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JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
[ November 17, 1892. 
THE THEORY AND PRACTICE OF SPRAYING. 
Insects and fungi are the principal agents which reduce the 
value of crops, but since the grower has, at his command, means 
of destroying these pests, he has, as a rule, no one but himself to 
blame if he is much troubled by them. By spraying plants with 
suitable materials, a good crop can almost be guaranteed, provided 
that the conditions for the healthy development of the plants are 
present. Spraying in itself will not produce good crops, but it will 
prevent injurious agencies from affecting the crop which would 
naturally be produced. It is an operation which is designed to 
protect plants, not to make them grow more vigorously or to bear 
more profusely, although these results are, nevertheless, indirectly 
obtained. An injured plant will not do so well as a sound one ; a 
Vine covered with mildew cannot be so vigorous as one not so 
affected. Countless instances could be brought forward to show 
how plants have lost all their foliage through the action of insects. 
Bat whether the foliage is ruined by insects or by fungi, the effect 
upon the plant is the same, checked growth and a loss of vigour. 
Thousands of pounds are annually lost on account of the injury 
done by fungi and insects. Almost every cultivated plant has 
its enemies, but almost every one of these can be overcome by 
persevering and intelligent application of remedies within easy 
reach. 
The substances used in spraying may, in general, be divided 
into two classes, insecticides and fungicides, the former being used 
against insects, the latter against fungi. Insecticides may further 
be divided into two classes, according to their mode of action ; 
those which act after entering the body of the insect, with its food, 
and those which kill by coming into contact with the external 
surfaces of the insect’s body. 
This division of insecticides is an important one. Take for 
instance the Potato beetle. This insect is a voracious feeder, and 
by placing some poisonous substance upon the foliage which is 
eaten by it, the poison enters the body with the food, and the 
beetle soon stops work. Currant worms, caterpillars, curculios, 
in fact all insects which feed upon the external tissues of plants 
may, with but one or two exceptions, be destroyed in this way. It 
is the easiest and cheapest method, and should be employed as far 
as possible. The insecticides which are commonly used are Paris 
green, London purple, white arsenic, and hellebore. Paris green 
is the safest, but the most expensive of the arsenites. Its arsenic 
is mostly in an insoluble form, hence it does not injure foliage so 
much as the others. It is generally used upon all plants at the 
rate of 1 lb. in 200 or 300 gallons of water. Peaches are very 
easily injured by arsenites, and Paris green is the only safe one to 
apply, but even this should never be used stronger than 1 lb. to 
300 gallons water, and still weaker solutions give good results. 
The spray should be very fine, and the foliage should be covered as 
evenly as possible. London purple contains a large amount of 
soluble arsenic, and for this reason should never be applied to 
Peach trees. I have also seen Plums seriously injured by its use. 
It is generally applied at the same rate as Paris green, but the 
foliage is more apt to be scorched. The soluble arsenic may be 
rendered insoluble by adding a gallon of the milk of lime to every 
15 gallons of the London purple solution. When thus prepared 
London purple may be used with perhaps as much safety as Paris 
green. 
White arsenic is a dangerous substance, as it is so readily 
mistaken for other white powders. When used alone it is caustic 
to foliage, but the following treatment, recommended by the 
North Carolina Experiment Station, is said to make its use 
perfectly safe. Boil 1 lb. of commercial white arsenic and 2 lbs. 
of unslaked lime in 2 to 5 gallons of water for about half an hour. 
Dilute in 100 or 200 gallons of water before using. Hellebore 
is a vegetable product, and should be used upon plants which 
require spraying before the fruit comes to maturity. 
Insecticides which kill by contact are used against insects that 
suck the juices of plants. It is of no avail to try to destroy these 
pests by placing upon the surface of attacked plants those poisons 
which are effective only when eaten, as the beak of the insect 
passes through the external tissues of the plant before any food 
is taken. These insecticides, as a rule, are more difficult to 
prepare and apply than are those of the first class, but their use 
is often a necessity. Sucking insects generally have soft and 
tender bodies, readily penetrated by poisonous substances, such 
as kerosene and others which are fatal to the insect. In spraying 
these insecticides upon the plants, the aim should be to strike the 
insect, and not to cover the foliage with a coat of poison. If the 
insect escapes untouched, it will continue in its work as before. 
