ROSE PESTS
THE enemies of the rose are many. They are of two classes; the insect
foes, and diseases caused by Fungi. And their prevention and destruction
are tasks, as every rose-grower knows only too well, which call for
ceaseless vigilance and constant work, more especially in the early
months of the season. For if remedies are applied in good time, the
pests of both kinds give comparatively little trouble after May and June
until the early autumn, when a fresh crop of both appears.
No such powerful weapon has ever before been put in the hand of the
rose-grower, as the remarkable handbook on the _Enemies of the Rose_,
published this spring (1908) by the National Rose Society. For here the
veriest tyro can recognize the diseases which puzzle him and the insects
which drive him to despair in all stages of their mischievous existence,
figured in exquisitely drawn and coloured plates; while in the terse and
admirable letter-press he is told how to combat their destructive ways.
This little book can be obtained by non-members of the Society for
2_s._ 6_d._, through any member; and it ought to find a place on the
shelf of every rose lover.
=Mildew=, of all Fungoid diseases, is the worst we have to contend with.
Some roses, such as the lovely _H. T. Killarney_, the _Crimson Rambler_,
the _H. P. Margaret Dickson_, and others, are specially subject to this
pest; and unless measures are taken against it when the very first sign
appears, it quickly spreads to other roses. Two seasons ago a plant of
_Margaret Dickson_ had it badly in my garden, and infected its
neighbour, _Frau Karl Druschki_, to an alarming extent.
This odious disease, though more or less always present in the garden,
appears generally in marked strength twice in the season--first in
spring, when the foliage is just fully developed, and secondly after the
midsummer shoots are grown.
It must be attacked early before it gets any hold, in fact, before it
actually shows, if we have reason to suspect its presence. _Flowers of
Sulphur_ is the most usual and effective preventive. It is blown over
the plants with bellows made specially for the purpose. Floating like a
fine cloud all over the garden it settles on every part of the plant.
The early morning before the dew is gone is the time to apply it, as the
evaporation of the dew has some subtle effect on the sulphur which
greatly increases its efficacy. Rev. F. Page-Roberts strongly
recommends _Black Sulphur_ instead of the ordinary yellow, used with one
of the "Ideal" Powder Bellows, made by W. Wood & Son, Wood Green.
Another preventive, which is advised in the National Rose Society's
handbook as extremely efficacious, is syringing with _Potassium
Sulphide_, _Liver of Sulphur_--half an ounce to a gallon of water. The
handbook advises adding a tablespoonful of liquid glue, or the whites of
two eggs to every gallon of water, as this causes the solution to adhere
better to the foliage. If thoroughly and carefully applied with a very
fine syringe, such as the Abol Syringe, using the bend attached to get
at the under-side of the leaves where the fungus first appears, this
wash acts rapidly upon the pests.
_Mo-Effic_, a new preparation, has been highly recommended in the last
two years. I have not tested it myself. But Mr. Mawley considers it most
successful.
=Black Spot= is another troublesome pest. It attacks the foliage alone,
and not only spoils the appearance of the leaves, but so injures them
that they fall off prematurely. The disease can be best checked by
spraying with the _Liver of Sulphur_ wash, beginning early in the spring
and going on at intervals.
=Rose Rust= and =Rose Leaf Scorch= may also be combated with _Liver of
Sulphur_ wash.
But in all these three last diseases, it is a matter of the greatest
importance to collect the badly diseased leaves on the plant, and
especially to pick up every one lying on the ground, and to see that
they are burnt at once and not thrown on the rubbish heap, where they
will only infect the soil.
=Sooty Mould=, the unsightly black stuff which often covers the foliage,
is a parasitic fungus not upon the leaf itself but upon the "honey dew"
deposited by Green Fly. If therefore the honey dew is kept off by
destroying the Aphides which secrete it, _Sooty Mould_ will not appear.
INSECT PESTS.
