August i, 1889.] THE TROPICAL AGRICULTURIST. 
99 
Prof. Biley is of opinion that this same treatment 
would prove beneficial as a check to leaf-disease 
as he has employed it successfully against an allied 
disease of the vine.— Yours very truly, 
E. EENEST GEEEN. 
From the works referred to, we quote as follows : — 
Soap and Kerosene Emulsions.— The difficulty of ob- 
taining fresh milk in Florida, and the cost of con- 
densed milk, have made a cheaper substitute desirable. 
This is found in a solution of soap, whioh forms with 
kerosene an equally good emulsion. The quantity of 
soap used in solution need not exceed one-quarter of a 
pound to one gallon of water, but stronger soap solu- 
tions are required to form a permanent emulsion. The 
percentage of kerosene may also be varied greatly. But 
emlusions containing over 80 per cent of the oil have 
too light a specifio gravity and are not readily held in 
suspension in water. On the other hand, in the pro- 
cess of emulsifioation, kerosene loses a portion of its 
value as an insecticide, and emulsions containing less 
than 30 per cent of the oil, although they do not at all, 
or only very slowly, rise to the surface when diluted 
with considerable quantities of water, are nevertheless 
too much weakened for effective use against Scale- 
insects. 
The following formula is considered the best for 
general use. It gives a wash of sufficient strength to 
kill the eggs of those species of Scale-insect which are 
now commonly found in Florida, although in dealing 
with some of the Aspidiotus scales a somewhat stronger 
emulsion may be required. 
Formula : — 
Kerosene 2 gallons =67 per cent. 
Common soap or whale-oil ] 
soap 5 pound > =33 per cent. 
Water 1 gallon ) 
Heat the solution of soap and add it boiling hot to 
the kerosene. Churn the mixture by means of a force- 
pump and spray-nuzzle lor five or ten minutes. The 
emulsion, if perfect, forms a cream, which thickens on 
cooling, and should adhere without oilinessto the sur- 
face of glass. Dilute before using, 1 part of the emul- 
sion with 9 parts of cold water. The above formula 
gives 3 gallons of emulsion and makes when diluted 30 
gallons of wash. 
Necessary precautions in the, use of Kerosene. — A 
reckless use of any penetrating oil upon plants can- 
not fail to prove detrimental. Kerosene is, however, 
muoh less injurious than the higher oils, naphtha, 
benzine, &c, with which, in a crude state, it is asso- 
ciated. The refined oil, such as is commonly used for 
illuminating purposes, is safer, and should always be 
used in preference to the lower grades, which contain 
a large admixture of other oils exceedingly deadly to 
vegetation. 
Effect of Kerosene upon the Orange. — Although the 
aotionof kerosene proves more in jurious to some plants 
thau to others, a healthy orange tree is but Blightly 
affected by it, and will even support without serious 
injury applications of the undiluted oil if judiciously 
made, i.e., applied in fine spray and avoiding exposure 
of the \i ant to hot sunshine or to frost before the oil 
has evaporated. Unhealthy trees and trees suffering 
from the attacks of Scale-insects receive a shock more 
or less severe, according aB their vitality is more or 
less impaired. Young, tender shoots, budding leaves 
and blossoms, are not much affected by kerosene, and 
may even be dipped in the pure oil with impunity. 
The heat of the sun increases to an injurious extent 
the action of kerosene, and applications of very strong 
solutions or undiluted kerosene, if used at all, should 
be made on cloudy days or at evenings. 
Milk or soap emulsions containing 60 or 70 per cent of 
oil and diluted with water teu times are more nearly 
harmless to the Orange than any other insecticide 
capable of killing the Scale-insect. Nevertheless the 
plant receives a shock, imperceptible when the tree is 
in good condition, but sulliciently severe when it is in- 
fested and injured by Scale to cause the loss of the old, 
devitaliz id leave*. Complete defoliation and the death 
of moribund twigs and branches may be expected to 
oocur in extreme cases. The shock is invariably fjl- 
lowed by a reaction, and in ten to fifteen days new 
growth appears. The growth is healthy and natu- 
ral, and if the application has been sufficiently 
thorough to destroy the Scale-insect, results in perma- 
nent benefit. 
