, 1912-07-27
ROSE

the leaves principally on the underside and
causes them to curl mp and become distoft-
ed. 1t also attacks the young, growing
stems and the flower buds, On the latter it
causes crnmpiing and frequently brown
dlscolorntion OF the outer petals, while 1t also
reduces the SIZE of the flower. The fungus
causing the trouble appears as a very thin
dusty white covering on. ;he surface Of the
parts attacked. The dusty appearance is
due to the production of myriads Of spores
that are ab.e to germinate on healthy plants,
and thus start the disease on them.
Some varieties OF roses are much more
susceptible to miidew than are others, but
this fact is of little use III preventing the
disease from appearing in West Indian gar
dens, partly because it is not easy to obtain
information as to what varieties are compare
lively immune and what are not but mainly
because the best roses are often the most
susceptible, aud unless immune varieties can
be found with almost identical flowers, the
more attractive forms will be planted wheth-
eli they are immune or not.
Various measures have been recommended
for the control Of the disease. One method
is to dust he plants with a mixture of ,
parts by volume of flowers of sulphur with
l part of quicklime. This mixture should
be put in Il muslin bag and shaken ON to the
plants III the same manner as that III which
cotton plants are busted with Paris green.
The treatment should be repeated about
every ten days, until the trees arc free
from mildew. The powder adheres Gest
when the leaves are Sill htly damp with
dew or from the effects of II light show
Ell. Another method of treatment is to
spray or wash the plants with u solution of
liver of sulphur, scientifically known rs pot
assium sulphide. This may be made 10y dis
solving / OF. Of liver of sulphur, obtained
from a chemist, in 3 gallons Qmperial) OF
water; this is equivalent to 3 3/5 wine gallons
such as are used in Barbados. 4 ltable
vessel to use is an old Kerosene tin that has
been thoroughly freed from oil by scrubblug
with hot water and sand. Another solution,
recommended by Massee, is that consisting
of l part of sulpEuric acid in 1900 parts Of
water. For practical purposes, there should
be obtained from the chemist Il solution
containing l part OF strong sulphuric "cld
and 8 parts of wateE. One ounce Of this
mixture should be added to an Imperial gal
lon Of water contained in a clean wooden tub
or in an earthenware dish.
Both the liver of sulphur and the sulphu-
rc acid solutions will scorch young leaves,
if the mixture is too strong; and the effect OF
their application should be carefully watched.
In addition to the two solutions already
described, various proprietary substances
are recommended for treating rose miIdew,
and some of them have been found to give
quite satisfactory results. Directions for
preparing these substances for use are as a
rule supplied with them.
The actual application of solutions of fun
gicides often presents some difficulty, N a
garden. The ordinary garden syringe, even
when it is provided with a fine lose nozz e,
does hot Usually give a spray that will adj
here well all over leaves with a thin, waXy
coating. Either the solution falls rs minute,
practically spherical drops on the leaves, or if
the plants are further wetted the liquid runs
into big drops, which evaporate slowly, leay-
ing a somewhat too concentrated solution on
the leaves in some places and none at all IN
others. The drops Of strong solution scorch
the leaves, and on he other parts the dis
ease is not affected. In either of the above
cases the spraying is Of very little use. A
method that would probably be found far
more satisfactory, and one that is quite prac-
ticable on a small scale, is to wipe carefully
each of the diseased parts with u soft sponge
dipped in disintecting solution. The leaves
not be made too wet all that is ne