=Green Fly=, or =Rose Aphis=, is alas! too well known in every garden to
need much description. But the reason why it is so difficult sometimes
to get rid of this pest is not so commonly known. The Aphides breathe
through pores at the sides of their bodies. And in order to kill them,
some substance must be used which will close these pores. Therefore
syringing with water or any clear liquid is absolutely useless; for if a
few Green Fly are knocked off one shoot they will only settle on some
other. We often hear people say after a thunderstorm, "This will clean
the roses and wash off the Green Fly nicely." Far from it. They only
increase the faster; while the caterpillars rejoice, and flaunt
themselves openly on every bush. Then in despair some one uses paraffin
or some violently caustic wash for spraying the Green Fly, and destroys
his roses thereby.
Nature has mercifully provided some enemies to prey on the Green
Fly--and these help in some small degree to keep the pest down. The
chief of these is the Ladybird, which both in its adult and in its
larval state devours them ceaselessly. The pretty green Lace-wing Fly or
Aphis Lion is also useful, as its larvae are provided with "large
sickle-shaped jaws for picking the Green Fly off the plants."
The Hover Fly--which looks like a small, slim two-winged bee or
wasp--lays its eggs in the thick of a mass of Green Fly, and its green
and grey leech-like maggots feed upon them. And the Ichneumon and
Chalcid Flies lay their eggs in the bodies of the Aphides and their
maggots feed on them from within.
But all these are of comparatively little help to the unhappy rosarian,
who must therefore devise unnatural means to clear his plants.
As far as I know, with the exception of an Aphis brush--a useful
invention, but one which needs very gentle handling--there are only two
safe remedies for this universal plague. The usual one is a wash of
soft-soap and quassia, in these proportions--
Best soft-soap 1 lb.
Quassia chips 21/2 lb.
Water 25 gallons.
Even this wash, excellent as it is, will sometimes fail to get rid of
the scourge in a bad year. But I have found "Abol, White's Superior," a
never-failing remedy. It is also much easier to use, as one only has to
mix it with cold water according to the directions on each can, and it
is ready in a minute.
If either of these remedies are used the moment the Green Fly appears,
and the dose repeated a couple of days later in order to kill any that
may have escaped the first spraying, we have very little more trouble
until the second crop of Green Fly appears in September. It is well to
syringe the plants thoroughly with pure water a few days after the
second dose of either of these washes, as this knocks off the dead
Aphides, and leaves the foliage clean and sweet.
Although paraffin in various forms is often recommended, let me urge
upon my readers that it is a most dangerous substance to use upon the
rose--a naturally delicate plant--as any remedy of a caustic nature is
sure to do it far more harm than good.
Tobacco wash is recommended by the Continental rose-growers for Aphis, 1
part of tobacco-juice to 15 parts of water. If a little soft-soap is
added it makes a better wash. This is also a good wash for
=Cuckoo Spit= or =Frog-Fly=.--This frothy substance if washed off will
be found to contain a yellow creature, often closely wedged into the
angle of leaf and shoot, or at the base of a flower bud. This is a
"nymph" or young Frog-Fly--a most destructive insect--and unless removed
it will so quickly suck the sap of the leaf and bud that it dies and
falls off.
To get rid of them requires patience. We must either hand-pick the
roses--or if we spray with the tobacco wash it is necessary to syringe
the plant with plain water first, using some force, to wash off the
white froth--and then spray with the tobacco wash to kill the "nymph."
This leads us to the more active and the worst of all the pests we have
to fight against.
BEETLES, BEES, FLIES, AND MOTHS,
which either in their adult form or as maggots and caterpillars prey
upon the rose.
Four Beetles are among the enemies of the rose. The beautiful green
=Rose Beetle= or =Rose Chafer= does harm in both stages. As a grub it
feeds underground on the roots; and as a beetle eats the foliage and the
petals and anthers of the flowers. I find it is particularly fond of the
delicate blossoms of the _Yellow Persian Briar_.
The =Cock Chafer= also eats the foliage, and its large white grubs
devour the roots of the roses to such an extent that they often kill the
plant. As the grubs remain for three years in the ground the damage they
can do is incalculable; and they attack other plants besides roses.
Among the roots of a herbaceous Spiraea I lifted this last winter, I
caught forty of these grubs, and found they had so honey-combed the
roots that the plant had to be burnt.
The =Summer Chafer= and =Garden Chafer= also attack roses.