Enough has been said to show that kerosene ia a 
powerful remedy, perfectly effective and safe if used 
in moderation, but hurtful in strong doses ; that its 
use undiluted is attended with danger, is entirely un- 
necessary, and cannot be recommended. In Appendix 
II will be found an examination of results obtained in 
experimental applications of kerosene, together with 
other insecticides, arranged in tabular form for conve- 
nience of comparison. 
The most favourable season for applying kerosene 
washes is undoubtedly early spring or as soon as all 
danger of frost is past. The Bheilding of the last year's 
leaves, whioh tabes place naturally after the orange 
tree has renewed its foliage iu spring, is often accele- 
rated by the action of the oil, which is thus made to 
appear very severe. But the loss of old and devita- 
lized leaves is one of slight consequence, and in the case 
of badly infested trees is a positive advantage, as the 
leaves in falling carry with them the scales most diffi- 
cult to reach with insecticides. 
THE APPLICATION OP INSECTICIDES. 
Fineness and Force of Spray. — In dealing with an enemy 
so thoroughly protected as are many of the Bark-lice, 
liquid insecticides should be applied in as fine a spray 
as possible, or at least in moderately fine spray, driven 
with considerable force, in order to inorease to the ut- 
most their penetrating power. The aim should also be 
to reach and thoroughly wet every portion of an in- 
fested tree, so that no individual Scale-insect shall es- 
cape the action of the liquid. This result is not at- 
tainable by the old method of sending a jet from a 
distance into the tops of the trees. An ordinary garden 
syringe is practically useless. There is needed a force- 
pump and a nozzle giving a finely atomized spray. Thi- 
nozzle should be attached to a sufficient length of flexs 
ible hose to allow it to be introduced into the top of 
the trees. The orifice of the nozzle should be directed 
at a right angle to the hose, and not in line with it. 
The jet of spray may thus by a turn of the wrist be 
directed upward or downward, and brought into con- 
tact with all parts of the foliage and branches, from be- 
neath as well as from the upper side. 
The Cyclone Nozzle. — A nozzle whioh answers the 
above conditions and is easily attached to any force- 
pump by means of a rubber tube is described in the re- 
port of the Entomologist. It consists of a shallow, cir- 
cular metal chamber soldered to a short piece of metal 
tubing as an inlet. The inlet passage penetrates the 
wall of the chamber tangentially, admitting the fluid 
eccentrically, and causing it to rotate rapidly in the 
chamber. The outlet consists of a very small hole 
drilled in the exact centre of one face of the chamber. 
The orifice should not be larger than will admit the 
shaft of an ordinary pin. Through this outlet 
the fluid is driven perpendicularly to the plane of 
rotation in the chamber. Its whirling motion dis- 
perses it broadly from the orifice, and produces a 
very fine spray, which may be converted into a cloud 
of mist by increasing pressure in the pump. The 
perforated face of the nozzle-chamber is removable 
for convenience in clearing the orifice when it clogs. 
The diameter of the chamber inside need not exceed 
oue-half inch and its depth one-quarter inch. A 
nozzle of these dimensions attached to the aquapult 
pump covers one and a half square yards of surface 
at a distance ok ; 4 or 5 feet from the orifice. The 
amount of dispersion depends somewhat upon the 
thickness of the perforated face of the chamber. 
The diameter "f the cone of spray may be increased 
by countersinking the exit hole and making its 
edges thin. 
Three-eighths-inch gum tubing is sufficiently large 
to supply one or a gang of several nozzles. The tubing 
must be strengthened with one ply of cloth. 
In use, the end of the hose is supported by being 
fastened to a light rod of wood, which forms a handle, 
by means of which the nozzle may be applied to 
all parts of the tree. For full-sized trees a rod 1< [ig 