It is often hard to reach the enemy on account of the foliage, 
birk, or other protective substances ; but the excellent insecticides 
which we now have at our command in most cases insure the 
destruction of the pest, especially if a good nozzle and pump are 
used in making the application. However, before any insecticides 
are prepared it is necessary to determine in what manner the 
insects whose destruction is desired obtain their food. I once saw 
a man applying London purple to his Pear trees to destroy a 
sucking insect. Time, money, patience, and faith are all thrown 
away in such an operation. 
Kerosene emulsion is a good insecticide of this class. There 
are several formulas according to which it may be prepared. The 
following will give satisfaction :—Softsoap, 1 quart; kerosene, 
1 pint ; hot water, 2 quarts. Churn the materials by pumping 
back into the pail until well mixed. This should be diluted two 
or three times before being used. — E. G. Lodeman (in “ American 
Agriculturist”). 
IRIS IBERICA AND I. SUSIANA. 
These —two of the most singular and beautiful species of a 
large and most interesting genus of hardy plants—are not very 
frequently seen in gardens. This may arise from the prevalent 
but erroneous impression that they are amongst the most difficult 
of plants to flower, and require special treatment. As a matter of 
fact, they are easily cultivated, perfectly hardy, and not at all 
exacting in their requirements. I. iberica is a handsome plant, 
though its leaves are few. They are produced in a basal tuft, 
falcate, linear, and glaucous, and the stem does not exceed 6 inches 
in height, yet the flower is very large, often being 6 or 7 inches in 
length and 4 inches in breadth. The species flowers in spring or 
early summer. There are several forms, some being dwarfer than 
others, and these, as a rule, produce the most striking and the 
handsomest flowers. The blooms are solitary, the limb about 
3 inches deep, with the segments narrowing to a short claw, 1^ to 
2 inches broad ; the drooping petals or falls reflex from near the 
base, and are veined with dark purple or purplish-brown on a 
yellowish ground, with a velvety attractive dark purple blotch in 
the centre ; while the upright petals or standards are satiny white 
or pale lilac, veinless, yet pencilled and spotted with violet. There 
is a variety with white and another with yellowish falls, both 
veined with purple-black lines, and spotted and blotched with bay, 
the standards being veined and thickly spotted. In procuring 
rhizomes of this species it is almost certain that there will be 
several varieties and decided improvements on the common form, 
for this plant exhibits no departure from the well-known fact that 
cultivation improves the types. 
I. Susiana (the Mourning Iris) is described by Linnasus as “ the 
single-flowered bearded Iris, with the stalks longer than the leaves.” 
The limb is 3 inches deep ; the falls and standards are similar in 
shape and size, with dense fine lines and spots of brownish-black 
on a grey ground tinged with lilac ; the falls reflex about half way 
up ; the claw is cushioned with brownish-black hairs, whilst the 
standards are erect and much spotted. The flower is one of the 
largest of the Iris family, and when closely examined one of the 
most elegant, being composed, like those of the other Irises, of six 
petals, amongst which appear the three leafy heads of the style, so 
much resembling three others that the flower has been usually 
understood to be nine-petalled. It has no scent, but its beautiful 
colouring is enough to suggest a resemblance at a distance to the 
feathers of some Indian bird. The flowers are produced in late 
April or early May. The stalk is from a foot to 18 inches high, 
round, thick, jointed, and pale green ; the leaves rise six or eight 
together, and surround one another at the base. The root is 
tuberous, thick, irregular, and succulent. It is a native of the East 
(A.sia Minor and Persia), whence it was brought into Europe by 
the Dutch in the year 1573. 
These charming plants are best grown in a sunny situation 
sheltered from north, west, and east winds, but open to the south. 
The site should, in fact, be light and warm, and the soil thoroughly 
drained. The best bed I have seen was formed in a sunny nook, 
having low shrubs at a little distance on the east, north, and west 
sides. The soil was taken out 2 feet deep, as it was a mere gravelly 
brash, with 6 feet of ferruginous gravel below, resting on chalk, 
and the water never rose within that distance ot the surface. A 
foot in depth of black earth was taken from the rubbish heap, 
which contained every kind of stuff from the potting bench, and 
was of a rather strongish nature, yet friable from the large per¬ 
centage of crocks, and was put on the gravel, then another good 
foot was made up of soil consisting of dark rich turfy loam and 
leaf soil in equal parts taken from a wood, and a coating of sharp 
sand 4 inches thick was mixed with the surface soil to a depth of 
about 10 inches. The centre of the bed was occupied with the 
Susian Iris about 18 inches apart, and it was margined about 
9 inches from the edge with the Iberian Iris. 
The roots of the Iris Susiana were planted about 4 inches deep, 
being placed on about 2 inches depth of coarse sand and about that 
