught by word of mouth 
or scrawl of pen. — Canadian Horticulturist. 