Where these four chafers are prevalent there is no cure but
hand-picking. The beetles must be collected off the bushes; and the
grubs carefully picked out of the roots, if we have reason to think they
are present from the rose appearing unhealthy. Or they may be tempted
out of the soil by placing grass turves upside down close to the plants,
when they can be picked out and killed with a little boiling water.
The =Rose Leaf-cutting Bee= spoils the foliage by cutting semi-circular
pieces out of the leaves to line its nest. A few years ago I found that
a fine young plant of _Tea Rambler_ was so relished by this bee that
hardly a leaf was left intact. There is no cure but to watch the bee
going into her nest and there to destroy it after dusk.
* * * * *
Of all pests that the rose-grower has to fight against
CATERPILLARS AND MAGGOTS
are the very worst. For there is no real remedy against their endless
and varied depredations save hand-picking; or as some one has tersely
put it, "just a little gentle washing with non-caustic substances, and
just a lot of finger-and-thumb work." This is tedious, and often
disgusting; but it is the only way.
These loathsome pests are the larvae of certain flies and many kinds of
moths.
=Sawflies=, the little black and shiny flies which infest the roses in
May and June, are a terrible pest, as the eggs they lay on the leaves
turn quickly into small, green larvae. There are several kinds of
sawflies, and their destructive methods vary. The Leaf-rolling Sawfly,
whose larvae roll the rose-leaves like paper spills, has become a serious
pest among garden roses of late years, and if these rolls are carefully
unfolded the little green maggot will be found in one of them. It must
be caught with care, as it is very lively, and if allowed to fall to the
ground will remain there, and produce a fresh brood in the next year.
The =Rose Slugworm= is much more common, and most destructive, eating
the upper surface of the leaves and leaving the lower to shrivel up. It
has two broods in the year.
The =Rose Emphytus= is another of the sawflies, and one of the worst.
Its larva eats the whole leaf away, beginning at the mid rib, and also
works its way into a cell in the branches till the next spring, thus
killing the tender growths above. This is the green caterpillar which we
find coiled up on the under-side of the rose-leaves, or in early morning
and late evening curled round the base of a rose-bud, working its way
through the calyx into the heart of the flower. It is far easier to
catch, as it is somewhat sluggish in movement, clean and hard in
substance--and therefore less disgusting to touch than others that
squash in one's fingers. The best remedies for these pests are: first,
prevention, by spraying with hellebore wash, which I have found most
useful. Second, by careful hand-picking when the larvae appear. And
third, by removing the surface soil in which the cocoons are buried, and
all dead wood, during the winter.
Hellebore wash is made in the following proportion--
1 oz. fresh-ground hellebore powder.
2 oz. flour.
3 gallons of water.
Mix the hellebore and flour with a little water till dissolved; then
stir into the rest of the water and apply with a fine Abol Syringe.
=Caterpillars= of many moths are among the most deadly foes of the rose.
Some eat the foliage--such as the Buff Tip and Vapourer Moths; others
tunnel into the leaves. But the worst of all are the Tortrix Moths or
Rose Maggots, whose repulsive grubs eat the unopened blossoms and spin
the delicate young leaves together, destroying the whole top of the new
shoots. There are many varieties of Tortrix, which are all quite small
moths, and their caterpillars or "Maggots" are the most unpleasant and
destructive of all we have to deal with. The worst of all are the Red
and the Brown Rose Maggots. These creatures are dirty red or brown, with
black heads; they are soft, and grow very fat, and when full grown are
half an inch long. They spin the leaves together at the top of the
tender young flowering shoots, often bending the top down; and not only
eat the leaves in the midst of this filthy fortress, but eat their way
into the buds and destroy them.
Other Tortrix Moths have green and yellow-green maggots. The worst is
the Green Rose Maggot--bluish-green with a black head. It also spins the
leaves together, and grows nearly as large as the brown. It is extremely
active, and very soft and slimy.
These all turn to pupae among the leaves instead of in the soil; and any
left in the foliage must be picked out and burnt. If we wait until the
shoots and buds are eaten and the foliage spoilt--nay, till often the
whole of our early flowers are ruined--the only remedy is to pinch the
leaves which conceal the maggot, if we have courage to do so, or to
hand-pick every one we see. But happily a way exists of preventing these
loathsome pests from destroying our roses. And this is to spray the
plants from the middle of April to early in May with _arsenate of
lead_.[9] This should be done twice, and will prevent many other
caterpillars from feeding on the foliage.
