Evening star., 1940-03-30

kinds of pests or diseases. The bot
of applying at the appointed time !
convenient to omit them. The que
substitute? We certainly do not en-
and there is little pleasure in having
Perhaps combination spray or
will at least reduce labor requirement
somewhat less effective than the s.
apply them with less work and equi
are more apt to use them and hence S
control is far better than no control
The next step is to decide betwee
ties claim dusts to be as effective g
people who are supposed to know do
not agree, we will assume them to be
equally effective in controlling in
sects and diseases.
Dusts Are Easy
To Apply.
Sprays stick to the foliage better
than dusts but take little longer to
apply. With a spray there is less
discomfort from breathing the ma
terials than with dusting. On the
other hand, dusts may be prepared
In advance and can be put on in a
few minutes. A dust, however, may
be applied only when the air is STILL
whereas spray may be applied dur
ing light breeze. Sulphur dust will
burn the foliage when temperatures
are above 90 degrees. With these
points ir mind. take your choice.
Either one will work
Combination sprays may be
bought under various trade names.
In selecting one. however. the gar
dener should make certain that 1t
contains a fungicide bordeaux, sui
phur, etc., contact poison tnlco-
tine sulphate or pyrethrume for
sucking insects and stomach poi
son (arsenate. pyrethrum, etc. for
the chewing insects. Some OF the
combination sprays contain only Il
fungicide and a stomach poison, the
contact poison having to be added.
Pyrethrum is an effective poison for
both. the chewing and the sucking
insects and is non-poisonous to
warm -blooded animals.
Similarly, combination dust,
should contain each of these. II
it contains arsenate, then tobacco
dust should be added for the suck
ing insects.
Dusts to be effective should be
very finely pulverized 600 mesh) .
Where the home gardener mixes
his own dust he should add lime
to increase the separation OF the
sulphur (finely ground sulphur often
tends to stick or f1ow). Speaking OF
home mixtures. the one known as
Massey dust consists Of parts dust
Ing sulphur 2 parts each of hydrated
lime. lead arsenate and tobacco dust.
The measurements are by volume
This dust can be mixed in quanti-
ties ahead of time and stored In
dry place. (Note-Lead arsenate is
a deadly poison and should be placed
beyond the reach of children0
Best Time for
Spraying.
So much for the choice of mate
rails. When to apply is the next
problem and it is not an easy one
to decide. One good gardener told
me that he plans to make an apph-
cation each Sunday morning. Once
a week, however, may not be often
enough in the spring when the
leaves are making rapid growth and
when showers are frequent. In the
heat of summer, when growth is
slow and showers are infrequent.
once in two weeks may give ade-
uuate protection. Often enough to
keep the foliage fully covered-top
and bottom-should be the deter
mining factor. The poison for the
chewing insects should be there
when they take bite. Similarly,
when a disease spore reaches the
leaf fungicide should be present to
kill 1t. After insects have eaten the
leaves or disease spores have entered
the leaf tissues it is too late to spray.
The above sprays and dusts are,
Of course, at most seasons inef1ec-
tive In controlling scale insects. This
group of pests have various kinds
of protective coatings. They are
controlled with sprays, which because
of their strength can only be ap-
piled when the shrubs are dormant
Hence the common name for them
is dormant sprays" Dormant
sprays should be applied before the
leaves appear and on a day when
the temperature is above As and
not likely to drop to 80 for at least
IL hours.
Perhaps a further word Is needed
In explanation Of what is meant by
the chewing, sucking and scale In
sects. Chewing insects are those
that devour the foliage, such as
worms, aster beetles, etc. With the
exception of the Japanese beetle,
they are easily controlled by the
common stomach poisons-lead ar
senate, pyrethrum and the f1ourine
compounds. The Japanese beetle
may be partially controlled with lead
arsenate q ounces of lead arsenate
of the powdered acid type and IL
ounces of wheat flour to the gallon
of water).
Sucking insects, chiefly aphids
and thrips, must be hit by spray
to be killed. This is not difficult, since
they tend to cluster on the tender
tips of plants and shrubs. A strong
blast of water from the garden hose
will control red spiders. Sulphur
dust is also effective. Nicotine sui
phate. sold under various trade
names, is, however, the commonly
used control for sucking insects.
The scale insects, such as the
oyster shell scale, tulip scale. cot
tony cushion scale, anonymous
scale, etc, attack woody trees
and shrubs. The lilac. euony-
NOUS, tulip poplar and some of the
towering crabs are troubled by
these pests. A dormant spray each
spring is usually an effective con-