=The Vapourer Moth=, the little golden brown moth with a tiny white
crescent on each wing, is unfortunately common everywhere, in town as
well as country; and its caterpillars are as destructive as they are
beautiful. These caterpillars are found in great masses upon the
hawthorn and fruit trees, and attack the rose as well. They are
handsome, hairy creatures, spotted thickly with bright pink-red
tubercles, with four erect tufts of yellow hairs on the back, and five
longer tufts of darker hairs, two pointing forwards, one backwards over
the tail, and two at the sides.
If there are too many to be hand-picked the bushes must be sprayed with
_arsenate of lead_.
=The Buff Tip Moth= does most harm in the autumn, when its caterpillars,
yellow and green, with longitudinal black lines divided by yellow bands,
appear in colonies, feeding upon the surface of the leaves. They should
be picked off at once, before they grow large, as they reach a length of
two inches when full grown, and disperse, feeding singly. If very
plentiful, spraying with _arsenate of lead_ will destroy them.
=The Winter Moth=, which is such a serious pest among fruit trees, also
attacks roses. The caterpillar is hatched very early, in the end of
March and beginning of April. It is a "Looper," greyish at first and
turning green later, and nearly an inch long when full grown.
The grease bands we use on fruit trees to catch the wingless female as
she creeps up in the autumn to lay her eggs on the bark, would be
difficult to use for rose-bushes. The only plan therefore is to spray
very early in the season with _arsenate of lead_ wash.[10]
Another "Looper" found early on the roses is that of the =Mottled Umber
Moth=. It is brown with yellowish sides, looks almost like a twig, and
is over an inch long. It must be hand-picked.
The =Dagger Moth's= caterpillar--a long, grey-black creature with a
yellow line along the back, a large black hump on the shoulder and a
small one at the tail, is most destructive when it appears in late
summer and early autumn. It is generally found singly; but one specimen
will strip a whole shoot of leaves, leaving only the mid rib.
Hand-picking is the only remedy.
These are the chief of the pests which we have to fight against. And if
we desire to keep our roses in health and beauty we must remember that
prevention is better than cure, and begin our treatment in good time,
before the many enemies of the rose get too firm a hold.
REMEDIES FOR ROSE PESTS
WASHES, ETC.
For Aphis or Green Fly.
1. _Abol._ _White's Superior_-instructions with
each can.
2. _Soft soap and Quassia Wash._
Best soft soap 1 lb.
Quassia chips 21/2 lb.
Water 25 gallons.
Dissolve the soap in boiling (soft) water. Boil the chips or simmer for
twelve hours, adding water from time to time to cover them. Strain off
the liquid, mix it with the dissolved soap, stirring them together
thoroughly, then add the water.
3. _Tobacco Wash_--also useful for Cuckoo Spit,
Thrips and Leaf-Hoppers.
1 part tobacco juice.
15 parts water.
Add a little dissolved soft soap.
4. _Hellebore Wash_ for Sawflies.
Fresh-ground hellebore 1 oz.
Flour 2 oz.
Water 3 gallons.
Mix the flour and hellebore powder with a little water. Then add the
rest of the water. It must be kept stirred, and used with a fine spray.
_Hellebore is poison._
5. _Arsenate of Lead_ for Caterpillars.
This is a poisonous wash, but the only one that can be used without
hurting the roses. It is made with the paste known as _Swift's Arsenate
Paste_, mixed with water.
6. _Flowers of Sulphur_ blown over the plants for
Mildew.
_Liver of Sulphur Wash_ for Mildew and other fungi, and for Red Spider.
Liver of sulphur 1 oz.
Water 10 gallons.
Powdered hellebore may be dusted over the bushes for Sawflies, but the
hellebore wash is best.
All these washes can be used with the Abol Syringe. And in large gardens
Vermorel's Knapsack Sprayer is almost indispensable, as it does equally
well for roses and fruit trees.
FOOTNOTES:
[9] p. 149.
[10] p. 149.